Sustained release formulations comprising lamotrigine

The present invention relates to a sustained release formulation containing lamotrigine.

Lamotrigine, 3,5-diamino-6 (2,3-dichlorophenyl) -1,2,4-triazine, is disclosed in US Patent Nos. 4,602,017 and EP 0021121. Products including lamotrigine are sold by the GlaxoSmithKline group of companies under the tradename LAMICTAL ™. Such products are particularly effective in the treatment of CNS disorders, especially epilepsy, pain, edema, multiple sclerosis, and in the treatment of psychiatric indications including bipolar disorder.

A variety of tablet formulations have been approved for sale, e.g., compressed conventional instant tablets release (IR) containing 25 mg, 50 mg, 100 mg, 150 mg, or 200 mg of the active ingredient. They are given once, twice or three times a day. When lamotrigine is added to an anti-epileptic drug regimen containing valproic acid, titration begins with 25 mg every other day for weeks 1 and 2 and increases to 25 mg daily for weeks 3 and 4. After this initial period, the maintenance dose of 100 to 400 mg / day can be achieved by increasing the dose by 25 to 50 mg / day. If lamotrigine is added to enzyme-inducing antiepileptic drugs (EIAEDS) without valproic acid, the dose is 50 mg / day for 1 and 2 weeks followed by 100 mg / day in two divided doses. To achieve a maintenance dose of 300 to 500 mg / day in two divided doses, the doses may be increased by 100 mg / day every 1 to 2 weeks. These regimes deliver a therapeutic amount of lamotrigine.

In addition, WO 92/13527 (The Wellcome Foundation Limited) describes tablet formulations comprising water dispersible tablets containing lamotrigine and a dispersant, the dispersant being a swellable clay such as smectite and essentially present in tablet granules to provide a tablet which is dispersible in water in 3 minutes, providing a dispersion which passes through a 710 µm sieve. The tablet may optionally be film-coated. In this case, the dispersion time is less than 5 minutes. The dispersible chewable tablets, which can be swallowed whole, chewed or dispersed in a small amount of water, are sold in dosages containing the active ingredient in amounts of 2 mg, 5 mg, 25 mg, or 100 mg. These pills are mainly given to children. WO96 / 17611 (The Wellcome Foundation Limited) discloses pharmaceutical compositions containing:

a) 0.5 to 50% by weight of lamotrigine;

b) from 15 to 50% by weight of lactose

c) from 15 to 50% by weight of starch;

d) from 0.5 to 50% of crystalline cellulose; and

e) from 5 to 15% by weight of polyvinylpyrrolidone;

and which are in the form of a free flowing powder with the following characteristics:

(i) without granules with a particle size greater than 850 μm, (ii) at least 90% by weight of a particle size of 75 to 850 μm, (iii) the granules disintegrate within 30 minutes according to the Japanese Pharmacopoeia Disintegration Test, 12th edition and (iv ) at least 90% by weight of lamotrigine is dissolved in 30 minutes when the granules are subjected to the Dissolution Test, method 2 (paddle method) of the Japanese Pharmacopoeia 12th edition 1991.

After oral administration, lamotrigine is rapidly and completely absorbed with negligible first pass metabolism. Full bioavailability is approximately 98%, which is unaffected by food.

The dispersible chewable tablets have been found to be equivalent to lamotrigine IR compressed tablets in terms of rate and degree of absorption, whether administered dispersed in water, chewed and swallowed, or swallowed whole.

Other drugs for the treatment of epilepsy are, but are not limited to, carbamazepine (TEGRETOLTM), valproate (DepakoteTM), tiagabine (GabitrilTM), levetiracetam, (KeppraTM), gabapentin (NeurontinTM) and phenytoin (DilantinTM) . Carbamazepine is available as an immediate release tablet, a sustained release chewable tablet (Carbatrol; sustained release beads) or a Tegretol-XR osmotic pump type tablet and an oral liquid. Valproate is available as an immediate release tablet and suspension. In the US, valproate is also available as Depakote, a delayed release tablet (coated) that contains sodium valproate + valproate 1: 1 in a formulation, and Depakote ER, a formulation

PL 213 565 B1 for sustained release. Gabapentin, tiagabine, and levetiracetam are available as immediate-release tablets. Dylanthin is available in "sealed, modifying capsules."

Existing commercial lamotrigine tablet formulations provide an immediate release of the active ingredients when the tablets reach the stomach. The peak in plasma concentrations appears from 1.4 to

4.8 hours after drug administration. The disadvantage is that the plasma concentration (pharmacokinetic (PK) profile) achieved by conventional tablets is cyclical with peaks appearing after administration followed by troughs appearing before the next drug administration, see Figure (1).

It is assumed that especially in the treatment of epilepsy, these minima may lead to a seizure turning point and that the peak plasma concentration may cause some adverse events (AEs) to occur in some patients or alternatively the rate of increase in the plasma concentration in the initial stages before the concentration peak is reached plasma, may also affect the AE profile.

Only recently has it been known where lamotrigine is absorbed in the gastrointestinal tract. By examining the absorption region, it has recently been found that the extent of absorption of lamotrigine is constant when drug is delivered to any point in the gastrointestinal tract between the stomach and the ascending colon. Also, the degree of absorption is the same whether the drug is provided as a solid or as a solution.

WO 98/47491 discloses controlled release formulations in which at least one active ingredient is incorporated into a homogeneous matrix containing amounts of two smart polymers with opposite wettability characteristics, one of which has a strong hydrophobic tendency and the other a strong hydrophilic tendency. The combination of polymers is used in the range of 1:50 to 50: 1 of an amount effective to control the release of the pharmaceutically active substance.

WO 9714415 discloses sustained release compositions consisting of a core and a coating which release the NMDA antagonist only in the intestine. In contrast, the formulation of the present invention includes one or more openings in the coating extending from the outside of the coating through substantially the entire coating to the core, which allow some of the lamotrigine to be released already in the stomach.

The present invention relates to a sustained release formulation comprising:

1) a core containing lamotrigine or a pharmaceutically acceptable derivative thereof;

2) an outer sheath covering said core, the thickness of which is adjusted such that it is substantially impermeable to fluid present in the patient's gastrointestinal tract and substantially impermeable to lamotrigine or a pharmaceutically acceptable derivative thereof found in the core, and

3) the coating has one or more openings extending from the outside of the coating substantially through the coating but not extending into the core to allow the release of lamotrigine or a pharmaceutically acceptable derivative thereof from the core into the fluid present in the patient's gastrointestinal tract, the openings being surface or contiguous area, from about 10 to 60 percent of the outer surface of the formulation, and released lamotrigine or a pharmaceutically acceptable derivative thereof passes substantially through the opening and wherein the outer coating dissolves when the surrounding pH exceeds 5.

Preferably, the formulation comprises a core further comprising a release retarding excipient. The formulation preferably comprises a core containing

a) 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof;

b) 17.5 to 70% by weight of the release retarding polymer;

c) 0 to 60% by weight of a diluent;

d) 0 to 20% by weight of compression aid i

e) 0.1 to 2.5% by weight of a lubricant and an outer coating containing

f) 0.05mm to 0.30mm of polymer.

Preferably in this formulation the release retarding excipient or release retarding polymer is an HPMC polymer.

Preferably, the outer coating in this formulation comprises a methacrylic acid copolymer.

