Needleless syringe and the use thereof

The invention relates to a needle-free syringe and its use in treatments with therapeutic agent, for the administration of slow acting drugs or for the administration of genetic material in living skin cells, for the purpose of long-term gene therapy.

From the patent application WO-A-92/04439, there is known an apparatus used for the genetic transformation of plant cells, which comprises an elongated tubular device, a pressurizable gas reservoir, connected at one end of the device, means between the ends the device, intended to support or introduce the particles to be propelled and a membrane that opens the passage through the tubular device, until it is broken, due to the application of a predetermined pressure to the gas in the tank, after which the particles are driven from the tubular device by the gas stream.

As specified in the aforementioned patent application, the particles may initially be immobilized, for example electrostatically, on or upstream of a fractured diaphragm, which is broken when the gas flow begins and which may be the same fractured membrane whose rupture initiates the flow of gas.

Alternatively, the particles may be injected into the gas stream through a lumen needle.

The disadvantage of this device and its use, respectively, is that it does not allow the administration of medicines in controlled doses, as well as the fact that it is not portable by itself.

The technical problem, which is solved by the present invention, consists in the constructive construction of a needle-free syringe, allowing to maintain the components of a drug in a solid state, without coming into contact with each other and penetrating into controlled quantities and depths thereof. drugs, which are otherwise unstable in the form of a wet mixture.

The needle-free syringe, according to the invention, consists of a reservoir located inside an elongated body fixed by a cylindrical portion, within which drive means slides, to ensure a gaseous pressure on the upstream side of a fractured membrane, which initially closes the passage. to an elongated tubular nozzle, sufficient pressure to break the membrane and cause a supersonic flow of gas in which the particles of therapeutic agent are entrained through the tubular nozzle, It eliminates the disadvantages of known solutions by the fact that the therapeutic agent particles are located between the fractured membrane and a fractured diaphragm, both extending transversely inside the tubular nozzle.

The therapeutic agent particles are initially contained in a sealed capsule, which is opened by the gas released from the reservoir, thus allowing the therapeutic agent particles to enter.

The tubular nozzle has a converging upper portion, in the downstream direction of the flow of therapeutic agent particles, connected by a neck with a divergent portion.

The use of the needle-free syringe according to the invention for the administration of the particles instead of the transdermal administration takes place at a speed between 200 and 2500 m / s, the particles having a size between 10 and 250 pm and a density between 0.1 and 25 g / cm³.

The needle-free syringe according to the invention has the advantage that it reduces the risk of spreading contagious and autoimmune diseases, which are commonly transmitted by other means, for example by re-use of the syringe needles.

The administration of medicines by liquid jet causes skin damage and bleeding and does not offer any advantage over syringe needles in preventing the spread of blood-borne diseases.

Thus, the main advantages of the invention are the lack of use of the needles and the less painful procedure, the disappearance of the risk of infection, the administration of medicines in solid, natural form, the faster and safer use compared with the administration of liquid medicines, using needle syringes, the lack of sharp parts. .

RO 118569 Β1

Preliminary experiments confirm the theoretical model and prove the efficacy of the new techno-50, especially for transdermal injection of sprayed drugs.

The theoretical model assumes that the skin behaves like water as a resistant medium. Thus, at low values ​​of the Reynolds number, the forward resistance respects the Stokes law, but at high values ​​of the Reynolds number, the forward resistance coefficient is constant. Evidence, regarding this behavior of the resistance to advancement on a 55 sphere with a smooth surface in a uniform environment such as water, is given in Fluid Mechanics by BS Massey.

The calculations show that proper penetration, for example between 100 and 500 µm under the skin, is possible, using particles of drug sprayed with insufficient size to harm the skin cells, with gas velocities of 1 ... 8 Mach, preferably, 1 ... 3 Mach, 60 which are relatively easy to obtain by forcing a fractured membrane.

Penetration depends on the size of the particles, ie the nominal diameter of the particles, assuming that they are spherical, density and kinetic viscosity of the skin.

Depending on the tissue, different penetration distances will be required, for example epidermis or muscle, the parameters that determine the penetration being chosen so that the treatment is optimal.

A feature of the invention is that the depth of penetration can be controlled tightly, being possible the specific administration of a certain location.

