Drug delivery system and method for controlled and continuous delivery of drugs into the brain by bypassing the blood brain barrier

CROSS-REFERENCE TO RELATED APPLICATIONS:

0001This application claims priority from <b>the</b><patcit id="pcit0001" dnum="US15177347A"><text>United States Non-Provisional Utility Patent Application No: 15177347 filed in United States on June 9, 2016</text></patcit><b>, the Indian Complete Patent Application No:</b><patcit id="pcit0002" dnum="IN201641014398"><text>201641014398 filed in India on April 26, 2016</text></patcit><b>and the Indian Complete Patent Application No: 3904/CHE/2015 filed in India on July 30, 2015.</b>

0002Application No: 3904/CHE/2015 filed in India on July 30, 2015 is a patent of addition to the Indian Complete Patent Application No: 1430/CHE/2014 filed in India on March 19, 2014.

FIELD OF THE INVENTION:

0003The present invention relates to a system for controlled and continuous delivery of drugs into the brain by bypassing the blood brain barrier, without the need for any surgical manipulation of the brain. The drug is delivered using an implantable device either beneath or above the respiratory mucosa, by surgically creating a window on the bone overlying the respiratory mucosa and accessing the connective tissue side of the respiratory mucosal lining from the oral or maxillofacial region. The locally delivered drug is transported through the neural, vascular or lymphatic routes or a combination of these routes and delivered into the brain by bypassing the blood brain barrier in human or animal patients. Accordingly, the present invention relates to the fields of drug delivery and medicine especially Oral and Maxillofacial Surgery, Neuroanatomy and Neurology.

BACKGROUND OF THE INVENTION:

0004The present invention relates to implantable devices, systems and methods for controlled and continuous delivery of drugs into the brain by bypassing the blood brain barrier, without the need for any surgical manipulation of the brain

0005The brain has good blood supply. As the brain is a highly sensitive organ, the cells lining the blood vessels in the brain are tightly arranged without any spaces between them to form a natural barrier called as the blood brain barrier. This blood brain barrier prevents entry of any foreign substance into the brain and thereby protects the brain. At the same time, it also prevents drugs present in the circulating blood from entering into the brain. Hence it is not practically possible to treat many medical conditions of the brain, even though the cause of the disease and the drug required for the treatment are known, because of the simple reason that the drug cannot enter the brain.

0006In the recent years, more information about the central nervous system and blood brain barrier have been unraveled using advanced molecular and imaging techniques. This has led to identification of newer therapeutic targets for drugs at the molecular level. New drugs have also been developed which can act on these molecular targets. Though in vitro studies and pre-clinical studies are positive for these drugs, they show high failure rate when administered in humans. This is mainly because the drugs are not able to enter the brain in the required therapeutic concentration to produce the pharmacologic effects. In fact, 98% of small drugs and almost 100% of large drugs are not able to cross the barrier. Hence there is a need for an effective drug delivery route which can deliver the drug into the brain at the right concentration in a continuous but controlled manner.

0007The methods available today for delivering drugs directly into the brain are mostly invasive. The methods include placement of micro-catheters or implants into the brain or use of various techniques to open the blood brain barrier. These techniques however make the brain also prone to infection as the brain gets exposed to the external environment. Advancement in the field of proteomics and genomics has led to discovery of therapeutic targets at the level of molecules or genes in the brain, leading to development of newer drugs. But these drugs also get destroyed when given orally. Hence alternative routes for drug delivery are the need of the hour.

0008<patcit id="pcit0003" dnum="WO2011098768A1"><text>WO2011/098768 A1</text></patcit> discloses an implantable fluid router and a catheter device that is implanted into the brain tissue for localized drug delivery. This neurosurgical procedure involves direct surgical intervention in the brain. <patcit id="pcit0004" dnum="US2002183683A1"><text>US 2002/183683 A1</text></patcit> discloses methods and devices that utilize iontophoresis for delivering biologically active agents into the central nervous system from the olfactory region, ocular region, brain surface and spinal cord. It comprises multiple components, is technique sensitive and invasive.<patcit id="pcit0005" dnum="US2007255237A1"><text>US2007/255237 A1</text></patcit> discloses an implantable drug delivery system for delivering drugs into the human inner ear. Drug is delivered locally into the deeper structures of the ear using the device. <patcit id="pcit0006" dnum="US2006084034A1"><text>US2006/084034 A1</text></patcit> discloses a method and device to raise the sub antral membrane floor of the maxillary sinus from the tooth bearing area of the oral cavity, in order to increase the height of the bone for replacing missing teeth with dental implants. <patcit id="pcit0007" dnum="US20141147809A"><text>US20141147809</text></patcit> discloses a dental implant which can aid in elevating the subantral membrane floor of the maxillary sinus while being implanted in the bone to restore a missing tooth.

0009Recent studies have shown that the nasal route can be used as a non-invasive route to deliver the drugs directly to the brain. But this route has limitations because controlled and continuous delivery of drugs at predetermined rates has not yet been achieved. The drugs also have to withstand mucociliary clearance, local enzymatic degradation and cross the epithelial layer before they reach the underlying connective tissue for further absorption. Hence only a smaller quantity of the total drug that is delivered, is finally absorbed. <patcit id="pcit0008" dnum="US2011151393A1"><text>US 2011/151393 A1</text></patcit> discloses a method of filling the maxillary sinus with drugs through the nose using a catheter and vision access <patcit id="pcit0009" dnum="WO0033814A2"><text>WO 00/33814 A2</text></patcit> discloses a method of delivering agents into the central nervous system by topical application of the agents on the external surface of tissues innervated by the trigeminal nerve that is outside the nasal cavity. But drug delivery is limited by the local factors like presence of epithelial barrier, local degradation and clearance. Drugs modified for endogenous transport mediated delivery across the blood brain barrier, using the naturally occurring molecular transport mechanisms at the endothelial cell have been developed for a few medical conditions. Yet the concentration of the drug delivered across the blood brain barrier using this technique is not predictable. Protein mediated drug delivery and viral mediated gene therapy ean induce immune mediated complications. Systemic routes like intra venous or intra-arterial need high concentration of the drug. Moreover, intra-arterial route results in severe complications. Therefore, an effective alternative route which can deliver drugs into the brain in a controlled and continuous manner, for a long period of time, without any complications or discomfort to the patient holds immense potential.

0010Trigeminal nerve supplies the nasal respiratory mucosa and the maxillary sinuses and relays at the nuclei in the brainstem. Cerebrospinal fluid has also been found to drain through nasal lymphatics. The nasal lymphatic channels are free of valves and can hence be used for drug delivery. Blood vessels in the nasal and maxillary sinus region transfer the drugs to the brain. The veins from the maxillary sinus and the nasal region drain into the pterygoid venous plexus which is further connected to the cavernous sinus. Therefore, the drugs delivered locally in these regions can drain into the pterygoid venous plexus and be further transferred into the cavernous sinus. The drugs can then enter the cerebral circulation at higher concentration without causing systemic toxicity either through the counter current mechanism at the cavernous sinus or through the perivascular pathways. Hence the drug delivered locally beneath the respiratory mucosa, is transported from the nasal and maxillary sinus region through the neural, lymphatic and the vascular routes into the brain by bypassing the blood brain barrier.

0011The air circulation in the maxillary sinus is unique. The maxillary sinus fills with air during expiration and is emptied of air during inspiration. Hence a drug delivered into the maxillary sinus by perforating the sinus lining mucosa from the connective tissue side can be easily inhaled when the air inside the maxillary sinus is emptied during inspiration. The drug can further come in contact with the nasal respiratory and olfactory mucosa for absorption. Also, the mucus on the maxillary sinus lining mucosa is moved towards the ostium opening and into the middle meatus of nose because of the muco-ciliary action. Hence the drug delivered on the maxillary sinus lining mucosa can also be transported by the muco-ciliary action through the ostial opening into the middle meatus and onto the nasal respiratory mucosa. Because of the increased retention time of the drug on the mucosal surface, higher quantity of the drug can be inhaled and be deposited on the nasal respiratory and olfactory mucosa for further absorption into the underlying connective tissue.

0012Goblet cells in the maxillary sinus lining mucosa secrete mucus. Drugs can be engineered for uptake from the connective tissue into the goblet cells, for further secretion along with mucus by the goblet cells. This can result in mucus loaded with high concentration of drug molecule for inhalation. The inhaled drug can be deposited on the nasal respiratory mucosa and olfactory mucosa for further absorption.

0013It therefore would be desirable to deliver drugs into the brain using a device without any need for surgical manipulation of the brain. It would further be desirable to provide a device which can be surgically implanted with its delivery tip located beneath or above the respiratory mucosa, by surgically creating a window on the bone overlying the respiratory mucosa and accessing the connective tissue side of the respiratory mucosal lining from the oral or maxillofacial region. It would also be desirable to deliver the drug in a controlled and continuous manner by connecting the device to an external drug infusion pump. The drug from the respiratory mucosa can be transported through the neural, vascular, lymphatic, inhalation or a combination of all these routes and delivered into the brain by bypassing the blood brain barrier and without causing any systemic toxicity.