Preferably, the formulation, when administered to a human, produces an AUC in the range of 80 to 125% and a C max about 30% lower than an instant release tablet containing the same amount of lamotrigine or a pharmaceutically acceptable derivative thereof.

PL 213 565 B1

CNS disorders can be treated by administering lamotrigine. It is preferred to orally administer to the patient a therapeutically effective amount of lamotrigine or a pharmaceutically acceptable derivative thereof in the form of a sustained release formulation wherein the lamotrigine or a pharmaceutically acceptable derivative is released about 2 to 20 hours after administration, preferably 6 to 16 hours after administration, and more preferably 10 hours after administration. up to 15 hours, alternatively 10 to 14 hours after administration.

The term "CNS disorders" as used herein includes epilepsy, pain, edema, multiple sclerosis, schizophrenia, and psychiatric conditions including bipolar disorders, especially epilepsy, pain, edema, and psychiatric conditions including bipolar disorders, particularly epilepsy, pain and bipolar disorders.

The term "pain as used herein includes acute pain such as musculoskeletal pain, post-operative pain, and surgical pain, chronic pain such as chronic inflammatory pain (e.g., rheumatoid arthritis and osteoarthritis), neuropathic pain (e.g., post-herpetic neuralgia, trigeminal neuralgia, sympathetic pain and diabetic neuropathy pain) and pain associated with cancer and fibro-fibroids or pain associated with migraine.

Schizophrenia is a serious psychiatric disease that affects 1% of the world's population. The onset of this disorder typically appears in late teens or early 20s and becomes a lifelong condition in about 80% of cases. Additionally, schizophrenia is associated with significant mortality, with 40% of patients attempting suicide within 10 years of onset of the disorder. The disorder is rated as the 5th leading cause of disability in the US according to a joint World Health Organization-World Bank study in 1996 (Murray and Lopez, 1996).

Clinical presentations of schizophrenia can include positive symptoms such as hallucinations, delusions, or disturbed thinking, and negative symptoms such as apathy, avolition, or speech poverty.

Treatment of schizophrenia is based on the use of anti-dopaminergic drugs following the original discovery in the 1950s of the efficacy and mechanism of action of chlorpromazine. Chlorpromazine and the so-called "typical anti-psychotic drugs are still widely used today, although due to their association with motor side effects, they are increasingly being replaced by newer" atypical antipsychotics such as clozapine (Clozaril) ™) olanzapine (Zyprexa TM) or risperidone (Risperdal ™). These newer drugs have a mixed pharmacology that includes antagonism at the dopaminergic D2 receptor and antagonism at the 5-HT2a receptor. Despite the efficacy and relative safety of these newer drugs, a significant percentage of patients do not respond to treatment and many do not achieve clinically significant improvements in global functioning and quality of life.

In some patients, episodes of major depression, mania or mixed mania may occur in addition to symptoms of schizophrenia. The difference between schizophrenia and mood disorder is blurred, and the diagnosis of schizoaffective disorder is often used. Typically, treatment of a schizo-effective disorder requires a combination of an antipsychotic, an antidepressant, a mood stabilizer, and anxiolytics. While positive psychotic symptoms can usually be controlled, negative symptoms and affective symptoms are poorly treated with current medications.

Despite 40 years of development, there remains a significant unmet need for treating patients with chronic, debilitating schizophrenia.

Multiple sclerosis (MS) is an autoimmune, progressive disease of the central nervous system (CNS) in which the myelin plaques (the protective layer that covers the nerve fibers) in the brain and spinal cord are destroyed by the body's own immune system. This destruction leads to scarring and damage to vital nerve fibers and can manifest itself in a wide variety of symptoms depending on the parts of the brain and spinal cord that are affected. Spinal cord injuries can cause tingling or numbness as well as a feeling of heaviness and / or weakness in the limbs. Brain damage can cause muscle weakness, weariness, unsteady gait, numbness, slurred speech, blurred vision, dizziness, and the like. Leandri et al. (J. Neurol (2000 247: 556-558) reported that lamotrigine has been used in the treatment of trigeminal neuralgia secondary to multiple sclerosis.

Lamotrigine or a pharmaceutically acceptable derivative thereof can be administered in the treatment of multiple sclerosis.

The term "pharmaceutically acceptable derivative" as used herein means a salt, ester or salt of such ester which, when administered to a recipient, such as a human, is capable of delivering (directly or indirectly) lamotrigine or an active metabolite thereof. Preferred salts are inorganic acid salts such as hydrochlorides, hydrobromides, phosphates, or organic acid salts such as acetate fumarate, xinophoanate, tartrate, succinate or glutarate.

The term "treatment as used herein includes the treatment of an established disorder and also includes its prophylaxis. This is especially true for epilepsy, where the drug can treat an attack or prevent future attacks.

The term "sustained release" as used herein refers to the gradual but steady release of lamotrigine over any sustained period after oral administration e.g. for 2-20 hours, preferably between 6 and 16 hours, and more preferably between 10 and 15 hours, alternatively 10 and 14 hours, and it starts when the formulation reaches the stomach and begins to disintegrate / dissolve / erode. Release will continue over time and may continue in the small intestine and after the preparation has reached the large intestine.

In CNS disorders, a therapeutically effective amount of lamotrigine may be administered to the patient as a sustained release formulation with substantially all of the lamotrigine released from the formulation within 2 to 20 hours after administration, preferably 6 to 16 hours after administration, and more preferably 10 to 15, alternatively 10 to 14 hours after administration.

As used herein, the term "substantially all" means greater than 85%, preferably greater than 90%.

Administration of lamotrigine over this time period delivers it progressively to sites where it is readily absorbed, but with a slower increase in serum concentrations and reduced sub-dose peaks to minimize dose-related adverse events (AEs) while still providing sufficient trough plasma levels to maintain efficacy. serum (Cmin). A formulation that achieves the AUC equivalent to conventional immediate / immediate release (IR) tablets (90% confidence interval (Cl) of the geometric least squares (GLS) ratio means that the ratio should be fall in the range of 80-125% compared to the reference IR product) is called "bioequivalent."

Alternatively, a sustained-release formulation would not be recognized by the Food and Drug Administration (FDA) as a bioequivalent of IR tablets unless the evaluation criterion and the associated 90% confidence interval for Cmax are within 80-125% of an IR product with an AUC remaining within the range 80-125% compared to the reference IR product.

Basically, the preparations are designed such that the release of the active substance takes place mainly in the stomach, small intestine and colon.

Lamotrigine or a pharmaceutically acceptable derivative thereof can be administered in the form of a sustained release formulation wherein lamotrigine or a pharmaceutically acceptable derivative thereof is in the range of 1 to 500 mg, preferably 25 to 400 mg.

Preferably, the sustained release formulation is administered at a dosage regimen that is sufficient to maintain control of the disorder.

The preferred dosing schedule is one dose per day.

The advantage of sustained release formulations is increased patient compliance.

Socio-economic factors do not affect patient cooperation: lack of cooperation occurs both in rich, well-educated and healthy patients and in patients outside these categories. In most cases, epilepsy is a lifelong disease that requires consistent and adequate levels of an anti-epileptic drug (AED) in the blood to maximize seizure control. Moreover, it is usually believed that any additional attack may increase the risk of a recurrence and worsen the overall prognosis. Therefore, the goal of the initial treatment of patients with epilepsy is to maintain adequate levels of AEDs and prevent further attacks. Adherence to prescribed dosing regimens is essential to maintaining therapeutic blood levels.