Thus, for example, the penetration depth can be chosen less than 1 mm for an intradermal active agent, 1 ... 2 mm for a subcutaneous active agent and 10 mm or more for an active agent when administered intramuscularly.

The agent itself will be chosen, as the case may be, for example, as agents such as viruses or immunization proteins, analgesics such as ibuprofen, hormones such as somatotropic, medicines such as insulin or calcitonin.

The agent can be administered without carrier, diluent or density increase factor. In certain situations, for example, to provide particles of a certain size containing a highly active drug, a carrier may also be present, but its amount will usually be much smaller than in a conventional pharmaceutical composition, e.g. less than 75% and usually less than 50% of the particle volume

Thus, as a first example, insulin particles with a nominal diameter 80 of 10 µm, with an initial velocity of 750 m / s, were injected into the skin. Assuming that the insulin particles have a relative density close to that of the skin, ie about 1, and the kinetic viscosity of the skin is approximately equal to that of the water 10 ... 6 m²/ s, the penetration depth, at which the particles stop in the skin, is about 200 µm. In order to obtain a greater penetration, the particle size can be increased to 20 pm and the initial velocity to 1500m / s, 85 in which case, the penetration depth increases to about 480 pm.

In a second example of needle-free syringe use, this time for the genetic transformation of cells, for example, the injection into the corn cells of DNA-coated tungsten particles, comparable penetration into the tissue would require a reduction in particle size, to increase their density. Thus, in the case of coated particles 90 having a nominal diameter of 1 µm and a density of about 20, injected into maize cells with an initial velocity of 500 m / s, the penetration is about 200 µm.

In general, the new injection technique may use particles preferably between 0.1 and 250 µm, for transdermal injection of sprayed drugs between 1 and 50 µm, preferably between 10 and 20 µm. The particles will have a density between 0.1 and 95 25 g / cm³, but for transdermal injection, preferably between 0.5 and 2 g / cm³, the most advantageous 1 g / cm³.

RO 118569 Β1

Injection rates can be between 200 and 2500 m / s, even up to 3000 m / s, or more, but for transdermal injection of sprayed drugs, preferably between 500 and 1500 m / s, the most advantageous between 750 and 1000 m / s.

The sprayed therapeutic agent will be ground and screened to obtain a precise diameter value. Alternatively, the particles may be small spheres up to 100 µm in diameter, in which solid or liquid drugs are encapsulated. If the sphere has a controlled permeability, this may be an additional means of obtaining a slow release of the drug after administration. In order to ensure the particle size and mass required for proper penetration, in particular, if the therapeutic agent is strong or low density, an inert carrier should be included. It can be mixed with the therapeutic agent or provide the material for the spheres. The required dose will depend on the quantity and concentration of the therapeutic agent and on the number of particles mobilized at a time.

A different approach, regarding the operating parameters of the new method of using the needle-free syringe, consists in selecting the initial particle size and velocity, to obtain a pulse density equal to the particle impulse divided on its front surface, with values between 2 and 10 kg / s / m, preferably between 4 and 7 kg / s / m. The impulse density control is desirable to be performed, in order to obtain a controlled administration, depending on the tissue.

In the first mentioned example, in which the sprayed insulin particles have 110 µm, being designed with a speed of 750 m / s, the pulse density is 5 kg / s / m.

In the second example, regarding the injection of tungsten carrier particles into maize cells, the particle diameter being 1 µm and having a velocity of 500 m / s, the pulse density is 6.7 kg / s / m.

In terms of syringe construction, the energy means may comprise a chamber upstream of the membrane, preferably in the syringe handle and means for raising the gas pressure in the chamber, which may contain a pressurized gas source connected to the chamber by a resistant coupling. and a drain valve. Alternatively, the syringe is portable and self contained, incorporating its own compressed gas tank, which can be refilled. The usual operating parameters for a system are a rupture pressure of the diaphragms between 20 and 75 at, in a pressure chamber with a volume between 1 and 5 ml, generating a supersonic shock wave with speeds between 1 and 8 Mach.

The velocity of the gas / particles leaving the nozzle and therefore the penetration depth depends on the breaking pressure of the membrane, but in fact surprising in the case of such a rapid phenomenon, experiments have shown that the velocity depends critically on the geometry of the nozzle.