SUMMARY OF THE INVENTION

0014The present invention provides a drug delivery system for delivering drugs into the brain, by bypassing the blood brain barrier. The drug delivery system comprises an implantable hollow device made of titanium or any other biocompatible material, that is placed into the bone overlying the respiratory mucosa of the maxillary sinus and the nasal cavity and a drug delivery tubing made of a biocompatible material that transfers therapeutic agents from an external drug reservoir into the central lumen of the implantable hollow device. An external drug infusion pump is used for providing continuous and controlled drug delivery of therapeutic agents from the external drug reservoir into the central lumen of the implantable hollow device.

0015A method of drug delivery into the brain by bypassing the blood brain barrier using the drug delivery system is described. The device is used to deposit the drug beneath the respiratory mucosa, by surgically creating a bone window on the overlying bone and accessing the connective tissue side of the respiratory mucosal lining from the oral or maxillofacial region. The drug delivered locally beneath the respiratory mucosa, is transported from the nasal and maxillary sinus region through the neural, lymphatic and the vascular routes into the brain by bypassing the blood brain barrier.

0016Another method of drug delivery into the brain by bypassing the blood brain barrier is described wherein the tip of the drug delivery device is placed into the maxillary sinus and above the level of the epithelial lining of the respiratory mucosa, by surgically creating a bone window on the underlying bone and perforating the overlying respiratory mucosa from the connective tissue side. The mucosa is perforated by removing the circumscribed bone with the trephine drill along with the underlying respiratory mucosa attached to the bone. The drug delivered into the maxillary sinus can be easily inhaled during inspiration and can be deposited at the nasal respiratory and olfactory mucosa for further absorption. The drug can also be transported through the ostial opening into the middle meatus and onto the nasal respiratory mucosa by muco-ciliary action. This results in increased retention time of the drug on the mucosal surface and so higher quantity of the drug can be absorbed into the connective tissue vasculature at the respiratory mucosa and the olfactory mucosa.

0017Drug molecules that are engineered for uptake into the goblet cells of the maxillary sinus lining epithelium, from the underlying connective tissue for further secretion by the goblet cells along with mucus are described. This can result in mucus loaded with high concentration of drug molecule for inhalation, which can be deposited on the nasal respiratory mucosa and the olfactory mucosa for further absorption. Drug molecules that are engineered for affinity to specific sites of the brain are described. This provides the required concentration of the drug in the targeted anatomical site in the brain.

0018The present invention is illustrated by the accompanying drawings of various embodiments and the detailed description given below. The drawings are not to scale. The detailed description and drawings merely depict exemplary embodiments of the present invention, for explanation and understanding and therefore should not be taken to limit the scope of the invention to the specific embodiments. Accordingly, the scope of the invention is to be defined solely by the appended claims and equivalents thereof. It will be appreciated that the components of the present invention illustrated in the drawings could be arranged, sized and designed in a number of different configurations.

0019Implantable devices and methods for controlled and continuous drug delivery into the brain by bypassing the blood brain barrier for a number of medical conditions including Parkinson's, Alzheimer, Pain Management, Epilepsy and Drug Addiction are provided.

BRIEF DESCRIPTION OF THE DRAWINGS:

0020<ul id="ul0001" list-style="none"><li><figref idref="f0001"><b>Fig.1</b></figref> shows the isometric side view (A), longitudinal sectional view (B) and three-dimensional view (C) of the single unit device.</li><li><figref idref="f0002"><b>Fig.2</b></figref> shows the isometric side view (A), longitudinal sectional view (B), and three-dimensional view (C, D), of a multi-unit device comprising a device with a central tubular inlet with external threads (205), a drug delivery assembly (206) and a retention cap (209).</li><li><figref idref="f0003"><b>Fig.3</b></figref> shows the isometric side view (A), longitudinal sectional view (B) and three-dimensional view (C, D) of a multiunit device comprising a device with a completely open second end (312) with smooth and rounded margin (301).</li><li><figref idref="f0004"><b>Fig.4</b></figref> shows the isometric side view (A) and three-dimensional view (B) of a multiunit device comprising a device with a central tubular inlet with internal threads (405) at the cervical third and a drug delivery assembly (406) with external threads (414) at its cervical part.</li><li><figref idref="f0005"><b>Fig.5</b></figref> shows the placement and removal tools (501, 503, 505, 507,509,511) for use with the device.</li><li><figref idref="f0006"><b>Fig.6</b></figref> shows the device in the form of a dental implant <b>(619)</b> with an internal spline <b>(618)</b> in the internal wall of body of the implant.</li><li><figref idref="f0007"><b>Fig.7</b></figref> shows an abutment in the form of a drug infusion source comprising a miniaturized internal drug infusion pump <b>(710)</b> and an internal drug reservoir <b>(709)</b> that is placed into the device in the form of a dental implant.</li><li><figref idref="f0008"><b>Fig.8</b></figref> shows the surgical placement of the device in the form of a dental implant <b>(805)</b> in the maxillary alveolar ridge <b>(803),</b> along with the placement and removal tools <b>(806, 811, 815).</b></li><li><figref idref="f0009"><b>Fig.9</b></figref> shows a mini plate <b>(A, B, C)</b> with a central reservoir dial <b>(902)</b> comprising internal threads and a porous apical wall <b>(903)</b> which is closed with a cap <b>(D)</b> with external threads <b>(907).</b></li><li><figref idref="f0010"><b>Fig.10</b></figref> shows a mini plate <b>(A, B, C, D)</b> with a reservoir dial comprising an angulated upper body (1002) for ease of access.</li><li><figref idref="f0011"><b>Fig 11</b></figref> shows the device with the porous apical wall <b>(1102)</b> located beneath the respiratory mucosa (1101).</li><li><figref idref="f0012"><b>Fig 12</b></figref> shows the device with the porous apical wall <b>(1202)</b> located above the level of the respiratory mucosa <b>(1201).</b></li><li><figref idref="f0013"><b>Fig 13</b></figref> shows the device <b>(1302)</b> placed on the anterior wall of the maxillary sinus with the drug delivery tubing <b>(1303)</b> extending into the buccal sulcus. The drug delivery tubing is connected to a drug infusion source comprising an external drug infusion pump <b>(1305)</b> and an external drug reservoir for continuous and controlled drug delivery.</li><li><figref idref="f0014"><b>Fig 14</b></figref> shows the device in the form of a prosthetic crown <b>(1410)</b> that is secured to a root canal treated tooth <b>(1408)</b> whose apex <b>(1402)</b> is in contact with the respiratory mucosa <b>(1401).</b></li><li><figref idref="f0015"><b>Fig 15</b></figref> shows the brain values of dopamine in a rabbit obtained using High performance Liquid Chromatography, after in vivo drug delivery of dopamine from beneath the respiratory mucosa.</li><li><figref idref="f0016"><b>Fig 16</b></figref> shows the blood values of dopamine in a rabbit obtained using High performance Liquid Chromatography, after in vivo drug delivery of dopamine from beneath the respiratory mucosa.</li><li><figref idref="f0017"><b>Fig 17</b></figref> shows the brain values of lignocaine in a rabbit obtained using High performance Liquid Chromatography, after in vivo drug delivery of lignocaine into the maxillary sinus and on the epithelial surface of maxillary sinus mucosa by perforating the lining mucosa from the connective tissue side.</li><li><figref idref="f0018"><b>Fig 18</b></figref> shows the blood values of lignocaine in a rabbit obtained using High performance Liquid Chromatography, after in vivo drug delivery of lignocaine into the maxillary sinus and on the epithelial surface of maxillary sinus mucosa by perforating the lining mucosa from the connective tissue side.</li></ul>

DETAILED DESCRIPTION OF THE INVENTION

0021The following detailed description of exemplary embodiments of the invention makes reference to the accompanying drawings which form a part hereof. The exemplary embodiments of the invention and the method to practice the invention are hereby illustrated in the accompanying drawings. Though the exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be appreciated that various modifications and configurations to the present invention can be made. Accordingly, the scope of the invention is to be defined solely by the appended claims and equivalents thereof.

0022It must be appreciated that, in the specification and in the appended claims, the singular forms "a," "an" and "the" refer to plural forms unless the context clearly dictates otherwise. Therefore, reference to "the surgical placement" refers to one or more steps and "a therapeutic agent" refers to one or more therapeutic agents.

DEFINITIONS

0023In describing and claiming the invention, the following terminology will be used to denote the definitions set forth below

0024As used herein, "first end," "coronal end," "top end" and "upper end" <b>(111,211,311,411)</b> are used interchangeably to refer to the end of the device that is present above the level of the ring and remains above the bone when implanted into the surgical site.

0025As used herein "first part," "coronal part," "top part" and "upper part" <b>(1A,2A,3A,4A)</b> are used interchangeably to refer to the part of the body of the device that projects above the level of the ring and remains above the bone when implanted into the surgical site.

0026As used herein, "second end," "apical end," "bottom end" and "lower end" <b>(112,212,312,</b> 412) are used interchangeably to refer to the end of the device that is present below the level of the ring and remains below the bone, in contact with the respiratory mucosa when implanted into the surgical site.