Epilepsy patients are often treated with multiple medications. Patients with severe or persistent epilepsy often require the simultaneous administration of two or more AEDs to achieve adequate seizure control. It is also not uncommon for a patient to have other concomitant chronic conditions, such as depression, heart conditions or diabetes, also requiring adherence to the daily dosing regimen.

Currently, it is recommended to treat bipolar disorders with a single daily dose, but the present formulation provides a lower increase in the plasma concentration of the drug and, therefore, is expected to provide the patient with a beneficial effect.

PL 213 565 B1

A significant advantage in the treatment of pain would be the availability of a tablet to be taken once daily. Pain is a permanent medical condition, therefore a sustained-release formulation would provide pain relief by delivering a Cmax at the appropriate point of the day or night depending on when the patient's pain is most debilitating.

Preferably, the formulation provides about 10 to 40%, alternatively 10 to 20%, of a reduction in Cmax relative to the Cmax obtained in the same patient after an IR dose when administered once daily.

Preferably, the time to reach C max (t max) post-dose of the formulation is 8 to 24 hours, alternatively 10 to 16 hours post-dose.

Preferably, the formulation provides a growth rate to t max less than 50% of an individual IR dose.

The formulation can provide 24 hours post-dose mean serum trough concentration (Cmin) of at least 80 to 125% compared to the same IR dose in the same patient, or (Cmin) higher than the IR dose and / or beyond the range of 80 to 125 % compared with the same IR dose.

Preferably, the t fluctuation index (Cmax-Cmin / Cave) for the formulation is in the range of 0.15 to 0.45.

Currently, some patients experience adverse events (AE) from the CNS such as dizziness, ataxia (ataxia (ataxia), diplopia and rash after administration of the classic IR tablet.

With an IR formulation, the AE levels are, for example, 31 to 38% dizziness, 10 to 22% ataxia, and 24 to 28% double vision. Without wishing to be bound by theory, the applicant believes that some of these adverse events are related to the peak in plasma levels or the rate of increase in plasma concentration after administration and before the peak plasma concentration is reached.

The risk of rash and severe rash may be related to the initial dose or the rate of increase in the dose of lamotrigine, and development of a formulation that lowers the peak level during titration may reduce the risk of these adverse symptoms.

Preferably, the reduction of the AE profile is a reduction in the rate of an undesirable event of at least one side effect selected from dizziness, ataxia, diplopia or rash.

Preferably, the reduction of the AE profile is a reduction in the undesirable event rate of at least one side effect by 10%, preferably 20%, more preferably 30%.

The dose in a sustained release formulation intended to be swallowed whole, where the integrity of the dosage form is essential to controlling the rate of release, may conventionally be provided as a number of swallow tablets or capsules, for example two, three or four. In the event that release occurs from a number of discrete particles, beads, or granules, the dosage form need not be ingested intact as long as the beads or particles themselves are intact.

The dose in a sustained release formulation may also be provided as a single tablet.

Preferably, the sustained release formulation of the present invention has an in vitro dissolution profile where 40 to 65% preferably 45 to 65%, more preferably 45 to 55% of the lamotrigine content is dissolved within 3 to 8 hours, more preferably 4 to 6 hours. and 90% of the lamotrigine is dissolved within 6 to 16 hours, preferably 4 to 6 hours and alternatively 10 to 14 hours. In comparison, a conventional immediate release lamotrigine tablet dissolves 80% within 30 minutes. Dissolution profile can be measured by standard dissolution assay e.g. <724> Dissolution Test Apparatus 1 or 2 or 3 or 4 provided in USP 24 2000 as updated in subsequent supplements, at 37.0 ± 0.5 ° C, using dilute hydrochloric acid or other a suitable medium (500-3000 ml) and a rotation speed of 50-100 rpm.

The sustained release formulation can provide an in vivo "Area Under the Concentration Curve (AUC)" value that is equivalent to that of existing immediate release IR tablets, for example at least 80%, preferably at least 90% to 110%, more preferably about 100%. %, but not more than 125% of the value of the corresponding dose of lamotrigine taken as conventional (immediate release) formulation during the same dosing period. thereby maximizing the absorption of lamotrigine from the sustained release formulation.

The pharmacological profile for the dosage of the formulation of the present invention can be readily determined in a single dose bioavailability study in human volunteers. Plasma lamotrigine concentrations can be readily determined from blood samples obtained from patients according to procedures well known and documented in the art.

PL 213 565 B1

It is known that a therapeutically effective amount will depend on the age of the patient, body weight, severity of the disease, and other medications.

Preferably the sustained release formulations are functional coated tablets or caplets or time release tablets or caplet matrices containing wax or polymer or osmotic pump system type formulations or a combination thereof. They can also be beads, granules, controlled release steroids that are contained in a capsule or administered from sachets or other powder dosage unit devices.

Representative sustained-release formulations include a tablet, including swallow tablets, a capsule, granules, or a sachet, typically a swallow tablet, which may be coated or uncoated.

A formulation of the invention containing lamotrigine or a pharmaceutically acceptable derivative thereof may contain a release-retarding excipient that allows for the sustained release of lamotrigine or a pharmaceutically acceptable derivative thereof. Suitable release retarding excipients include release retarding polymers that may or may not swell on contact with water or an aqueous medium such as stomach contents; polymeric materials that form a gel on contact with water or an aqueous medium; polymeric materials which have both swelling and gelling properties when in contact with water or an aqueous medium, and pH-sensitive polymers, e.g. polymers based on methacrylic acid copolymers such as Eudragit (trademark) e.g. Eudragit L, polymers that can be used alone or with a plasticizer.

These sustained release formulations are often referred to in the art as "matrix formulations when a drug is incorporated into a hydrated polymer matrix system and released by diffusion or erosion, for example in WO 98/47491 and US 5242627.

Retarder polymers that may or may not swell, include, but are not limited to, cross-linked sodium carboxymethyl cellulose, cross-linked hydroxy propyl cellulose, hydroxyethyl cellulose, high molecular weight hydroxypropyl methyl cellulose, carboxymethyl amide, polymethyl methacrylate polyvinyl acetylacrylate, polyvinyl methyl acrylate copolymer high molecular weight etc.

The gelling retarding release polymers include methyl cellulose, carboxymethyl cellulose, low molecular weight hydroxypropyl methylcellulose, hydroxyethyl cellulose, low molecular weight polyvinyl alcohols, polyoxyethylene glycols, uncrosslinked polyvinylpyrrolidone gum etc.

Release retarding polymers having swelling and gelling properties include medium viscosity hydroxypropyl methylcellulose and medium viscosity polyvinyl alcohols.

Preferably the release retarding polymer used has a molecular weight in the range 5 to 95 thousand, more preferably in the range 10 to 50 thousand.

Preferably, the release retarding polymer is one of the available grades of hydroxypropylmethyl cellulose or hydroxyethyl cellulose.

Examples of polymers that can be used include Methocel K4M (trademark), Methocel E5M (trademark), Methocel E50 (trademark), MethocelE4M (trademark), Methocel E100M (trademark), MethocelK15M (trademark), MethocelK100M ( trademark), MethocelK100LV (trademark), Methocel K4M (trademark), POLYOX WSR N-80 or mixtures thereof. Alternatively, examples of polymers that can be used include Methocel K4M (trademark), Methocel E5 (trademark), Methocel E50 (trademark), Methocel E4M (trademark), Methocel K15M (trademark), Methocel K100LV (trademark) ), POLYOX WSR N-80 or their mixtures.