The advantage is that the penetration depth can be controlled more quickly by changing the size of the nozzle than by the thickness of the membrane. The nozzle preferably has a convergent upstream portion followed by a neck with a cylindrical or preferably divergent portion. The upstream portion allows the pressurized agent to enter through a wider area, and the supersonic shock is produced in the neck area. The divergence of the downstream portion of the nozzle significantly affects the velocity of the expanded gas in a pseudo-stable state, with supersonic speeds. Increasing the velocity of the pseudo-stable state increases the depth of penetration of the particles, which is surprising for a phenomenon considered to be predominantly ephemeral.

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The divergent portion seems to transform the flow pattern of the passenger following the rupture of the membrane, in a smooth exit from the nozzle, uniformizing the particle flow to the target. In addition, the nozzle divergence causes an equal spread of the particles on the target.

In a series of experiments, with helium upstream of the membrane and varying only the breaking pressure of the membrane, penetration into a uniform target was measured. Breaking pressures of 42, 61 and 100 at produced penetration of 38.5 and 70 units. On the other hand, similar experiments, in which only the internal geometry of the divergent portion of the nozzle was modified, also produced different penetrations.

RO 118569 Β1

Thus, three nozzles with the same length and diameter of output, but different internal geometries, chosen to produce speeds of 1.2 and 3 Mach, under the theoretical conditions of stable state, produced penetration depths of 15, 21 and 34 units. 150

The type of gas used for propulsion is not decisive at first glance, relatively inexpensive gases such as helium, nitrogen and carbon dioxide being considered adequate. However, the gas applied on the upstream side of the membrane, in order to break it, must be sterile, contributing to the flow of gas carried by the particles through the nozzle to the patient's skin or other target, for this purpose helium is available in inert form, sterile. 155

It has been appreciated that there is still an advantage in using helium for breaking the membrane. Most of the particles move to the contact surface between the upstream and downstream gases, initially separated by the membrane, the contact surface closely following the shock wave. It seems that the easier the gas applied to the upstream face of the membrane, the higher the velocity of the shock wave through the nozzle, for a given pressure difference, of 160 parts, and of the other, of the membrane at the moment of rupture. and for an established nozzle geometry. It turns out that if a lighter gas is used, the speed required for the shock wave can be reached at a lower pressure difference, provided that the membrane breaks at that pressure difference. In general, the gas applied on the upstream side of the membrane, in order to break it, is lighter than air. 165

This appreciation led to the idea that the speed of the shock wave through the nozzle is the higher the gas in the nozzle is easier. It has been suggested to use at least a partial vacuum, but this is difficult to obtain and maintain in practice.

To reduce the breaking pressure of the membrane, necessary to obtain the required speed of the shock wave, and of the contact surface, in the nozzle, the interior of the nozzle downstream of 170 membranes contains a gas, such as helium, which is easier than air at atmospheric pressure, the gas being easily retained by an easily removable insulation, for example a plug or lid, or a detachable foil, at the bottom end of the nozzle.

When used, the insulation is removed immediately before, so that the light gas will not have enough time to diffuse out of the nozzle before injection. 175

The insulation of the downstream end of the nozzle also has the advantage of ensuring sterility, so that there is a minimal chance that a foreign body will enter the nozzle, for example, after a sterile package is opened and before injection, so that foreign bodies can inevitably be entrained by the flow. of carrier gases of drug particles into the patient's skin.

The source of the particles should contain a precise dose of the drug and can be handled in sterile form. In fact, absolute sterility is being pursued, so it is assumed that at least the tubular nozzle assembly and the residues of the particle source and of the fractured membrane, even of the pressurizable chamber, can be replaced by a new assembly from a sealed sterile package.

It is possible that the entire device, including the pressurizing mechanism, the pressurizing chamber, the nozzle, the membrane and the particles, is disposable, the remnants of the device being then discarded. This device should be manufactured at the lowest possible price, in particular, from plastic. There is the alternative of separating the syringe into two parts: a downstream, disposable part, containing at least the sterile nozzle, membrane and particles, and an upstream part, comprising at least part of the energy means. However, in this particular embodiment, the pressurized gas source and the coupling to the pressurization chamber would not be single-use, being relatively expensive metal parts.