0027As used herein, "second part," "caudal part" "bottom part" and "lower part" <b>(1B,2B,3B,4B)</b> are used interchangeably to refer to the part of the body of the device that projects below the level of the ring and remains within the bone when implanted into the surgical site.

0028As used herein "proximal part," and "mesial part" may be used interchangeably to refer to the part which is nearest to the point of reference or the part that is closest to the median plane of the device.

0029As used herein "distal part" refers to the part which is away from the point of reference or the part that is farther away from the median plane of the device.

0030As used herein "cervical third" refers to the upper third part of the lower part of the body of the device that extends from below the level of the ring, or to the upper third part of the body of the device in the form of a dental implant, wherein the body is divided horizontally by imaginary lines into three equal parts.

0031As used herein "middle third" refers to the middle third part of the lower part of the body of the device that extends from below the level of the ring, or to the middle third part of the body of the device in the form of a dental implant, wherein the body is divided horizontally by imaginary lines into three equal parts.

0032As used herein "apical third" refers to the lower third part of the lower part of the body of the device that extends from below the level of the ring, or to the lower third part of the body of the device in the form of a dental implant, wherein the body is divided horizontally by imaginary lines into three equal parts.

0033As used herein, "superior surface" is used to refer to the upper surface of a flat or similar shaped embodiment.

0034As used herein, "inferior surface" is used to refer to the lower surface of a flat or similar shaped embodiment.

0035As used herein, "inlet," and "tubular opening" are used interchangeably to refer to the part of the device that is tubular in shape and is located on the upper part of the device, to which a drug delivery tubing can be attached for drug delivery into the device.

0036As used herein, "central lumen," and "central vent" are used interchangeably to refer to the central hollow space within the body of the device, which further opens to the outside through the inlet on the coronal end and through multiple holes at the apical end.

0037As used herein, "apical wall" is used to refer to the wall comprising the rounded apical end and part of the apical third of the lower part of the device.

0038As used herein, "slot" and "cleft" is used interchangeably to refer to a vertical opening in the upper end of the inlet into which the drug delivery tubing is placed.

0039As used herein, "drug delivery assembly" refers to a hollow tubing comprising a vertical part that is placed into the device and a lateral tube extending from the side of the vertical part, wherein the mesial part of the tube is placed into the slot of an inlet present on the device.

0040As used herein, "intra implant part" refers to the vertical part of the drug delivery assembly that is placed into the device.

0041As used herein, "external drug delivery tubing" or "external tubing" are used interchangeably to refer to the tube extending from the side of the vertical part of the drug delivery assembly that is placed into the slot of an inlet of the device.

0042As used herein, "tubing," and "drug delivery tubing" are used interchangeably to refer to the tube attached to the inlet of the device.

0043As used herein, "intra oral part" refers to the part projecting into or the part facing the oral cavity.

0044As used herein, "intra bony part" refers to the part within the bone or below the level of the bone.

0045As used herein "intra-pulpal part" refers to the part that is within the pulp cavity of the tooth.

0046As used herein, "osseointegration" refers to the process of bone formation around the implant and on the surface of the device facing the bone.

0047As used herein, "abutment," refers to the removable part that can be placed into the device which is in the form of a dental implant. It is in the form of a drug delivery assembly or comprises an internal a drug reservoir with an in-built internal drug infusion pump.

0048As used herein "external involute spline" refers to an involute spline whose tip surface is located on the external surface of the body of the embodiment.

0049As used herein "internal involute spline" refers to an involute spline whose tip surface is located on the internal surface of the body of the embodiment.

0050As used herein, "claw," refers to the curved part of the tool that is used for holding a retention cap by its margin.

0051As used herein, "shaft," refers to the part of the instrument, present between the head and the handle.

0052As used herein, "reservoir," and "drug reservoir" are used interchangeably to refer to a body comprising a cavity that holds a therapeutic agent. The therapeutic agent is in a form in which it can be easily transferred from the reservoir into the device in a controlled and continuous manner. As used herein, "external drug reservoir," refers to a reservoir which is present outside the patient. It is connected to the device in the patient by a tubing whenever drug delivery is required.

0053As used herein, "internal drug reservoir," refers to a reservoir which is present within the implant. It is in the form of a cavity within the abutment.

0054As used herein, "infusion pump," and "drug infusion pump" are used interchangeably to refer to the device that can move the therapeutic agent from the reservoir to the inside of the device in a controlled and continuous manner.

0055As used herein, "therapeutic agent," and "drug" are used interchangeably to refer to an agent or substance that can produce a pharmacologic effect in a human or animal patient when administered into the patient or that is useful as a diagnostic agent when administered in a patient.

0056The surgical steps claimed in the methods, can be executed by changing the order of steps or by avoiding some steps depending on the clinical requirements and are not limited to the order presented in the claims unless otherwise stated. Accordingly, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the descriptions and examples given herein.

DRUG DELIVERY DEVICE:

0057In the preferred embodiment, the single unit implantable device <b>(</b><figref idref="f0001"><b>Fig1</b></figref><b>: A, B, C)</b> has a hollow, cylindrical or tapered body which is closed at both the ends. The body comprises an upper, first part <b>(1A)</b> and a lower, second part <b>(1B),</b> with a barrier ring <b>(103)</b> located on the outer surface of the body between the two parts. The outer surface of the second part <b>(1B)</b> of the body of the device that is located below the circular barrier ring comprises threads <b>(102)</b> from the cervical third to the middle third. The apical part is smooth and has a plurality of holes <b>(101)</b> through the apical wall. The holes are configured in the form of macro-holes, micro-holes, nano-holes or a combination. A central lumen <b>(108)</b> is present within the body. The central lumen extends from the first part <b>(1A)</b> of the body to the second part of the body <b>(1B)</b> and is defined by the internal wall of the device. The porous apical wall is placed either in contact <b>(</b><figref idref="f0011"><b>Fig:11</b></figref><b>)</b> with the connective tissue of the respiratory mucosa or above the level of the epithelial lining <b>(</b><figref idref="f0012"><b>Fig:12</b></figref><b>)</b> of the respiratory mucosa. The first closed <b>(111)</b> end of the device has an external hex <b>(107)</b> for holding and placement of the device. A drug delivery inlet <b>(104)</b> is present below the level of the external hex on the side of the first part <b>(1A)</b> of the body of the device for the attachment of a drug delivery tubing <b>(105).</b> The inlet <b>(104)</b> is configured in the form of an opening with or without internal threads or in the form of a tubular projection. The tubular inlet comprises of either a smooth external surface or a surface with external or internal threads. The tubular inlet is either perpendicular to the external surface of the body of the device or angulated towards the coronal end. The inlet <b>(104)</b> opens into the central lumen <b>(108)</b> present within the body of the device. The central lumen <b>(108)</b> further opens to the exterior through the plurality of holes <b>(101)</b> at the apical wall. A drug delivery tubing <b>(105)</b> is removably secured to the inlet <b>(104).</b> Whenever required, the free, second open end <b>(106)</b> of the drug delivery tubing is connected to a drug infusion source comprising an external drug reservoir attached to an external drug infusion pump for controlled drug delivery. The circular barrier ring <b>(103)</b> is present below the inlet and prevents the accidental inward displacement of the device into the maxillary sinus or into the nasal cavity. The device is made of titanium or any other biocompatible material. The tubing is also made of a resilient and biocompatible material that allows good soft tissue adaptation. The device is manufactured in varying diameters and lengths to suit the different clinical requirements.

0058The device delivers one or more drugs in a controlled and continuous manner, locally at the surgical site in the respiratory mucosal region. The drugs are then transported by neural, vascular, lymphatic or inhalation routes or by a combination of these routes into the brain by bypassing the blood brain barrier.

0059Exemplary, non-limiting embodiments of the brain drug delivery device are illustrated in <figref idref="f0001 f0002 f0003 f0004 f0005 f0006 f0007 f0008 f0009 f0010 f0011 f0012 f0013 f0014 f0015 f0016 f0017 f0018">Fig 1-18</figref>. These figures illustrate variations of the drug delivery device and the methods for use.