Other known release retarding polymers that can be incorporated include hydrocolloids such as natural or synthetic gums, cellulose derivatives other than those listed above, carbohydrate based substances such as acacia, tragacanth, carob gum, guar gum, agar, pectin, carrageenan , soluble and insoluble alginates, carboxypolymethylene, casein, zein and the like, and protein substances such as gelatin.

Preferably the release retarding polymer is Methocel E4M Grade, POLYOX WSR N-80, Methocel K100LV.

The sustained release formulation may also include diluent (s) and compression aids such as lactose, microcrystalline cellulose, dicalcium phosphate, sucrose, mannitol, xylitol, starches, and lubricants such as magnesium stearate, sodium stearyl fumarate.

PL 213 565 B1 and stearic acid. The sustained release formulation may further contain disintegrants such as cross-linked polyvinylpyrrolidone (CLPVP) and sodium starch glycolate; binders such as povidone (polyvinylpyrrolidone), flow aids such as silicon dioxide or talc. Typically the sustained release formulation contains from about 2.5 to 80% by weight of lamotrigine; from 0 to 70% by weight of a diluent / compression aid and from 0.1 to 2.5% by weight of a lubricant. Preferably, the release retarding excipient is a release retarding polymer.

Preferably, the release retarding polymer is present in an amount ranging from 10 to 70% by weight.

Preferably the sustained release formulation comprises 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof.

Preferably, the sustained release formulation comprises

a) 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof

b) 10 to 70% by weight of the release retarding polymer;

c) 0 to 70% by weight of a diluent;

d) 0 to 20% by weight of a compression aid;

e) 0.1 to 2.5% by weight of a lubricant.

In a preferred embodiment, the sustained release formulation comprises

a) 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof;

b) 17.5 to 70% by weight of the release retarding polymer;

c) 0 to 60% by weight of a diluent;

d) 0 to 20% by weight of compression aid i

e) 0.1 to 2.5% by weight of a lubricant.

A sustained release formulation that does not contain an ironing aid is also preferred.

The formulation may contain a system comprising lamotrigine or a pharmaceutically acceptable derivative thereof and a release retarding coating on one or more of the exterior surfaces of the system, for example tablets or beads. A conventional compressed immediate release tablet may be at least partially covered by a release retarding coating, or alternatively a pharmaceutically acceptable bead is used in which lamotrigine is incorporated and the bead is then at least partially coated with a release retarding coating. The use of beads allows flexibility in the dosing schedule as the dose can be measured to suit the needs of the patient.

The release retarding coating can be a film coat that can be compressed or spray-dried and can act as a semi-permeable barrier, thus allowing diffusion control of drug release through the water-insoluble or partially water-soluble polymer. Alternatively, the membrane shell may regulate the rate of dissolution. Such a membrane shell may, for example, consist of polymers which are either substantially or completely impermeable to water or aqueous media or are slowly erodable in water or aqueous media or biological fluids and / or which swell on contact with water or aqueous media or biological fluids. A suitable membrane coating should retain these properties at least until complete or substantially complete transfer of the active material content into the surrounding medium. The coated tablets are referred to as functional coated tablets.

Suitable polymers for the film coat include acrylates, methacrylates, copolymers of acrylic acid or esters thereof, celluloses and derivatives thereof, such as ethyl celluloses, cellulose acetate propionate, polyethylenes and polyvinyl alcohol, etc. Film coatings include polymers that may swell upon contact with water or aqueous media swell to such an extent that the swollen layer forms a relatively large swollen mass the size of which delays its immediate discharge from the stomach into the intestine. The membrane shell may itself contain lamotrigine, for example, the shell may be a slow release or delayed release layer. Membrane shells can typically have an individual thickness of 2 to 10 µm.

Polymers suitable for film coating polymers that are relatively impermeable to water include hydroxypropylmethylcellulose polymers, for example, Methocel (trademark), the series of polymers mentioned above, for example the polymers Methocel K100M, Methocel K15M, Eudragit (trademark), Aquacoat (trademark) trademark) and are used singly or in combination or possibly combined with the polymer Ethocel (trademark). Alternatively, and more preferably, the membrane shell may be compressed. A preferred polymer is SURELEASE (trademark)

An aqueous dispersion of ethyl cellulose (E-7-19010). It is available from COLORCON, a division of Berwind Pharmaceutical Services Inc. Additionally, a mixture of SURELEASE polymer or other suitable partially permeable polymer and blowing material may be used, for example OPADRY (trade mark) pure (YS-2-7013), which is also obtainable from COLORCON. The range that can be used is 3 to 5% by weight of the coating on the tablet.

Additional embodiments have 50% to 80% by weight of the SURELEASE polymer film coating and 50% to 20% by weight of the OPADRY film coating.

A plasticizer such as hydrogenated castor oil may be associated with the polymer. Conventional binders, fillers, lubricants, dyes such as iron oxides or organic dyes and ironing aids etc. may also be included in the coating. such as Polyvidon K30 (trademark), magnesium stearate and silicon dioxide e.g. Syloid 244 (trademark).

In a sustained release formulation for lamotrigine or a pharmaceutically acceptable derivative thereof, which has two release phases of lamotrigine or a pharmaceutically acceptable derivative thereof, the release rate in the first phase differs from the release rate in the second phase. Preferably the release rate in the first phase will be less than the release rate in the second phase. Most preferably, less than 15% release of lamotrigine or a pharmaceutically acceptable derivative thereof occurs in the esophagus and stomach in the first phase, and the release rate of lamotrigine or a pharmaceutically acceptable derivative thereof in the second phase is faster than in the first phase.

For example, the first phase would be an average of 0 to 2 hours and the second phase would be 2 to 20 hours, preferably 2 to 16 hours, preferably 2 to 15 hours. It is known that the timing of gastric and intestinal residence times may be different for each patient, and therefore 2 hours is the average time in the patient population.

Preferably, the release of lamotrigine or a pharmaceutically acceptable derivative thereof in the first phase is less than 10%.

This aspect of the invention is particularly advantageous as it reduces the release of lamotrigine in the stomach where the solubility of lamotrigine is higher (compared to the lower sections of the gastrointestinal tract). This may produce a substantially linear increase in plasma concentrations of lamotrigine in vivo.

Sustained release systems are described in US Patent 5,004,614 and are referred to as "DiffCORE ™ systems."

Preferably, the core further comprises a release-retarding excipient in the formulation according to the invention.

More preferably the release retarding excipients are as described above for the matrix formulations.

Moreover, the outer coating may dissolve within 0.3 to 5 hours after administration or when the surrounding pH exceeds 5, preferably 5.5.

More preferably, the core contains a release retarding excipient and the outer coating dissolves from 0.3 to 5 hours after administration, or when the surrounding pH exceeds preferably 5.5.

Preferably, such formulations consist of a matrix core as described above and an outer shell in which there are one or more holes.

Preferably the release retarding excipient is as described above for the matrix formulation.

Preferably, the thickness of the outer coating ranges from 0.05mm to 0.30mm, preferably 0.10mm to 0.20mm.