Because the lower end and the exposed lower surfaces of these parts will communicate with the inside of the pressurization chamber and during the administration of the drug with the inside of the tubular nozzle, there is a danger of bacterial or other contamination of the stable parts of the syringe.

RO 118569 Β1

Therefore, the downstream end of the chamber is preferably closed with a sterile barrier, for example, a semipermeable membrane, which allows the passage of gas, but not of bacteria. Alternatively, the chamber may be cylindrical and the sterile barrier is a piston, there being means for advancing the piston into the cylindrical chamber to compress the gas from within. The piston advancement means can be provided by a pressure gas source applied to the upstream end of the piston. In this case, the syringe can be portable and stand-alone, containing its own compressed gas tank and a valve that can be manually opened to expose the gas pressure piston. Alternatively, the piston advance means may comprise a compressed spring and then manually released to determine the piston advance.

The use of the piston ensures the initial existence of a predetermined volume of gas at a predetermined pressure, which can be increased by the movement of the piston inside the cylindrical chamber, however slow, until the pressure in the chamber is sufficient to break the membrane and propel the particles.

The amount of gas flowing through the tubular device is therefore precisely determined and produces a little annoying noise. The volume of cylinder required to travel, to increase the gas pressure to, for example between 20 and 40 bar, sufficient to break the membrane, may be reduced if helium or other gas in the cylindrical chamber is pre-pressurized to an atmospheric pressure, for example 2 bar, before the piston advance.

Also, to avoid dead space between the end of the piston and the membrane, when it deforms before breaking, the end of the piston is preferably convex, so that it can be closer to the center of the membrane.

If the needle-free syringe is to be used in the clinic for drug administration, it is assumed that the assembly consisting of the tubular nozzle, membrane, particles, cylindrical chamber, pressurizing means and piston will be supplied in a sealed sterile package and will be discarded after use. .

In the alternative embodiment of the combination between the single-use and the fixed parts, contamination from the piston actuating means, be they a spring, a manually operated plunger or a source of pressurized fluid behind the piston, will be avoided, as the piston maintains During administration of the drug an insulating barrier between the fixed parts upstream of the piston and the interior of the disposable parts downstream of the piston.

The single-use assembly will be manufactured at a lower price, in particular, from plastic. Because during the administration in the cylindrical chamber a high pressure is born, tending to deform the cylindrical chamber wall outwards, with the danger of gas backlash behind the piston, the cylindrical chamber wall will be made of a rigid plastic material. Alternatively, and cheaper, the cylindrical chamber can be inserted at the time of use in a rigid housing, with a tight fit, this housing does not need to be disposable.

Another use of the new needle-free syringe is in the laboratory to introduce genetic material into living cells for genetic transformation. To this end, assuming that the laboratory has sterile conditions, the single-use parts need not necessarily be pre-assembled sterile, and it may be sufficient for the syringe to be assembled in the laboratory, for example from components including a separate tubular nozzle and cylindrical chamber, which are separable to allow the replacement of a broken membrane, and a separate piston to be inserted into the cylindrical chamber after dosing the genetic material on the membrane.

The various modes of particle positioning prior to membrane rupture, presented in WO 92/04439, are convenient when the particles are made of a very dense metal and / or for the genetic transformation of plant cells, in which case, the number of particles, which reach the target, it is not of major importance. However, this type of device is not convenient for spray medicines, because the drug's particulate matter is so light that it is difficult to immobilize before propulsion, and must be provided at the prescribed dose and kept sterile prior to administration.

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250 For this purpose, the sprayed therapeutic agent particles are preferably positioned between two fractured diaphragms, extending transversely into the interior of the nozzle.

One or both of the diaphragms can even form the main fractured membrane, the rupture of which initiates the flow of gas. The unit may alternatively be located upstream or downstream of the main fracturing membrane, at any convenient position along the nozzle.

The membrane and diaphragm or diaphragms may be permanent fixed elements in a single-use syringe or a single-use part of the needle-free syringe, or may be attached to the circumference between the connectable parts of the nozzle, for example between the threaded sections together.

Preferably, the edges of the diaphragms are sealed together directly on the circumference, to form a capsule or bag containing the particles, or indirectly for example, by gluing on the opposite axial faces of an intermediate ring. In either case, the edges of the sealed unit may be squeezed between separate portions of the nozzle.