0060The preferred embodiment is illustrated in <figref idref="f0001">Figure<b>1</b></figref><b>. Referring to</b><figref idref="f0001"><b>FIG. 1</b></figref><b>Fig: A</b> refers to the isometric side view of the single unit device. <b>101</b> refers to the plurality of holes through the apical wall of the body of the device that is placed either beneath or above the respiratory mucosa. <b>102</b> refers to the threads on the outer surface of the device located at the cervical third and middle third of the second part of the body of the <b>device.103</b> refers to the barrier ring that prevents the unintentional inward displacement of the implant into the maxillary sinus or the nasal cavity.<b>104</b> refers to the inlet.<b>105</b> refers to the drug delivery tubing. The first open end of the tubing is either friction fit or threaded onto or into the inlet <b>(104).</b> The second open end <b>(106)</b> of the tubing is free. <b>110</b> refers to a temporary cap removably coupled to the free second open end of the drug delivery tubing. The second open end can be placed in the buccal sulcus overlying the mucosa, in the buccal gingival sulcus or in the palatal gingival sulcus. <b>107</b> refers to the external hex of the device which removably secures to a holding device and thereby assists in holding and placement of the device into the surgical site. <b>111</b> refers to the first closed end of the device. <b>112</b> refers to the second end of the device. <b>1A</b> refers to the first part of the device. <b>1B.</b> refers to the second part of the device <b>Fig: B</b> refers to the longitudinal sectional view of the device. <b>101</b> refers to the plurality of holes through the apical wall of the device. <b>102</b> refers to the threads on the outer surface of the second part of the device.<b>103</b> refers to the barrier ring.<b>104</b> refers to the inlet to which the drug delivery tubing is connected. <b>107</b> refers to the external hex. <b>108</b> refers to the central lumen. <b>109</b> refers to the external threads on the inlet. <b>Fig: C</b> refers to the 3D rendered view of <b>Fig: A.</b>

0061An alternative embodiment is illustrated in <figref idref="f0002"><b>Fig. 2</b></figref><b>.</b> The alternative embodiment is a multiunit device comprising an inlet <b>(205)</b> located centrally at the first end <b>(211)</b> of the body of the device. The inlet further comprises external threads at its cervical third and a vertical slot extending from its tip to its middle third. The drug delivery assembly comprises an intra implant part <b>(206)</b> and an external tubing <b>(207).</b> The intra implant part is tapering in shape and comprises a central lumen <b>(214)</b> within the body and a plurality of holes <b>(210)</b> through the apical wall. The external tubing <b>(207)</b> is tubular in shape and comprises a central lumen. It extends from the side of the intra-implant part. The central lumen of the intra implant part and that of the external tubing are continuous with each other. When the intra-implant part is inserted into central lumen of the device, the mesial part of the external tubing removably adapts to the vertical slot on the side of the inlet. A cap <b>(209)</b> is threaded onto the external threads on the inlet of the device. The cap covers the slot and extends till the surface of the tubing. The cap retains the intra-implant part within the device. An external hex <b>(204)</b> is present below the inlet. It helps in holding and placing the device. A circular ring <b>(203)</b> is present below the external hex. It prevents the accidental inward displacement of the device into the maxillary sinus or into the nasal cavity. <b>Referring to</b><figref idref="f0002"><b>FIG. 2</b></figref><b>, Fig: A</b> refers to an isometric side view of a multi-unit drug delivery device. <b>211</b> refers to the first open end of the device. <b>212</b> refers to the second end of the device. <b>2A</b> refers to the first part of the device.<b>2B</b> refers to the second part of the device. <b>201</b> refers to the plurality of holes through the apical wall of the body of the device that is placed either beneath or above the respiratory mucosa <b>.202</b> refers to the threads on the outer surface of the device located at the cervical third and middle third of the second part of the body of the device. <b>203.</b> Refers to the barrier ring. <b>204.</b> Refers to the external hex. <b>205</b> Refers to the tubular inlet with external threads.<b>206</b> Refers to the intra implant part of the drug delivery assembly. <b>(215)</b> refers to the first closed end of the intra-implant part of the drug delivery assembly. <b>210</b> refers to the plurality of holes at the apical wall of the intra implant part of the drug delivery assembly.<b>207</b> Refers to the external tubing of the drug delivery assembly.<b>208</b> refers to the open end of the external tubing of the drug delivery assembly <b>213</b> Refers to the cap removably coupled to the open end of the external tubing of the drug delivery assembly <b>209.</b> Refers to the cap with internal threads that can be threaded onto the inlet of the device. It retains the intra implant part of the drug delivery assembly within the device. <b>Fig: B</b> is a longitudinal sectional view of the second part of the device and the components comprised within. <b>201.</b> Refers to the porous apical wall of the device. <b>202.</b> Refers to the external threads on the body of the device <b>203.</b> Refers to the barrier ring. <b>204.</b> Refers to the external hex. <b>206.</b> Refers to the intra implant part of the drug delivery assembly with a central lumen <b>(214)</b> and porous tip. <b>207.</b> Refers to the external tubing of the drug delivery assembly. <b>208</b> refers to the open end of the external tubing of the drug delivery assembly <b>213</b> Refers to the cap removably coupled to the open end of the external tubing of the drug delivery assembly <b>209.</b> Refers to the cap with internal threads that is threaded onto the inlet of the device. It retains the intra implant part of the drug delivery assembly within the device.<b>210.</b> Refers to the porous apical wall of the intra implant part of the drug delivery assembly within the device. <b>Fig: C</b> is a 3D rendered view of Fig A. <b>Fig: D</b> is a 3D rendered view of Fig B.

0062Another alternative embodiment is illustrated in <figref idref="f0003"><b>Fig: 3</b></figref><b>.</b> The alternative embodiment is a multiunit device comprising a completely open second end <b>(312)</b> with a beveled and outwardly flaring internal wall that forms a smooth and rounded margin. <b>(301)</b> and a tubular inlet <b>(305)</b> located centrally at the first end <b>(311)</b> of the body of the device. The inlet further comprises external threads at its cervical third and a vertical slot extending from its tip to its middle third. The drug delivery assembly comprises an intra implant part <b>(306)</b> and an external tubing <b>(307).</b> The intra implant part is tapering in shape and comprises a central lumen <b>(314)</b> within the body and a plurality of holes <b>(310)</b> through the apical wall. The external drug delivery tubing <b>(307)</b> is tubular in shape and comprises a central lumen. It extends from the side of the intra-implant part. The central lumen of the intra implant part and that of the external drug delivery tubing are continuous with each other. When the intra-implant part is inserted into the central lumen of the device, the mesial part of the external tubing removably adapts to the vertical slot on the side of the inlet. The tip of the intra-implant part <b>(306)</b> is positioned at the apical opening of the central lumen and is located below the level of the rounded apical margin. <b>(301).</b> A cap <b>(309)</b> is threaded onto the external threads on the inlet of the device. The cap covers the slot and extends till the surface of the tubing. The cap retains the intra-implant part within the device. An external hex <b>(304)</b> is present below the inlet. It helps in holding and placing the device. A circular ring <b>(303)</b> is present below the external hex. It prevents the accidental inward displacement of the device into the maxillary sinus or into the nasal cavity. <b>Referring to</b><figref idref="f0003"><b>Fig.3</b></figref><b>, Fig: A</b> refers to an isometric side view of a multi-unit implant with a completely open apex <b>311</b> refers to the first open end of the device. <b>312</b> refers to the second open end of the device. <b>3A</b> refers to the first part of the device.<b>3B</b> refers to the second part of the <b>device.301.</b> Refers to the smooth and rounded margins at the completely open second end. <b>302.</b> Refers to the external threads <b>303.</b> Refers to the barrier ring. <b>304.</b> Refers to the external hex. <b>305</b> Refers to the tubular inlet with external threads.<b>306</b> Refers to the intra implant part of the drug delivery assembly. <b>315</b> refers to the first closed end of the intra-implant part of the drug delivery assembly. <b>310</b> refers to the plurality of holes at the apical wall of the intra implant part of the drug delivery assembly. <b>307</b> Refers to the external tubing of the drug delivery assembly. <b>308</b> refers to the open end of the external tubing of the drug delivery assembly.<b>313</b> Refers to the cap removably coupled to the open end of the external tubing of the drug delivery assembly. <b>309.</b> Refers to the cap with internal threads that can be threaded onto the inlet of the device. It retains the intra implant part of the drug delivery assembly within the device. <b>Fig: B</b> is a longitudinal sectional view of the second part of the implant body and the components comprised within. <b>301.</b> Refers to the smooth and rounded margins at the completely open second end of the device <b>302.</b> Refers to the external threads on the body of the device. <b>303.</b> Refers to the barrier ring. <b>304.</b> Refers to the external hex. <b>306.</b> Refers to the intra implant part of the drug delivery assembly with a central lumen <b>314</b> and a porous apical tip which is placed below the level of the margin of the second open end. <b>307.</b> Refers to the external tubing of the drug delivery assembly. <b>308.</b> refers to the open end of the external tubing of the drug delivery assembly.<b>313</b> Refers to the cap at the open end of the external tubing of the drug delivery assembly. <b>309</b>. Refers to the cap with internal threads that is threaded onto the inlet of the device. It retains the intra implant part of the drug delivery assembly within the device.<b>310</b>. Refers to the porous apical wall of the intra implant part of the drug delivery assembly within the device. <b>Fig: C</b> is a 3D rendered view of Fig A. <b>Fig: D</b> is a 3D rendered view of Fig B.