Preferably, the outer cover comprises one or two holes.

Preferably the outer coating is selected from the group consisting of ethylcellulose, acrylate polymers, polyamides, polymethacrylates, waxes, polyanhydrides, polyglycolides, polylactides, polybutyrate, polyvalerate, polycaprolactones, natural oils, polydimethylsilidylcellulide, non-cross-sodium carboxymethylcellulide, non-cross-sodium carboxymethylcellulide, non-crossover cellulose ethers, cellulose acetate phthalates, polyvinyl alcohol phthalates, shellac, zein, hydroxypropyl methylcellulose phthalate, methacrylic acid polymers or copolymers, one or more of the above, and the like.

Preferably the formulation comprises 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof.

PL 213 565 B1

In a preferred embodiment, the sustained release formulation comprises a core comprising:

a) 2.5 to 80% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof;

b) 17.5 to 70% by weight of the release retarding polymer;

c) 0 to 60% by weight of a diluent;

d) 0 to 20% by weight of a compression aid; and

e) 0.1 to 2.5% by weight of a lubricant and an outer coating containing

f) 0.05mm to 0.30mm of polymer.

In a preferred embodiment of the sustained release formulation, a compression aid is not present.

In a preferred embodiment, the sustained release formulation comprises a core containing

a) 5 to 66% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof;

b) 17.5 to 66.3% by weight of the release retarding polymer;

c) 0 to 60% by weight of a diluent i

d) 0.1 to 0.4 wt.% of a lubricant and an outer coating containing

e) 0.05mm to 0.30mm of polymer.

Preferably the release retarding polymer is an HPMC polymer, more preferably it is selected from Methocel E4M, Grade CR, POLYOX WSRN-80 or Methocel K100LV or mixtures thereof.

Preferably the polymer of the outer layer is a methacrylic acid copolymer, preferably Eudragit.

Preferably, lamotrigine or a pharmaceutically acceptable derivative thereof is in an amount of 5 to 55%.

More preferably, the sustained release formulation comprises a core containing:

a) 5 to 55% by weight of lamotrigine or a pharmaceutically acceptable derivative thereof;

b) 17.5 to 66.3% by weight of Methocel E4MP, CR class, POLYOX WSRN-80 or Methocel

K100LV or mixtures thereof;

c) 25 to 60 wt.% lactose i

d) 0.1 to 0.4% by weight of magnesium stearate and an outer coating containing d) 0.05 mm to 0.30 mm of Eudragit L30.

Environmental fluid means a fluid that exhibits or mimics the dissolving properties of such fluid that is present in the gastrointestinal tract of a subject.

"The dosing period is the time from administration to the end of the release of lamotrigine or a pharmaceutically acceptable derivative thereof, e.g. 0 to 20 hours, preferably 0 to 16 hours, more preferably 0 to 15, alternatively 0 to 14 hours."

As used herein, the term "substantially impermeable" means that the lamotrigine or a pharmaceutically acceptable derivative thereof may have little or no passage through the coating, e.g. in an amount of less than 5%, preferably less than 2%, more preferably even less than 1%.

When the term "aperture" is used herein, this means a slit in the outer coating, e.g., an opening in the outer coating of the tablet, and includes a portion of the surface of the outer layer which is, for example, significantly thinner than the rest of the layer.

When the term "release is used herein, it means the exit of lamotrigine or a pharmaceutically acceptable derivative thereof from the formulation into the environmental fluid, for example, by dissolution, diffusion, osmosis, or erosion."

Matrix tablets, as described above, may be compressed or spray-coated with an aqueous polymer solution to form a coating. Coating may occur with any standard coating apparatus known to one skilled in the art, for example a Vector ™ apparatus. A hole or holes in the tablet coating is then drilled through. The holes can be produced by removing some (some) part of the film coating from the surface of the previously coated tablets.

Typically the area removed is 0.1% to 50%, preferably about 15 to 20%. The holes may be produced by mechanical drilling, ultrasonic or laser cutting, preferably mechanical drilling.

The openings may be of any shape, for example oval, round, square or even text shaped, for example a company logo, preferably the opening is round.

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The size of the opening will depend on the size of the tablet, but for example for a 9-10 mm tablet it may be 0.1 to 6-7 mm, preferably 4-4.5 mm.

If the tablet has more than one hole, the holes may be on the same or a different surface of the tablet, preferably on opposite surfaces.

The opening may be centered on the surface of the tablet or off center.

The tablets can be round, oval, elliptical, discoid or capsule-shaped, flat or deep convex. Preferably the tablets are round or oval in shape with a standard convexity.

Preparations of the osmotic pump type containing lamotrigine and an osmotic agent are known. The active ingredient "is pumped out of the tablet through a hole in the water-permeable membrane. Examples of preparations of the osmotic pump type for other drugs are included in WO95 / 29665.

Systems exist for the sustained release of lamotrigine or a pharmaceutically acceptable derivative thereof including a "deposit-core" containing an effective amount of the active ingredient and having a defined geometric form, and b) a support platform. support-platform) used for said deposit core, wherein "the deposit core comprises at least an active ingredient and at least one component selected from the group consisting of (1) a polymeric material that swells upon contact with water or aqueous liquids and a gelling material polymer material in which the ratio of the swellable polymeric material to the gelling polymeric material is in the range of 1: 9 to 9: 1, and (2) a single polymeric material having both gelling and swelling properties, the support platform being a flexible support applied to the deposit core so that it partially covers the surface of the "deposit core and changes with changes due to the hydration of the deposit core and slowly dissolves" and / or gels slowly in aqueous liquids.

Such systems can be described as "Precise technology. The support platform may include polymers such as hydroxypropyl methylcellulose, plasticizers such as glycerin, binders such as polyvinylpyrrolidone, hydrophilic agents such as lactose and silica, and / or hydrophobic agents such as magnesium stearate and glycerides. The polymer (s) typically make up 30 to 90% by weight of the supporting platform, e.g. about 35 to 40%. Plasticizers may constitute at least 2% by weight of the supporting platform, for example 15 to 20%. The binder (s), hydrophilic agent (s) and hydrophobic agent (s) together typically constitute up to about 50% by weight of the supporting platform, for example about 40 to 50%.

Tablet formulations exemplified by the sustained release formulation of the invention may contain a wax or similar water-insoluble material to form the matrix. Such tablets can be made by dry milling the drug and any dilution materials with the particulate wax material. Examples of suitable wax materials are cetyl alcohol, stearyl alcohol, palmitoyl alcohol, oleyl alcohol and carnuba wax. The resulting blend is then compressed into tablets using conventional tablet making techniques. An alternative method of making these tablets would be to granulate the drug with diluting materials and a suitable volatile granulating fluid (water, ethanol, isopropanol) and dry the granules, then coat them with a molten wax material. The resulting granules are then compressed into tablets using conventional tablet manufacturing techniques.

Granule-based tablets may be made by spraying a solution or suspension of one of the methacrylate-based release controlling agents (Eudragit - trademark), a mixture of the drug mixed with one of the common diluents. Examples of suitable Eudragits are NE30D, L, S. The pellets produced by the process are then dried and pressed using conventional tablet technology.