The capsule, bag or any other type of sealed unit may include three or more diaphragms forming isolated compartments containing different therapeutic agents to be injected together. This is an advantage for administering drug mixtures that might otherwise react unfavorably, even in the dry state.

The unit can be operated as a sterile assembly and contains a precise dose of the drug. By arranging its rupture, when the membrane breaks, the administration of the drug in the dose and at the necessary time is ensured.

A particular advantage of the new technique for injecting dried sprayed drugs is that it can be used to administer a stable mixture of drugs, which is unstable in the case of wet mixing.

The sealed unit contains a predetermined dose of the drug and it is very important that the entire dose is administered to the patient's skin. It is therefore important that none of the particles remain stuck between the diaphragms in the vicinity of their edges after breaking.

For this reason, at least one of the diaphragms is preferably waved in the opposite direction to the others, to achieve a sufficient separation to locate most of the particles radially inward relative to the edges of the diaphragms.

It can be seen that the penetration depth of the particles increases as the nozzle is closer to the patient's skin. This is true when the distance is reduced to a few tens of millimeters, the experiments showing that there is an optimal distance for maximum penetration, which is rapidly reduced in the case of a closer approach of the skin nozzle, probably due to the reflected shock wave that interferes with mating surface.

It may be preferable to have a spacer element at the downstream end of the nozzle, which can provide a distance from the patient's skin up to 35 mm, preferably between 5 and 15 mm.

Another reason to ensure this spacing between the nozzle and the patient's skin is to allow the jet leaving the nozzle to extend radially outward and consequently the particles will penetrate into the patient's skin on a surface much larger than the area of ​​the nozzle cross-section. For example, if the nozzle has at its downstream end an opening of approximately 2.5 mm in diameter, the divergence of the jet would cause a uniform spread over an area of ​​20 ... 30 mm in diameter of the patient's skin. Accordingly, it is preferable that the spacer member be a tubular shell sufficiently wide and of a shape that it does not prevent the jet of drug-containing particles, driven by gas, leaving the nozzle, to extend over a cross section of at least five or, preferably ten times larger than the surface of the nozzle outlet orifice, at the downstream end of the tubular sheath, ie at the level of the tubular sheath contact with the patient's skin.

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RO 118569 Β1

The spacer may be associated with a noise absorber or noise mitigating medium, such as cotton. A perforated spacer would provide a sound damping effect. Preferably, the tubular shell constituting the spacer is not perforated, and a sound damper is positioned in an annular space, inside a cylinder surrounding the nozzle, to receive the shock wave reflected by the patient's skin through the spacer.

The sound damper may have a labyrinthine construction, providing, for example, a winding path between the ring extensions, extending radially outward from the surface of the nozzle, interspersed with those extending radially inward from the cylinder, the path leading to at least an exit to the outside through the cylinder wall.

This arrangement has been shown to be very effective in reducing the loud noise created by breaking the diaphragm and leaving the nozzle by the shock wave that carries the particles in contact with the patient's skin.

The following example illustrates the usefulness of a needle-free syringe according to the invention.

Eight healthy male guinea pigs were anesthetized with 0.25 ml Sagatal injections (sodium pentatol barbiton, 60 mg / ml). The fur from the peritoneal region of each one was removed, using a commercially available epilating cream. In animals 1 ... 4, 0.1 mg bovine insulin (Sigma spray form) was injected using a needle-free syringe. In animals 5 and 6, 1 mg of bovine insulin (sprayed form) was injected under identical conditions. The average insulin particle size was 10 pm and the delivery rate was 750 m / s. For comparison, in animals 7 and 8, 0.1 mg insulin dissolved in 0.9 NaCl solution was injected using a conventional needle syringe.

Blood samples were taken from each animal before injection and then four hours after injection. In each case, 3 drops of blood (approximately 50 μΙ) were taken from the tail of the animal and mixed with 2 μΙ heparin, to prevent coagulation. This mixture was in turn mixed with 100 μΙ of 6% perchloric acid to stop glucose metabolism. The mixture was centrifuged and blood glucose supernatant was analyzed.

Blood glucose level (NGS) for animals 1 ... 6 is shown in the following table.