0063An alternative embodiment is illustrated in <figref idref="f0004"><b>Fig.4</b></figref><b>.</b> The alternative embodiment is a multi-unit implantable device with a hollow cylindrical body comprising an upper, first open end <b>(411)</b> and a closed second or apical end <b>(412).</b> The second or apical end is rounded with a plurality of holes <b>(401)</b> through the apical wall and the first or upper end comprises an inlet <b>(405)</b> with internal threads at its cervical third. A barrier ring <b>(403)</b> is present between the inlet <b>(405)</b> and the plurality of the holes <b>(401)</b> on the external surface of the body of the device and comprises a convex and smooth upper surface and a flat and smooth undersurface facing the bone. The external surface of the first or upper part <b>(4A)</b> of the body further comprises an external hex <b>(404)</b> disposed between the drug delivery inlet <b>(405)</b> and the barrier ring <b>(403).</b> A central lumen is present within the body of the device and is defined by the tapering internal wall of the body of the device. The central lumen extends from the inlet <b>(405)</b> at the upper, first end to the plurality of holes <b>(401)</b> in the apical wall. Threads <b>(402)</b> are present on the external surface of the second or lower part <b>(4A)</b> of the body at the cervical third, below the level of the ring. The drug delivery assembly comprises a tapered intra-implant part <b>(406)</b> with external threads <b>(414)</b> at its upper part and an external drug delivery tubing <b>(407)</b> attached to the first end <b>(415)</b> of the intra-implant part. The intra-implant part <b>(406)</b> of the drug delivery assembly is threaded into the inlet <b>(405)</b> of the device wherein the external walls of the intra implant part adapt tightly to the internal walls of the device except at the apical third. A space is present at the apical third between the internal wall of the device and the external wall of the intra-implant part, wherein the drug is initially delivered. The drug further moves out through the holes <b>(401)</b> at the apical wall of the device. <b>Referring to</b><figref idref="f0004"><b>Fig.4</b></figref><b>, Fig: A</b> refers to an isometric side view of a multi-unit device with the tubular central inlet with internal threads at the first end. <b>411</b> refers to the first open end of the device. <b>412</b> refers to the second end of the device. <b>4A</b> refers to the first part of the device. <b>4B</b> refers to the second part of the device. <b>401.</b> Refers to the porous apical wall of the device. <b>402.</b> Refers to the external threads <b>403.</b> Refers to the barrier ring. <b>404.</b> Refers to the external hex. <b>405</b> Refers to the tubular inlet with internal threads. <b>406</b> Refers to the intra implant part of the drug delivery assembly. <b>(415)</b> refers to the first end of the intra implant part of the drug delivery assembly. <b>407</b> Refers to the external tubing of the drug delivery assembly. <b>408</b> refers to the open end of the external tubing of the drug delivery assembly.<b>413</b> Refers to the cap removably coupled to the open end of the external tubing of the drug delivery assembly. <b>409</b> refers to the external hex at the first end of the intra implant part <b>410.</b> Refers to the porous apical wall of the intra implant part of the drug delivery assembly. <b>414</b> Refers to the external threads on the intra-implant part of the drug delivery assembly. The intra-implant part is threaded into the inlet of the device. <b>Fig: B</b> is a 3D rendered view of Fig A.

0064The drug delivery device is held and placed in the surgical site using specialized holding devices because of the limited anatomical space available for use and the need for sterilized instruments. The instruments are configured as hand held or as motor driven rotary instruments. The hand-held instruments are in the form of ratchets or spanners of varying sizes and length. The holding devices basically consist of a head and a handle. The head adapts to the external hex present on the drug delivery device or on the retention cap. The head is of varying diameters. The handle is of varying lengths and angulations. The handle is either hand held or attached to a low-speed motor driven rotary handpiece. The embodiments are illustrated in <figref idref="f0005">Figure 5</figref>. <b>Referring to</b><figref idref="f0005"><b>FIG. 5</b></figref><b>, 5X</b> refers to the external hex on the device <b>Fig: A</b> Refers to the spanner for placement and removal. <b>501.</b> Refers to the head which adapts to the external hex on the device. <b>502.</b> Refers to the handle. <b>Fig: B</b> Refers to an angulated spanner. <b>503.</b> Refers to the head which adapts to the external hex on the device. <b>504.</b> Refers to the angulated handle. <b>Fig: C</b> refers to the hand-held ratchet. <b>505.</b> Refers to the head which adapts to the external hex on the device. <b>506.</b> Refers to the handle. <b>Fig: D</b> refers to an angulated hand-held ratchet. <b>507.</b> Refers to the head which adapts to the external hex on the device. .<b>508</b>. Refers to the angulated handle. <b>Fig: E</b> refers to a hand-held rotating placement and removal tool. <b>509.</b> Refers to the head which adapts to the external hex on the device. <b>510.</b> Refers to the rotating finger rest. <b>Fig: F</b> refers to a motor driven rotary placement and removal tool. <b>511.</b> Refers to the head which adapts to the external hex on the device. <b>512.</b> Refers to the free end of the shank that can fit into the rotary instrument.

0065Another embodiment is illustrated in <figref idref="f0006"><b>Fig. 6</b></figref><b>.</b> In this embodiment, the device is in the form of a hollow dental implant made of titanium alloy or any other biocompatible material. The implant comprises external threads <b>(602)</b> on the body. The implant has micro holes <b>(601)</b> at the apical part of the implant body. The central lumen <b>(619)</b> of the implant is defined by the internal surface of the implant and communicates with the nasal respiratory mucosa or the maxillary sinus lining mucosa through the holes <b>(601)</b> at the apical part of the body of the implant. The implant has an internal involute spline <b>(618)</b> within the implant body. The implant has internal threads <b>(617)</b> at the cervical end. The disposable abutment made of a bio-compatible material has a body comprising an intra-oral part <b>(607)</b> and an intra-implant part <b>(605)</b> with a barrier ring <b>(606)</b> disposed on the external surface between the two parts. The external surface of the intra-implant part of the abutment has an external involute spline <b>(623)</b> and a micro-porous apical wall <b>(604).</b> The abutment further comprises a central lumen that communicates to the exterior through an external drug delivery tubing <b>(611)</b> that extends from the first end <b>(624)</b> of the abutment. The external involute spline <b>(623)</b> of the abutment fits into internal involute spline <b>(618)</b> of the dental implant. The plurality of holes <b>(604)</b> at the apical wall of the abutment is in alignment and in line with the plurality of holes <b>(601)</b> at the apical wall of the implant. A cap <b>(609)</b> comprising an external hex <b>(610)</b> with a central hole at the upper first part and external threads <b>(608)</b> at the lower second part is slid from the top of the abutment and threaded into the inner threads <b>(617)</b> at the cervical part of the implant. The inner aspect of the cap adapts closely and tightly to the outer surface of the abutment to form a tight junction without any micro-leakage. The cap <b>(609)</b> of the device is of variable heights depending on the soft tissue requirements and is well adapted to the wall of the abutment on tightening. The drug is delivered into the central lumen of the abutment through the external drug delivery tubing <b>(611)</b> extending from the first end of the abutment. <b>Fig: A</b> refers to the isometric side view of the dental implant <b>601</b> refers to the holes in the apical wall of the implant.<b>602</b> refers to the external threads on the implant<b>.603</b> refers to the smooth cervical end.<b>604</b> refers to the holes in the apical wall of the <b>abutment.605</b> refers to the intra implant part. <b>623</b> refers to the external involute spline on the abutment <b>.606</b> refers to the barrier ring <b>.607</b> refers to the intra-oral part of the abutment.<b>608</b> refers to the external threads on the cap. <b>609</b> refers to the cap.<b>610</b> refers to the external hex on the cap. <b>624</b> refers to the first end of the abutment.<b>611</b> refers to the external drug delivery tubing. <b>612</b> refers to the distal free end of the external drug delivery tubing. <b>622</b> refers to the cap removably coupled to the open end of the external drug delivery tubing. <b>620</b> refers to the first open end of the device. <b>621</b> refers to the second end of the device. <b>Fig: B</b> refers to the 3 D rendered view of Fig A. <b>Fig: C</b> refers to the isometric side view of the dental implant and the placement tool. <b>601</b> refers to the holes in the apical wall of the implant.<b>602</b> refers to the external threads on the implant.<b>603</b> refers to the smooth cervical end.<b>613</b> refers to the external involute spline on the placement tool <b>.614</b> refers to the barrier ring on the placement tool <b>.615</b> refers to the shank of the placement tool.<b>616</b> refers to the external hex on the hand-held placement tool. <b>Fig: D</b> refers to the 3 D rendered view of Fig C. <b>613</b> refers to the external involute spline on the placement tool <b>.614</b> refers to the barrier ring on the placement tool <b>.615</b> refers to the shank of the placement tool.<b>616</b> refers to the external hex on the hand-held placement tool. <b>617</b> refers to the internal cervical threads at the first open end of the implant. <b>618</b> refers to the internal spline within the implant. <b>619</b> refers to the central lumen within the implant.