The tablet formulations of the present invention may be fully or partially coated with a coating, which may be a protective layer to prevent ingress of moisture or damage to the tablet. The protective layer may itself contain the active ingredient and may, for example, be an immediate release layer which disintegrates immediately on contact with water or aqueous media. Preferred materials for the protective layer are hydroxypropyl methylcellulose and polyethylene glycol with titanium dioxide as an opacifying agent, for example as described in WO 95/28927 (SmithKline Beecham).

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The protective layer, if present, may typically be prepared by wet granulation or dry granulation techniques such as using a roller compactor. Typically the backing material e.g. Methocel (trade mark) is suspended in a solvent such as ethanol containing granulating acid such as Ethocel or Polyvidon K-30 (trade mark) followed by mixing, sieving and granulation. The first layer can be produced, then a barrier layer can be deposited thereon e.g. by pressing, spraying or dipping, then a second layer is formed such that the barrier layer is sandwiched between the first and second layers to form a sandwich arrangement. Additionally or alternatively, first and second layers may be formed, and then the barrier layer may be formed, for example, by compression, spraying, or dipping at one or more surface ends of the tablet.

Chewable tablets typically contain a chewable base made of, for example, mannitol alone, sorbitol, dextrose, fructose, lactose, xylolithol, maltitol, sucrose or galactose, or in combination. The chewable tablets may also contain further adjuvants, for example, disintegrating agents, lubricants, sweetening agents, coloring agents and flavoring agents. Such further excipients together will preferably comprise from 3 to 10%, more preferably 4 to 8%, even more preferably 4 to 7% by weight of the tablet. Disintegrants may be present in an amount of 1 to 4%, preferably 1 to 3%, more preferably 1 to 2% by weight of the tablet. Representative disintegrants include crospovidone, sodium starch glycolate, starches such as corn starch and rice starch, croscarmellose sodium, cellulose products such as microcrystalline cellulose, finely divided cellulose, low-substituted hydroxypropyl cellulose, used alone or in admixture. The preferred disintegrant is crospovidone. Lubricants may be present in an amount of from 0.25 to 2.0%, preferably from 0.5 to 1.2% by weight of the tablet. Preferred lubricants include magnesium stearate. Preferably the sweetening agent is an artificial sweetener such as sodium saccharin or aspartame, preferably aspartame, which may be present in an amount from 0.5 to 1.5% by weight of the tablet. Preferably the tablet is substantially sugar (sucrose) free. Preferably the flavors include fruit flavors, which may be natural or synthetic, for example, peppermint, cherry, and banana, or a mixture thereof.

Single dose sachets contain in addition to the drug excipients conventionally contained in a sachet formulation such as a sweetening agent, for example aspartame, flavoring agents, for example fruit flavors, optionally a suspending agent such as xanthan gum, also silica gel, which acts as a drying agent.

The capsules of the present invention contain, in addition to the drug substance, excipients typically contained in the capsule, for example starch, lactose, microcrystalline cellulose, ethyl cellulose, magnesium stearate. Preferably capsules are made of materials such as HPMC or a gelatin / PEG combination. Preferably the capsules will contain beads or granules. These beads or granules consist of the drug substance in a concentration between 5 and 95%, preferably 20 to 80%, more preferably 50 to 80%. The drug substance is mixed with a suitable granulating agent such as microcrystalline cellulose, lactose and granulated using a suitable granulating fluid such as water, ethanol and / or isopropanol. The wet granules are pushed through small holes 0.5 mm to 3 mm in diameter, then spheronized into discrete particles using a high-speed wheel. The spherical particles are then dried and coated with a release-controlling film coating containing, for example, ethyl cellulose, pH sensitive or insensitive methacrylic acid copolymers, and derivatives thereof. The coated particles are filled into capsule shells.

Preferably, the unit dosage forms of the present invention are packaged in containers that inhibit the ingress of atmospheric moisture, for example, blisters, tightly sealed bottles or drainage bags etc. which are commonly used in the art. Preferred bottles include HDPE bottles.

Other sustained release formulations that may be suitable for incorporating lamotrigine or another suitable derivative thereof are described in:

Sustained Release Medications, Chemical Technology reviev No. 177, Ed JC Johnson, Noyes Data Corporation 1980.

Controlled Drug Delivery, Fundamentals and Applications, 2 ed Eds. JR Robinson, VHL Lee. Mercel Dekkes Inc. New York 1987.

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Examples of delayed release formulations which are suitable for incorporating lamotrigine or other suitable derivatives thereof are described in Remington's Pharmaceutical Science 16th Edition, Mack Publishing Company 1890, Ed.

Donkey.

The invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1. Simulated pharmacokinetic profile of lamotrigine for 200 mg lamotrigine IR tablets administered twice daily.

Figure 2. Dissolution profile of three different lots of 150 mg lamotrigine IR tablets.

Figure 3. Dissolution profiles for the matrix tablet of example 1.

Figure 4. Dissolution profiles for the matrix tablet of example 2.

Figure 5. Dissolution profiles for the coated tablet of example 3. Figure 5 shows the dissolution profiles for tablets coated with coating solution B of up to 3% and 5% weight gain. Both dissolve on average over 90% after 3 hours.

Figure 6. Lamotrigine dissolution profiles for DiffCORE 25 mg and 200 mg tablets from Example 4.

Figure 7. Mean serum PK profiles over 0-36 hours for the various 25 mg and 200 mg matrix tablets of Example 2.

Another sustained release formulation of lamotrigine or a pharmaceutically acceptable derivative thereof of the present invention has an in vitro dissolution profile substantially similar to that shown in Figures 3, 4 or 5.

Example 1-Matrix formulations

Example 1a) Matrix tablets with 35% polymer (The polymers are either Methocel E4MP CR, Methocel K100 LV or Polyox WSR N-80)

<td>Ingredient</td><td>Quantity (mg / tablet)</td><td>Amount (wt%)</td>

<td>Lamotrgin</td><td> 150</td><td> 30,0</td>

<td>Lactose (Fast-Flow)</td><td> 35</td><td> 7,0</td>

<td>Microcrystalline cellulose</td><td> 138</td><td> 27,6</td>

<td>Polymer</td><td> 175</td><td> 35,0</td>

<td>Magnesium stearate</td><td> 2</td><td> 0,4</td>

<td>Total weight of the tablet</td><td> 500</td><td> 100</td>

Mass production method

First, the ingredients from the containers were weighed in the following amounts:

Ingredients Quantity (g)

Lamotrigine 450.0

Lactose (Fast-Flo) 105.0

Microcrystalline cellulose 414.0

Polymer 525.0

Magnesium stearate 6.0

The ingredients were then screened using Russell-SIV equipment with a 20 mesh screen (850 µm) or an equivalent mesh size and stored in a stainless steel mixing vessel.

Lamotrigine, lactose, microcrystalline cellulose, and polymer were mixed for 15 minutes using a suitable mixer such as a Matcon-Buls bin mixer, V-mixer, or equivalent. Magnesium stearate was added to the mixture and mixing was continued for approximately 2 minutes.

The lubricant blend was then compressed using an appropriate rotary tablet press, typically a Fette 2090 or equivalent. In the process, during the tabletting process, the tablet weight and hardness were periodically controlled and, if necessary, the parameters of the tablet press were adjusted.