NGS (millimoles)

<td>Animal</td><td>0 hours</td><td>4 hours</td>

<td> 1</td><td> 5,30</td><td> 2,22</td>

<td> 2</td><td> 5,40</td><td> 1,29</td>

<td> 3</td><td> 7,22</td><td> 1,51</td>

<td> 4</td><td> 5,64</td><td> 2,87</td>

<td> 5</td><td> 5,07</td><td> 0,91</td>

<td> 6</td><td> 5,36</td><td> 2,63</td>

The results of animals 7 and 8 showed NGS of 2.2 ... 3.3 mM and 2 ... 2.4 mM, after 1 and 2 hours respectively. From these results, it appears that insulin was administered by injection without needle , in sufficient quantities, to produce a significant therapeutic effect, and the level of this therapeutic effect is comparable to that resulting from conventional injection using the needle syringe.

Comparison of the results at 4 h with other results shows that reducing working pressure (from 65 to 40 bar) and reducing the useful insulin dose (from 1 to 0.1 mg) does not produce significant differences in NGS.

RO 118569 Β1

This conclusion is very important for three reasons:

- the reduction of the working pressure also reduces the mechanical resistance conditions of the possible clinical devices for mass production;

- reducing the working pressure ensures the elimination of adverse effects on the skin;

- reducing the dose of the drug demonstrates the high efficiency of this method, ensuring sufficient bioavailability associated with this method of administration.

Following are some examples of making the needle-free syringe, according to the invention, in connection with FIGS. 1 ... 8, which represents:

- Fig. 1, axial section through the needle-free syringe, according to the first embodiment;

FIG. 2 is a view of the needle-free syringe;

- Fig. 3, "exploded" view of the needle-free syringe, from fig. 1;

- Figs. 4,5 and 6, sections similar to that of Figs. 1, representing other embodiments of the needle-free syringe;

- fig.7, section after the path vll-vll, from fig.6;

- Fig. 8, axial section through a capsule used in the needle-free syringes shown.

The needle-free syringe according to the invention, represented in Figs. 1 ... 3, is approximately 18 cm long and is intended to be held in the hand, with the cops over the upper end.

The needle-free syringe comprises a cylindrical body 10 containing a reservoir 11. The upper end of the cylindrical body 10 is closed by a lid 12, provided with a sleeve 13, and the lower end of the cylindrical body 10 is closed by the wall 14, extended by a sleeve 15 threaded to the outside.

The plunger 16 shows the thickened portions, upper 17 and lower 18, which slide inside the sleeves 13 and 15 respectively.

The lifting of the plunger plunger 16 is limited by the contact of the upper end of the thickened portion 17 with the shoulder 19 of the cover 12.

The plunger 16 can be lowered from this position by a stroke equivalent to the distance 20, shown in fig. 1, until the stop 21 is stopped, fixed on the upper end of the plunger 16.

During the race, the thickened portion 17 remains sealed with the sleeve 15 due to the O-ring 23, sealing the reservoir 11, but when the plunger 16 is pushed down, the seal extends beyond the lower end of the sleeve 15 to constitute a way out of the reservoir 11, through the gap between the lower thickened portion 18 and the sleeve 15.

The cylindrical portion 24, which contains the pressure chamber 25, is threaded with the lower part of the cylindrical body 10. At the lower end of the cylindrical portion 24, the nozzle 26 is threaded. Tightened and secured between the upper end of the nozzle 26 and the lower part of the annular border 27 , in solidarity with the cylindrical portion 24, is a capsule 28, containing the particles to be injected.

The capsule 28 is watertight relative to the nozzle 26 and the annular border 27 through the O-rings 29 and 30, buried in the nozzle 26, respectively, the capsule 28.

As can be seen in Fig. 8, the capsule 28 comprises an annular portion 31 with the truncated inner part surrounding the compartment 32 containing the particles to be injected. The upper part of the compartment is closed by a relatively fragile diaphragm 33 of Mylar, and the lower part of a more resistant diaphragm 34 of Mylar. The two diaphragms can be sealed by the upper and lower walls of the ring 31 by compression between the nozzle 26 and the annular border 27, but are preferably attached to the faces of the ring 31 so that the capsule 28 forms a sealed unit.