0066Alternative embodiments of the abutment, for use with the device in the form of a dental implant are illustrated in <figref idref="f0007"><b>Fig 7</b></figref><b>.</b> Referring to <figref idref="f0007"><b>Fig: 7</b></figref><b>, Fig A</b> is a 3D rendered view of the abutment. <b>711</b> refers to the first end of the abutment. <b>712</b> refers to the second end of the abutment. <b>702</b> refers to the first part or the intra-oral part of the abutment. 713 refers to the second part or the intra-implant part of the abutment. <b>701</b> refers to the inlet in the first end of the abutment. A drug delivery tubing is removably secured to the inlet. <b>703</b> refers to the barrier <b>ring.704</b> refers to the external involute spline. <b>705</b> refers to the openings in the apical wall. <b>Fig B</b> is the longitudinal section of Fig A. <b>706</b> refers to the central lumen within the body of the implant. In another alternative embodiment, specially designed abutments in the form of drug reservoirs comprising in-built, miniature, osmotically or electronically controlled infusion pumps are used for drug delivery with the device. <b>Fig C</b> refers to the abutment comprising a drug reservoir in the second part, a space to hold an injected osmotic solvent in the first part and an osmotic compartment holding the osmotic agent disposed between the first and the second part. A semipermeable membrane separates the osmotic agent from the space in the first part. When the solvent is injected into the space in the first part, the solvent moves across the semipermeable membrane into the osmotic compartment and causes it to expand, thereby pushing the drug out from the reservoir at a predetermined rate through the apical holes.<b>701</b> refers to the inlet in the first end of the abutment through which the osmotic solvent is delivered. <b>702</b> refers to the intra-oral part of the abutment that holds the osmotic solvent. <b>703</b> refers to the barrier ring. <b>705</b> refers to the openings in the apical wall. <b>707</b> refers to the semipermeable membrane separating the osmotic agent from the space in the first part of the abutment.<b>708</b> refers to the osmotic compartment.<b>709</b> refers to the drug reservoir. <b>Fig D</b> refers to the abutment comprising a drug reservoir in the second part and an electronic drug infusion pump in the first part. <b>702</b> refers to the intra-oral part of the abutment that holds the electronic drug infusion pump. <b>703</b> refers to the barrier ring. <b>705</b> refers to the openings in the apical wall. <b>709</b> refers to the drug reservoir. <b>710</b> refers to the electronic drug infusion pump. The abutment is also used as a drug reservoir for continuous drug delivery, by modifying the size of the plurality of holes at the apical part of the abutment into holes that equal the size of the drug molecule. This results in delivery of the drug molecules at a pre-determined rate. <b>Fig E</b> refers to the abutment used as an internal drug reservoir. <b>702</b> refers to the first part or the intra-oral part of the abutment. <b>703</b> refers to the barrier ring. <b>705</b> refers to the openings in the apical wall. <b>709</b> refers to the drug reservoir compartment extending from the first part to the second part of the abutment. The intra oral part of the abutment is angulated above the level of the cap <b>(809).</b> The inlet on the abutment is also in the form of an opening with internal threads and located on the side of the intra-oral part.

0067In the case of preparing the surgical site on the maxillary alveolar process, an osteotomy dental drill of appropriate length and diameter is used. The osteotomy is stopped short by 1mm of the maxillary sinus lining mucosa or the nasal respiratory mucosa. The apical 1mm of bone is gently broken with a bone compression tool or with an elevator by gentle tapping. Care is taken not to tear the respiratory mucosa in the nasal or the maxillary sinus region. Placement of the device in the form of a dental implant into the alveolar bone using the required instruments is illustrated in <figref idref="f0008"><b>FIG. 8</b></figref><b>. 801.</b> Refers to the ratchet for holding the bone compression tool. <b>802</b> refers to the bone compression tool being used for enlarging the soft osteotomy site and for breaking the apical wall to access the respiratory mucosa.<b>803</b> refers to the osteotomy site in the maxillary region underlying the respiratory mucosa.<b>804</b> refers to the holes in the apical wall of the implant. <b>805</b> refers to the body of the implant being placed into the osteotomy site. <b>806</b> refers to the placement tool used for placing the device into the osteotomy. <b>807</b> refers to the ratchet for holding the placement tool. <b>808</b> shows the abutment placed into the device. <b>809</b> shows the cervical retention cap comprising a central hole being placed across the intra oral part of the abutment. The cap further comprises a plurality of holes disposed on the superior surface of the upper part. <b>810</b> refers to the projections at the tip of the placement tool that removably secure to the holes on the superior surface of the upper part of the cap. <b>811</b> refers to the body of the placement tool.<b>812</b> refers to the rotating finger rest on the placement tool. <b>813</b> refers to the claw of the removal tool.<b>814</b> refers to the handle of the removal tool. <b>815</b> Refers to the vertically moveable shank of the device<b>.816</b> refers to the rotating finger rest on the removal tool. <b>817</b> refers to the inlet in the upper end of the abutment. <b>818</b> refers to the maxillary sinus or the nasal cavity comprising respiratory lining mucosa.

0068Another embodiment illustrated in <figref idref="f0009"><b>Fig. 9</b></figref><b>.</b> is an implantable drug delivery device that comprises a mini plate with a central drug reservoir dial, wherein the reservoir has a porous base, a body with parallel walls, external or internal threads at the top part of the dial wall and a cap with complimentary internal or external threads made of a resilient, biocompatible material that self-seals whenever penetrated by a needle. The porous base of the drug reservoir dial comprises macro holes, micro holes or nano holes and is placed beneath or above the respiratory mucosa. The drug is delivered into the drug reservoir dial using a needle that is connected to a syringe or an external drug infusion pump. The needle penetrates the cap and deposits the drug into the drug reservoir dial. Alternatively, a reservoir containing a drug with a rate limiting membrane at the base can also be placed into the dial. The drug reaches the respiratory mucosa through the holes in the base of the drug reservoir dial. The mini plate is secured to the bone by screws. <b>Referring to</b><figref idref="f0009"><b>FIG: 9</b></figref><b>, Fig</b> A shows the top view of a mini plate that comprises a central drug reservoir dial with a microporous or nanoporous apical wall at the second end and straight limbs. <b>901</b> refers to the straight limb with screw holes. <b>902</b> refers to the inlet at the first open end of the central drug reservoir dial with internal or external threads. A cap <b>(906)</b> with complimentary threads is secured to the inlet of the drug reservoir dial. <b>903</b> refers to the micro-porous or nanoporous apical wall at the second end of the drug reservoir dial. The drug is deposited into the dial. <b>908</b> refers to the retention screw. <b>Fig B</b> shows a top view of the mini plate that comprises a central drug reservoir dial with a microporous or nanoporous apical wall at the second end and a left L shaped limb. <b>901</b> refers to the straight limb with screw holes. <b>902</b> refers to the inlet at the first open end of the central drug reservoir dial with internal or external threads. A cap with complimentary threads is secured to the inlet at the first open end of the drug reservoir dial <b>903</b> refers to the micro-porous or nanoporous apical wall at the second end of the drug reservoir dial. The drug is deposited into the dial. <b>904</b> refers to the left L shaped limb with screw holes. <b>Fig C</b> shows the top view of a mini plate that comprises a central drug reservoir dial with a microporous or nanoporous apical wall at the second end and a right L shaped limb. <b>901</b> refers to the straight limb with screw holes. <b>902</b> refers to the inlet at the first open end of the central drug reservoir dial with internal or external threads. A cap with complimentary threads is secured to the inlet at the first open end of the drug reservoir dial <b>903</b> refers to the micro-porous or nanoporous apical wall at the second end of the drug reservoir dial. The drug is deposited into the dial. <b>904</b> refers to the right L shaped limb with screw holes. <b>Fig D</b> shows the cap made of a resilient, biocompatible material that self-seals whenever penetrated by a needle. <b>905</b> refers to the holes used for holding the cap while threading it onto the reservoir dial. <b>906</b> refers to the self-sealing part of the cap into which needles can be inserted. <b>907</b> refers to the threads on the cap. The threads can be external or internal.

0069An alternative embodiment comprises a mini plate with a central reservoir dial wherein the reservoir has a porous base, an angulated body and a cap made of a resilient, biocompatible material that self-seals whenever penetrated by a needle. The upper end of the cap has an external hex and the lower part of the cap has internal or external threads. The angulation helps in ease of placing the needle tip into the reservoir for drug delivery from the oral cavity, when the mini plate is located on concave surfaces like the anterior wall of the maxillary sinus. The alternative embodiment is herein illustrated in <figref idref="f0010">Figure10</figref>. <b>Referring to</b><figref idref="f0010"><b>FIG: 10</b></figref><b>, Fig</b> A shows the side view of a mini plate with a central drug reservoir dial, comprising a hollow body with an angulated first part and a perpendicular second part, a straight limb and an L shaped limb between the two parts of the dial. <b>1001</b> refers to the straight limb with screw holes. <b>1002</b> refers to angulated part of the central drug reservoir dial comprising an inlet with internal or external threads at the first open end. <b>1003</b> refers to the cap with threads <b>1004</b> refers to the perpendicular second part of the reservoir dial comprising a micro-porous or nanoporous apical wall at the second end that is placed below the respiratory mucosa. <b>1006</b> refers to the retention screw. Fig <b>B</b> shows the top view of a mini plate with a central drug reservoir dial, comprising a hollow body with an angulated first part and a perpendicular second part with straight limbs between the two parts of the dial. <b>1001</b> refers to the straight limb with screw holes. <b>1002</b> refers to angulated part of the central drug reservoir dial comprising an inlet with internal or external threads at the first open end. <b>1003</b> refers to the cap with threads. <b>1006</b> refers to the retention screw. <b>Fig C and D</b> show the top view of a mini plate with a central angulated drug reservoir dial comprising a straight limb and an L shaped limb. <b>1001</b> refers to the straight limb with screw holes. <b>1002</b> refers to angulated part of the central drug reservoir dial comprising an inlet with internal or external threads at the first open end. <b>1003</b> refers to the cap with threads <b>1005</b> refers to the L shaped limb. It points either to the right or to the left. <b>1006</b> refers to the retention screw.