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Example 1b) Matrix tablets with 25% polymer (The polymers are either Methocel E4MP CR, Methocel K100 LV or Polyox WSR N-80)

<td>Ingredient</td><td>Quantity (mg / tablet)</td><td>Amount (wt%)</td>

<td>Lamotrigine</td><td> 150</td><td> 30,0</td>

<td>Lactose (Fast-Flow)</td><td> 85</td><td> 17,0</td>

<td>Microcrystalline cellulose</td><td> 138</td><td> 27,6</td>

<td>Polymer</td><td> 125</td><td> 25,0</td>

<td>Magnesium stearate</td><td> 2</td><td> 0,4</td>

<td>Total weight of the tablet</td><td> 500</td><td> 100</td>

Mass production method

First, the ingredients from the containers were weighed in the following amounts:

Ingredients Quantity (g)

Lamotrigine 450.0

Lactose (Fast-Flo) 255.0

Microcrystalline cellulose 414.0

Polymer 375.0

Magnesium stearate 6.0

The ingredients were then screened using Russell-SIV equipment with a 20 mesh (850 µm) screen or an equivalent mesh size screen and stored in a stainless steel mixing container.

Lamotrigine, lactose, microcrystalline cellulose, and polymer were mixed for 15 minutes using a suitable mixer such as a Matcon-Buls bin mixer, V-mixer, or equivalent. Magnesium stearate was added to the mixture and mixing was continued for approximately 2 minutes.

The lubricant blend was then compressed using an appropriate rotary tablet press, typically a Fette 2090 or equivalent. In the process, the tablet weight and hardness were periodically controlled and, if necessary, the parameters of the tablet press were adjusted.

Example 1c) Matrix tablets with 15% polymer (The polymers are either Methocel E4MP CR, Methocel K100LV or Polyox WSR N-80)

<td>Ingredient</td><td>Quantity (mg / tablet)</td><td>Amount (wt%)</td>

<td>Lamotrigine</td><td> 150</td><td> 30,0</td>

<td>Lactose (Fast-Flow)</td><td> 35</td><td> 7,0</td>

<td>Microcrystalline cellulose</td><td> 238</td><td> 47,6</td>

<td>Polymer</td><td> 75</td><td> 15,0</td>

<td>Magnesium stearate</td><td> 2</td><td> 0,4</td>

<td>Total weight of the tablet</td><td> 500</td><td> 100</td>

Mass production method

First, the ingredients from the containers are weighed in the following amounts:

Ingredients Quantity (g)

Lamotrigine 450.0

Lactose (Fast-Flo) 105.0

Microcrystalline cellulose 714.0

Polymer 225.0

Magnesium stearate 6.0

The ingredients were then screened using Russell-SIV equipment with a 20 mesh (850 µm) screen or an equivalent mesh size screen and stored in a stainless steel mixing container.

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Lamotrigine, lactose, microcrystalline cellulose, and polymer were mixed for 15 minutes using a suitable mixer such as a Matcon-Buls bin mixer, V-mixer, or equivalent. Magnesium stearate was added to the mixture and mixing was continued for approximately 2 minutes.

The lubricant blend was then compressed using an appropriate rotary tablet press, typically a Fette 2090 or equivalent. In the process, the tablet weight and hardness were periodically controlled and, if necessary, the parameters of the tablet press were adjusted.

Example 2a) Matrix formulations

<td>Power</td><td colspan="2">25 mg</td><td colspan="2">50 mg</td><td colspan="2">100 mg</td><td colspan="2">200 mg</td>

<td>Earnings</td><td>slow</td><td>fast</td><td>slow</td><td>fast</td><td>slow</td><td>fast</td><td>slow</td><td>fast</td>

<td>lamotrigine</td><td>25 mg (12.5%)</td><td>25 mg (12.5%)</td><td>50 mg (25%)</td><td>50 mg (25%)</td><td>100 mg (33.3%)</td><td>100 mg (33.3%)</td><td>200 mg (50%)</td><td>200 mg (50%)</td>

<td>E4M</td><td> 55,75</td><td> 20%</td><td> 30%</td><td> 10%</td><td> 25%</td><td> 25%</td><td> 15%</td><td> 15%</td>

<td>K100LV</td><td> 9,75</td><td> 20%</td><td> 20%</td><td> 25%</td><td> 10%</td><td> 25%</td><td> 5%</td><td> 15%</td>

<td>lactose</td><td>qs</td><td>qs</td><td>qs</td><td>qs</td><td>qs</td><td>qs</td><td>qs</td><td>qs</td>

<td>Magnesium stearate</td><td> 0,4%</td><td> 0,4%</td><td> 0,4%</td><td> 0,4%</td><td> 0,4%</td><td> 0,4%</td><td> 0,40%</td><td> 0,4%</td>

<td>Tablet weight (mg)</td><td> 300</td><td> 300</td><td> 325</td><td> 325</td><td> 350</td><td> 350</td><td> 400</td><td> 400</td>

qs = the amount needed to reach the target tablet weight

In the table above, "slow means tablets where 90% of the lamotrigine is dissolved within 16 hours," fast means tablets where 90% of the lamotrigine is dissolved within 6 hours.

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<img file="PL213565B1_D0001.tif" />

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<img file="PL213565B1_D0002.tif" />

The formulations described in Example 2 were prepared as shown in the flow chart below.

Example 3: Coated formulation

<td>Ingredient</td><td>Quantity (mg / tablet)</td><td>Amount (% wt / wt)</td>

<td>Lamotrigine</td><td> 150</td><td> 30,0</td>

<td>Microcrystalline cellulose</td><td> 345</td><td> 69,0</td>

<td>Magnesium stearate</td><td> 5</td><td> 1,0</td>

<td>Total weight of the tablet</td><td> 500</td><td> 100</td>

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Mass production method

First, the ingredients from the containers are weighed in the following amounts:

Ingredients Quantity (kg)

Lamotrigine 4.5

Microcrystalline cellulose 10.35

Magnesium stearate 0.15

The ingredients are screened using Russell-SIV equipment with a 12 mesh screen (850 µm) or an equivalent mesh size screen and stored in a stainless steel mixing container.

Lamotrigine and microcrystalline cellulose are mixed for 15 minutes using a suitable mixer such as a Matcon-Buls bin mixer, V-mixer, or equivalent. Magnesium stearate is added to the mixture and mixing is continued for approximately 2 minutes.

The lubricant blend is compressed using a rotary tablet press, typically a Fette 2090 or equivalent. In the process of controlling tablet weight and hardness, appropriate intervals are used throughout the course of the compression process and, if necessary, the parameters of the tablet press are adjusted.

The tablets are coated using an O'Hara LabCoat II, or an equivalent coating machine. The tablets are sprayed with a 50/50 (solution A) or 80/20 (solution B) solution of Surelase and Opadry. The aqueous coating solutions A and B are described below. The tablets are coated to a 5% increase in theoretical weight.

Coating solution A

162.5 grams of Surelease (E7-19060) and 162.5 grams of Opadra (YS-2-7013) were weighed and placed in a stainless steel mixing tank. 2437.5 grams of water was added. Stirred until homogeneous. Continuously agitated during application.

Coating solution B

260.00 grams of Surelease (E7-19060) and 65.00 grams of Opadry (YS-2-7013) were weighed and placed in a stainless steel mixing tank. 1061.67 grams of water was added. Continuously agitated during application.