The diaphragm 34 can be waved down, as indicated by the dotted line in Fig. 8, to ensure the mobilization of all particles in the compartment when the diaphragms are broken during use. The ring 31 may consist of two parts, between which a third diaphragm is arranged, forming two separate compartments.

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The passage through the nozzle 26 shows a converging upper portion 35 (downstream of the flow), connected by the neck 36 with the divergent portion 37. The converging portion 35 is a continuation of the inner truncated inner portion of the ring 31. The nozzle is surrounded by a tubular portion made up of the divergent portion of the spacer 38 and the cylindrical portion 39 of the noise attenuation, formed in its turn of two halves separated by a longitudinal diameter plane.

The upper ends of the two halves come in contact with a cylindrical surface 40 of the nozzle 26, being held in position by the inter-engagement between an annular shoulder and the channel 41, the two halves being then united.

The inner surface of the cylindrical part 39 is formed by a number of flanges 40 which are axially spaced and projecting radially inwards.

The outer surface of the nozzle is provided with a number of complementary flanges 41, extending radially outward, each being axially spaced equidistantly from the adjacent pair of flanges 40. The outer diameter of the complementary flanges 41 is slightly larger than the inner diameter of the flanges 40 Near the top end of the cylindrical part 39 are the outlet openings 42, arranged in a ring.

The cylindrical body 10 is intended for reuse, being made of metal or plastic. The threaded parts at the bottom of the cylindrical body 10 will be made primarily of plastic and will be disposable.

In another embodiment, the entire syringe without needle will be made of plastic material, being supplied in sterile packaging and used only once.

The reservoir 11 of the cylindrical body 10 is charged with gas, for example, helium under pressure, by threading a feed tube on the sleeve 15 and lowering the plunger 16, so that the reservoir is charged by raising the gas near the thickened portion 18.

When the button 21 is released, the plunger 16 will rise, sealing the reservoir 11, due to the pressure exerted on the lower part of the thickened portion 18.

The remainder of the needle-free syringe according to the invention will normally be supplied in a sealed sterile package, with the capsule 28 positioned and the nozzle passage 26 filled with a light gas, such as helium, at atmospheric pressure, the sealing being accomplished by a film 43 bonded with adhesive to the lower end of the nozzle and provided with a sealing cord 44. This assembly is threaded by the cylindrical body 10.

To perform the injection, the wider end of the spacer 38 is pressed onto the patient's skin and after removing the foil 43, pulling on the sealing cord 44, the button 21 is pressed.

The gas released from the reservoir 11 into the pressure chamber 25 creates sufficient pressure to break the diaphragms 33 and 34 and allow the gas to pass through the nozzle 26 together with the entrained particles into the patient's skin.

The shock wave reflected by the patient's skin rises through the labyrinth space between the nozzle 26 and the surrounding cylindrical portion 39, on the winding path between the flanges 40 and 41, possibly exiting through the opening 42, attenuating the noise produced by the gas distension.

A single loading of the tank 11 may be sufficient for 5 ... 10 injections, although the prototype presented allows a single injection, before which the tank must be refilled. After injection, at least the disposable parts attached to the lower part of the cylindrical body 10 should be discarded.

However, in certain situations, the nozzle 26 may be unscrewed by the lower portion 24 and a new capsule 28 positioned before a new injection. If the reservoir 11 contains sufficient gas for several injections, the plunger 16 will preferably be held in the raised position by a spring, so that the lower end of the reservoir 11 is again sealed after releasing the button 21, after injection.

RO 118569 Β1

Fig. 4 shows a modified variant of the needle-free syringe, in which the upper end of the cylindrical body 10 is opened, the cylindrical portion 10 being caught at the lower end by a coupling 45, which is threaded by the upper end of the lower cylindrical portion 24.

The coupling 45 has a housing with an O-ring 46 for inserting and sealing the neck 47 of the metal tank 48 inside the housing, the tank containing pressurized gas, for example helium, and positioned lightly inside the cylindrical portion 10.

The lower wall of the coupling 45 is provided with an upward projection 49 through which a passage 50 passes, opening into the pressure chamber 25. A pair of arms 51, lowering on the opposite sides of the cylindrical body 10, pivots towards the cylindrical portion 10 in zone 52, near their lower ends, and in area 53, near their upper ends, relative to a lever 54 having a cam profile 55, intended to engage the upper end of the metal tank 48.