II. METHOD FOR DRUG DELIVERY:

A. SURGICAL PREPARATION OF THE IMPLANTATION SITE

0070A full thickness buccal or palatal mucoperiosteal flap is elevated. A bone window is marked on the bone overlying the respiratory mucosa using a bone trephine drill of appropriate length and diameter. The bone window can be surgically prepared at a number of anatomical sites which also include the hard palate forming the floor of the maxillary sinus or the nasal cavity, anterior wall of the maxillary sinus or the zygomatic process of the maxilla. The bone window can be gently pried out with the rotating trephine drill without damaging the underlying respiratory mucosa. Alternatively, the circumscribed bone can be removed gently without damaging the underlying mucosa using a piezo instrument. The respiratory mucosa is gently released and elevated from the surrounding bone margins without tearing the respiratory mucosa by using a soft tissue elevator of appropriate diameter.

0071In the case of preparing the surgical site on the maxillary alveolar process, an osteotomy dental drill <b>(802)</b> of appropriate length and diameter is used. The osteotomy <b>(803)</b> is stopped short by 1mm of the maxillary sinus lining mucosa or the nasal respiratory mucosa. The apical 1mm of bone is gently broken with a bone compression tool or with an elevator by gentle tapping. Care is taken not to tear the respiratory mucosa in the nasal or the maxillary sinus region.

B. SURGICAL PLACEMENT OF THE IMPLANT

0072A ratchet or implant placement tool <b>(</b><figref idref="f0005"><b>Fig 5</b></figref><b>: A, B, C, D, E, F)</b> which fits onto the external hex <b>(1110; 1210)</b> on the implant is used to hold and place the implant. The implant of the correct diameter and length is gently threaded into the prepared osteotomy site using a hand-held ratchet or a rotary placement tool. Alternatively, the implant can be gently press fit into the osteotomy hole. The barrier ring <b>(1107;1207)</b> prevents the accidental displacement of the implant into the maxillary sinus or the nasal cavity. The respiratory lining mucosa <b>(1101)</b> is further elevated by the smooth apical end of the implant. The porous apical part <b>(1102)</b> of the hollow implant is thus in contact with the connective tissue base of the respiratory lining mucosa. The drug delivery assembly or the delivery tubing <b>(1108)</b> is attached to the implant at the inlet. The elevated soft tissue flap is placed back in position and sutures are placed. The surgical site is allowed to heal. The second open end of the drug delivery tubing can be placed in the buccal sulcus overlying the oral mucosa, in the buccal gingival sulcus or in the palatal gingival sulcus. The second open end of the tubing <b>(1109)</b> can be closed with a temporary cap <b>(1111).</b> After adequate healing of the surgical site, whenever drug delivery is required, the cap is removed and the second open end of the tubing can be attached to a drug infusion source comprising an external drug infusion pump <b>(1305)</b> and an external drug reservoir for controlled drug delivery.

C. LOCATION OF THE APICAL POROUS TIP OF THE DEVICE WITH RESPECT TO THE RESPIRATORY MUCOSA

0073<b>.</b> The porous apical wall of the device is surgically placed beneath the intact respiratory mucosa at a number of anatomical sites which also include the maxillary sinus, hard palate forming the floor of the nasal cavity or maxillary sinus, the zygomatic process of the maxilla or the nasopalatine foramen. The drug can be delivered in a continuous and controlled manner into the connective tissue side of the respiratory mucosa through the plurality of holes in the apical wall of the hollow device, by connecting the drug delivery tubing of the device to an external drug reservoir that is attached to a drug infusion pump. The drug distributes into the brain by bypassing the blood brain barrier from the delivery site without significant increase in the concentration of the drug in the peripheral circulation. The drug delivery route into the brain is either through the neural, lymphatic or the vascular route or a combination of all the routes. This is useful for drugs which need to be given in precise concentrations and in low volumes. Drugs can thus be delivered into the brain by bypassing the blood brain barrier.

0074Referring to <figref idref="f0011"><b>FIG. 11</b></figref><b>:</b> Fig: A refers to the isometric view of the maxillofacial implantable drug delivery device placed beneath the nasal respiratory mucosa or the maxillary sinus lining <b>mucosa.1101</b> refers to the respiratory mucosal lining. <b>1102</b> refers to the smooth porous apical wall of the device. <b>1103</b> refers to the drug delivered under the respiratory mucosa. <b>1104</b> refers to the surrounding alveolar bone.<b>1105</b> refers to the overlying oral mucosa.<b>1106</b> refers to the threads on the outer surface of the <b>device.1107</b> refers to the barrier ring.<b>1108</b> refers to the drug delivery tubing. <b>1109</b> refers to the second open end of the drug delivery tubing.<b>1110</b> refers to the external hex.<b>1111</b> refers to the cap. <b>Fig B</b> is a 3D rendered view of Fig A.

0075<b>.</b> The porous apical tip of the device is placed into the maxillary sinus and above the level of the epithelial lining of the respiratory mucosa by perforating the respiratory mucosa from underneath or the connective tissue side. The drug can be delivered from an external drug reservoir into the maxillary sinus and onto the epithelial surface of the mucosal lining, in a continuous and controlled manner through the plurality of holes at the apical wall of the device by using an external drug infusion pump. The drug can then be easily inhaled during inspiration since the air in the normal maxillary sinus empties during routine inspiration and fills with air during expiration. The inhaled drug can be further deposited on the nasal respiratory and olfactory mucosa for absorption. Moreover because of the muco-ciliary action, the drug can also be transported from the maxillary sinus onto the nasal respiratory mucosa through the ostial opening at the middle meatus. This drug can further be inhaled to reach the olfactory mucosa also. Because of the extra time taken for muco ciliary clearance from the maxillary sinus to the nasal respiratory mucosa, the retention time of the drug on the mucosal surface is increased, resulting in absorption of higher quantity of the drug. This route is useful for drug formulations that are inhalable and can be given in larger volumes without causing systemic or local complications.

0076Referring to <figref idref="f0012"><b>Fig 12</b></figref><b>:</b> Fig: A refers to the isometric view of the maxillofacial implantable drug delivery device placed into the maxillary sinus with the tip above the level of the epithelial lining of the lining respiratory mucosa.<b>1201</b> refers to the respiratory mucosal lining. <b>1202</b> refers to the smooth microporous apical wall of the device. <b>1203</b> refers to the drug delivered above the respiratory mucosa.<b>1204</b> refers to the surrounding alveolar bone.<b>1205</b> refers to the overlying oral mucosa. <b>1206</b> refers to the threads on the outer surface of the device <b>1207</b> refers to the barrier ring.<b>1208</b> refers to the drug delivery tubing <b>.1209</b> refers to the second open end of the drug delivery tubing. <b>1210</b> refers to the external hex. <b>1211</b> refers to the cap. <b>Fig B</b> is a 3D rendered view of Fig A.

D. CONTROLLED AND CONTINUOUS DRUG DELIVERY.

0077The second open end of the drug delivery tubing which is located over the oral mucosa in the buccal sulcus, at the buccal gingival sulcus or the palatal gingival sulcus is connected to a drug infusion source comprising an external reservoir attached to an external a drug infusion pump. The external electronically controlled infusion pump provides a continuous and controlled rate of delivery of drugs at the range of milliliters, microliters or nanoliters into the implant. This is essential to provide drug delivery without traumatizing the respiratory mucosa, to prevent backflow of drug from the device due to high rate of drug inflow and to prevent leakage or overflow of the drug across the mucosal delivery site due to high rate and large volume of drug delivery at the implant-mucosal interface. The preferred method is illustrated in <figref idref="f0013"><b>Fig: 13</b></figref><b>. Fig A</b> shows the device placed at the anterior wall of the maxillary sinus. <b>1301</b> refers to the barrier ring. <b>1302</b> refers to the external hex. <b>1303</b> refers to the drug delivery tubing. <b>1304</b> refers to the cap <b>Fig B</b> shows the device connected to an external drug reservoir attached to an external a drug infusion pump. <b>1305</b> refers to the external drug infusion pump comprising an external drug reservoir that is attached to the second open end of the drug delivery tubing of the device.

0078Alternatively, as in <figref idref="f0007"><b>Fig: 7</b></figref><b>: C and D,</b> an abutment comprising an internal drug reservoir <b>(709)</b> at the intra-implant part <b>(713)</b> which is controlled by a miniature drug infusion pump <b>(710)</b> located in the intra-oral part <b>(702),</b> can be used with the device in the form of a dental implant <b>(805)</b> for controlled and continuous drug delivery. This system can be used when the device is placed into the alveolar ridge <b>(803),</b> small quantity of drug has to be delivered over a period of time, and access is available to change the abutment after the drug is delivered. Alternatively, <b>as in</b><figref idref="f0007"><b>Fig :7</b></figref><b>: E,</b> the abutment is used as a drug reservoir <b>(709)</b> for continuous drug delivery, by modifying the plurality of holes <b>(705)</b> at the apical part of the abutment into holes that equal the size of the drug molecule. This results in delivery of the drug molecules at a pre-determined rate.