Example 4: DiffCORE tablets

DiffCore Tablet Preparation Details, 25mg

<td rowspan="2">Ingredients</td><td>Quantity (mg / tablet)¹</td><td></td>

<td>Fast</td><td>Slow</td>

<td colspan="3">Core</td>

<td>Lamotrigine</td><td> 25</td><td> 25</td>

<td>Hydroxypropyl methylcellulose (HPMC), K100LV, Prem CR USP / EP</td><td> 37,8</td><td> 53,55</td>

<td>Hydroxypropyl methylcellulose (HPMC), E4M, Prem CR, USP</td><td> 52,2</td><td> 73,95</td>

<td>200 mesh lactose monohydrate NF</td><td> 183,8</td><td> 146,31</td>

<td>Purified Water, EP / USP</td><td></td><td></td>

<td>Magnesium stearate, EP / NF</td><td> 1,2</td><td> 1,2</td>

<td colspan="3">Outer cover</td>

<td>Eudragit L30 D-55 (30 wt.% Solution)</td><td> 13,08</td><td> 12,98</td>

<td>Iron Oxide Red, USP</td><td> 0,15</td><td> 0,278</td>

<td>Triethyl citrate, NF</td><td> 1,37</td><td> 1,36</td>

<td>Glycerol Monostearate, NF</td><td> 0,37</td><td> 0,37</td>

<td>Polysorbate 80, NF</td><td> 0,016</td><td> 0,016</td>

<td>Purified Water EP / USP</td><td></td><td></td>

"Fast means 12 hours release period," slow means 15 hours release period. Example of a DiffiCORE tablet formulation, 200 mg

<td rowspan="2">Ingredients</td><td>Quantity (mg / tablet)¹</td>

<td>Slow</td>

<td colspan="2">Core</td>

<td>Lamotrigine</td><td> 200</td>

<td>Hydroxypropyl methylcellulose (HPMC), E4M, K100LV, Prem CR USP / EP</td><td> 62,64</td>

<td>Hydroxypropyl methylcellulose (HPMC), E4M Prem CR, USP</td><td> 45,36</td>

<td>Lactose Monohydrate, 200 mesh NF</td><td> 90,4</td>

<td>Purified Water, EP / USP</td><td></td>

<td>Magnesium stearate, EP / NF</td><td> 1,6</td>

<td colspan="2">Outer cover</td>

<td>Eudragit L30D-55 (30% w / w solution)</td><td> 17,3</td>

<td>Iron Oxide Red, USP</td><td> 0,37</td>

<td>Triethyl citrate, NF</td><td> 1,81</td>

<td>Glycerol Monostearate NF</td><td> 0,494</td>

<td>Polysorbate 80, NF</td><td> 0,02</td>

<td>Purified Water EP / USP</td><td></td>

A tablet core was prepared as described in Example 2 and then coated.

Coating

The tablets were coated using a standard coating machine e.g. a Vector ™ machine purchased from Vector or equivalent. The tablets were sprayed with a 10% aqueous solution of Eudragit as described below. The tablets were coated to a 5% increase in theoretical weight.

Example of the preparation of a 10% coating solution

Part A.

350 ml of 30% Eudragit L30 D55 solution was diluted with 150 ml of water. 11 g of triethyl citrate was added and the solution was mixed thoroughly.

Hello B

440 g of purified water was added to a separate vessel and heated to about 60 ° C.

Using an appropriate (high shear) mixer, 0.13 g of Polysorbate 80 NF and 3.0 g of glycerol monostearate were introduced into the solution of Kalish. 4.0 g of iron oxide was added and homogenized for 15 minutes at high speed.

Part A and part B were combined and the final weight was adjusted to 1000 g with purified water and mixed.

Drilling

The tablets were mechanically drilled using a standard drill press. The tablet was placed in the tablet holder and drilled carefully until the coating was removed from the drilled surface, then the tablet was inverted and then the opposite side was drilled.

Finally, the drilled tablets were examined for weight loss (hole depth), hole edge quality and overall appearance.

Example 5

Human Pharmacokinetic Study of Lamotrigine Prolonged Release:

The in vivo degradation of the prolonged-release lamotrigine formulation was assessed in a pharmacokinetic study in healthy volunteers. The study was an incomplete block diagram consisting of two doses (e.g., 25 mg (Pellet Strength 1) and 200 mg (Pellet Strength 2) and 3 different rates of sustained release at each dose with IR formulation as a reference.

Participation in the intake of 4 out of 7 possible types / preparations. For each formulation, blood samples were collected from each volunteer for a specified time to measure serum concentrations of lamotrigine, and consequently the pharmacokinetic parameters of lamotrigine were determined. The safety and tolerability of each formulation were assessed.

Example 6.

Pharmacokinetic study of the sustained release formulation of lamotrigine in humans The formulations as described in Example 2 were tested in a human volunteer study as described in Example 5. 25 mg and 200 mg of the slow, medium and fast formulation were dosed to human volunteers to give mean 0-36 hour profiles. PK as shown in Figure 5.

The different release rates from the tablets described in Example 2 resulted in different PK profiles. The AUC values ​​for the various rates were compared to the IR tablets, with the C max reduced to approximately 30%.

A further aspect of the invention is a pharmaceutical formulation as described in any one of Examples 1 to 4.

<td>trade name</td><td>Generic description</td><td>Supplier</td>

<td>Methocel E4M</td><td>28-30% hydroxypropyl methylcellulose substituted with 28-30% methoxy and 8.5% hydroxypropyl, having a nominal viscosity of 4,000 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel K15M</td><td>22% methoxy and 8.1% hydroxypropyl substituted hydroxypropyl methylcellulose, having a nominal viscosity of 15,000 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel K100M</td><td>22% methoxy and 8.1% hydroxypropyl methylcellulose and hydroxypropyl having a nominal viscosity of 1,000,000 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel K4M</td><td>22% methoxy and 8.1% hydroxypropyl substituted hydroxypropyl methylcellulose, having a nominal viscosity of 4,000 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel E5</td><td>29% methoxy and 8.5% hydroxypropyl substituted hydroxypropyl methylcellulose having a nominal viscosity 5 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel E5M</td><td>29% methoxy and 8.5% hydroxypropyl substituted hydroxypropyl methylcellulose, having a nominal viscosity of 5,000 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel E50</td><td>29% methoxy and 8.5% hydroxypropyl substituted hydroxypropyl methylcellulose having a nominal viscosity 50 mPas (2% solution in water)</td><td>Dow</td>

<td>Methocel K100LV</td><td>Low viscosity hydroxypropyl methylcellulose</td><td>Dow</td>

<td>POLYOX^TmWSRN-80</td><td>High molecular weight poly (ethylene oxide) polymer. Molecular weight 200,000, nominal viscosity 55-90 cPas. s (5% solution)</td><td>Dow</td>

<td>Opadry</td><td>Water dispersion</td><td>Colorcon</td>

<td>(YS-2-7013)</td><td>hydroxymethylpropylcellulose</td><td></td>

<td>Surelease (E-7-19010)</td><td>Aqueous ethyl cellulose dispersion</td><td>Colocron</td>

<td>Eudragit® L30D-55 Eudragit® RS 30D Eudragit® RL 30D</td><td>Methacrylic acid, ethyl acrylate copolymer Ammonium methacrylate copolymer RS = 5% ammonium groups RL = 10% ammonium groups</td><td>Rohm Pharma ROHM Pharma</td>

<td>Aquacoat</td><td>Ethylcellulose latex suspension</td><td>(FMC)</td>

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