E. OPTIONAL PROCEDURES FOR DIFFERENT CLINICAL SITUATIONS

0079In case of emergency, the drug can be directly delivered beneath the respiratory mucosa on the connective tissue side using the drug delivery assembly which is connected to an external drug reservoir attached to an external a drug infusion pump.

0080A biocompatible cement can be applied to the undersurface of the barrier ring of the implant to fix the barrier ring to the underlying bone. This retains the implant in position and prevents movement during immediate drug delivery.

0081The barrier ring of the device can also be configured with screw holes at the periphery or with retentive limbs containing screw holes. Mini screws can be placed in the holes to secure the device to the bone.

0082In another alternative embodiment as illustrated in <figref idref="f0014"><b>Fig: 14</b></figref><b>,</b> a device in the form of a prosthetic crown <b>(1410)</b> secured to a root canal treated tooth <b>(1408)</b> whose apex <b>(1402)</b> is in contact with the respiratory mucosa <b>(1401)</b> is used as a drug delivery device. After biomechanical preparation of the pulp cavity <b>(1406;1403)</b> of the tooth till the apex, the coronal part of the tooth <b>(1408)</b> is prepared for the crown. An additional vertical slot <b>(1407)</b> is prepared on the tooth extending from the occlusal surface to the middle part of buccal or palatal wall. A crown <b>(1410)</b> is made using a biocompatible material. A cylindrical tube open at both the ends is included as a part in the crown at the middle third of the palatal or buccal wall, further wherein the intra oral end of the tube <b>(1409)</b> that opens into the oral cavity at the buccal or palatal side has internal threads and the intra pulpal end of the tube that opens into the pulp chamber is smooth with a straight or an apically curved end. The part of the crown with the cylindrical tube is slid into the vertical slot <b>(1407)</b> in the coronal part of the tooth during the cementation of the crown. A drug delivery tubing is threaded into the open end <b>(1409)</b> of the inlet tube on the buccal or palatal side for drug delivery. The opening is closed with a disposable cap <b>(1413)</b> when not in use. <figref idref="f0014"><b>Fig: 14</b></figref> shows an upper molar with its root tips in close proximity to the overlying maxillary sinus lining mucosa. <b>1401</b> refers to the maxillary sinus lining.<b>1402</b> refers to the opening at the root <b>apex.1403</b> refers to the enlarged and debrided pulp canal.<b>1404</b> refers to the alveolar bone.<b>1405</b> refers to the gingiva. <b>1406</b> refers to the pulp chamber. <b>1407</b> refers to the vertical slot on the buccal wall.<b>1408</b> refers to the coronal part of the tooth prepared for receiving the prosthetic crown.<b>1409</b> refers to the drug delivery inlet on the prosthetic crown. <b>1410</b> refers to the body of the prosthetic crown. <b>1411</b> refers to the first end of the crown. <b>1412</b> refers to the second end of the crown. <b>1413</b> refers to the disposable cap.

0083In cases where the device is in the form of a dental implant <b>(</b><figref idref="f0006"><b>Fig 6</b></figref><b>: A B C D;</b><figref idref="f0008"><b>Fig 8</b></figref><b>: A, B)</b> that is placed into the alveolar ridge <b>(803),</b> a dental crown with a buccal or palatal inlet is used with an abutment that also has a corresponding inlet opening on the side of the intra-oral part. Drug is delivered into the implant through the inlet in the abutment which in turn is accessed through the inlet in the buccal or palatal wall of the crown. The inlet opening in the crown is closed with a screw when not in use for drug delivery.

0084In cases where mini plates <b>(</b><figref idref="f0009"><b>Fig:9</b></figref><b>: A, B, C;</b><figref idref="f0010"><b>Fig 10</b></figref><b>: A, B, C, D)</b> with drug reservoir dials <b>(902,1002)</b> are used, a full thickness mucosal flap is elevated. Appropriate diameter of bone is removed with a bur or a piezo instrument, without damaging the overlying respiratory epithelium. The dial is placed into the osteotomy with its porous base <b>(903,1004)</b> in contact with the respiratory mucosa. The mini plate is fixed to the bone by mini screws <b>(908,1006).</b> The top of the dial is closed with a threaded cap <b>(906,1003)</b> which is biocompatible and self-seals when penetrated by a needle. The flap is replaced over the reservoir and allowed to heal. Drug can be injected into the reservoir dial space using a needle from the overlying anaesthetized mucosa whenever needed.

F. APPLICATIONS OF THE DELIVERY DEVICE

0085The brain drug delivery implant can be used for a single dose of drug delivery and then removed or can be retained at the anatomical site for a longer period of time if multiple doses of the drug are required. A single drug or a combination of drugs can be delivered. Stem cells and small interference RNAs can also be delivered into the brain using this device and the methods.

0086Hence this this device and the methods can be used to deliver the drugs into the brain bypassing the blood brain barrier in patients with Alzheimer, Parkinson, Drug addiction, Cancer, White matter disease, Pain management, Brain infections, Psychiatric conditions and a myriad of other relevant medical conditions.

0087The brain drug delivery device and the methods of drug delivery thereof will be further understood by reference to the following non-limiting examples.

Example1

CONTROLLED AND CONTINUOUS DELIVERY OF DRUGS BENEATH THE RESPIRATORY MUCOSA

0088The device was surgically placed in a rabbit in the maxillary sinus region by removing the bone overlying the respiratory mucosa. The tip of the device was placed beneath the maxillary sinus lining mucosa in contact with the connective tissue side of the mucosa. Dopamine was infused in a controlled and continuous manner under the maxillary sinus mucosa of the rabbit for twenty minutes at the rate of 1 milliliter per hour by using an external drug infusion pump connected to the implanted device. Whole body perfusion was done using a peristaltic pump with warm physiological saline for 20 minutes at a controlled rate. The perfused brain was then resected at the end of one hour from the start of the procedure. Brain samples from different parts of the brain was were analyzed using High Performance Liquid Chromatography. There was an increased concentration of dopamine in all parts of the brain except diencephalon when compared with the normal. Thus, the drug had bypassed the blood brain barrier. <figref idref="f0015"><b>Fig: 15</b></figref> refers to the comparative brain values of dopamine using High Performance Liquid Chromatography, between the control and the rabbit in which dopamine was delivered in vivo in a continuous and controlled manner under the maxillary sinus mucosa using the drug delivery system. During the procedure, a blood sample was collected before drug delivery. Three blood samples were then collected at intervals of 10, 20 and 30 minutes respectively following start of drug delivery. The samples were analyzed using High Performance Liquid Chromatography. The blood values dipped during drug delivery at the 10- and 20-minute interval. The drug delivery was stopped at the twentieth minute. Subsequently the blood value peaked again at the 30-minute interval. <figref idref="f0016"><b>Fig: 16</b></figref> refers to blood values of dopamine in the rabbit after in vivo delivery of dopamine under the maxillary sinus mucosa using the device. This shows that dopamine delivered using the device had reached the brain by bypassing the blood brain barrier and may have effected a low dopamine peripheral response by a feedback mechanism in the brain during drug delivery. The peripheral value would have increased after the central negative feedback control had ceased once the drug delivery was stopped. Moreover, there was no increase of the drug in peripheral circulation during drug delivery.

Example2

CONTROLLED AND CONTINUOUS DELIVERY OF DRUGS ABOVE THE RESPIRATORY MUCOSA

0089The device was placed into the maxillary sinus of a rabbit by perforating the maxillary sinus mucosa from the connective tissue side and placing the implant tip into the sinus cavity and above the epithelial layer. Lignocaine was infused in a controlled and continuous manner for twenty minutes at the rate of 1.5 milliliter per hour by using an external drug infusion pump connected to the implanted device. Whole body perfusion was done using a peristaltic pump with warm physiological saline for 20 minutes at a controlled rate. The perfused brain was then resected at the end of one hour from the start of the procedure. Brain samples from different parts of the brain were analyzed using High Performance Liquid Chromatography. There was an increased concentration of Lignocaine in some parts of the brain as shown in the <figref idref="f0017"><b>Fig: 17</b></figref><b>.</b> Thus the drug had bypassed the blood brain barrier. But the tissue distribution was lesser and the tissue concentration was less when compared to a similar volume of the drug delivered beneath the respiratory mucosa. During the procedure, a blood sample was collected before drug delivery. Three blood samples were then collected at intervals of 10, 20 and 30 minutes respectively following start of drug delivery. The samples were analyzed using High Performance Liquid Chromatography. There was no drug in the peripheral circulation. <figref idref="f0018"><b>Fig: 18</b></figref> refers to the blood values of Lignocaine in the rabbit after the in vivo delivery of Lignocaine into the maxillary sinus cavity and onto the epithelial surface of the maxillary sinus mucosa using the device

0090The above-mentioned methods and device are only illustrative of the principle of the present invention. Modifications and variations of the methods and devices including but not limited to, variations in size, materials, shape, assembly, function, use and mode of operation will be obvious to those of ordinary skill in the art from the foregoing detailed description. Such modifications and variations made herein come within the scope of the appended claims.