The neck 47 of the metal tank 48 contains a valve pressed by a spring, which is opened due to the pressure inside the neck of the tank 48, exerted by the upward projection 49, when the lever 54 is rotated clockwise, as shown in FIG. .4, in order to force the tank 48 to enter the housing.

The parts under the pressure chamber 25 are shown only schematically, in Fig. 4, but may also include the spacer / noise attenuator and the sealing foil shown in Figs. 1 ... 3.

The operation is analogous to the first embodiment, when the pressure chamber 25 is to be pressurized for injection, the lever 54 is actuated to release the gas from the tank 48 into the chamber 25. In this case, some or even all parts may be disposable.

In the first two embodiments of the needle-free syringe, a semipermeable membrane, which filters bacteria and any foreign bodies from the gas reservoir, may be fixed circumferentially by the cylindrical portion 24, for example, between two parts of the cylindrical portion 24, connected by threading, extending transversely inside the portion 24, upstream of the capsule 28.

Fig. 5 shows a modification of the first embodiment, and, although not shown, the spacer and noise attenuator, as well as the sealing foil may be included as in the first example. The essential difference is that the cylindrical portion 24 is longer and provided with a piston 56, sealed with respect to the inner wall of the cylindrical portion 24 through the O-ring 57. The piston 56 is retained inside the cylindrical portion 24, due to the annular shoulder 58.

In this case, the pressure chamber 25 may be pre-filled with gas, for example, helium at an atmospheric pressure of about 2-4 bar, even up to 10 bar.

During use, the button 21 will be pressed to lower the piston 56 over a short distance in the cylindrical portion 24, after which the gas released from the reservoir 11 will enter the cylindrical portion 24 through the back of the piston 56 and push the piston 56 into the pressure chamber 25 , until the pressure between the piston 56 and the capsule 28 becomes sufficient to break the diaphragm of the capsule 28.

In this example, it is provided that the cylindrical portion 24 is separated from the cylindrical body 10, to be thrown together with the piston 56.

The needle-free syringe shown in FIG. 6 and 7, has disposable parts similar to those of the needle-free syringe shown in FIG. 5, except that the piston 56 is slightly modified and contains a disc valve 59 through which the pressure chamber 25 can be preloaded with gas at atmospheric pressure.

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R0118569 Β1 In this case, the cylindrical body 10 contains a sliding plunger 60 having an annular conductive end 61 which engages the piston 56 around the disc valve 59.

The sliding plunger 60 is initially held in a retracted form, contrary to the action of a pair of parallel helical compression springs 62, via a plate 63 with a "key hole" slot, which can slide laterally in the upper part of the cylindrical body 10 and engages an annular groove at the top of a rod 64 threaded into an extension 65 of the upper end of the plunger and forming an extension of the plunger.

The helical springs 62 act on the extension 65 and a shoulder of the insertion 66 inside the cylindrical body 10, the plate 63 being able to slide laterally by actuating the arm 67.

Initially, the plunger 60 is withdrawn and secured, the plunger 56 being at the upper end of the pressure chamber 25, a spacer element from the lower end of the syringe without needle being applied to the patient's skin. Pressing the arm 67 results in the release of the rod 64 and the plunger 60, which pushes the piston 56 until the pressure in the pressure chamber 25 is sufficient to break the diaphragm 33 of the capsule 28.

In each example presented in this description, the geometry of the passage of the nozzle 26 and of the spacer element 38 is of importance, the following dimensions being characteristic of a speed of 2 Mach per nozzle.

The converging portion 35 is 10 mm long and converges from a diameter of 6 mm to a diameter of 1.5 mm of the neck 36.

The divergent portion 37 is 50 mm long and the values ​​of the diameters every 5 mm from the neck 36 to the outer hole of the nozzle 26 are 1.74; 1.95; 2.03; 2.10; 2.16; 2.19; 2.20; 2.21; 2.22; 2.23 mm.

The spacer element 38 has an axial length of 30 mm and its diameter increases from 12 to 30 mm.

The examples shown in FIGS. 5 ... 7 can be modified for laboratory use by providing in the wall of the cylindrical portion 24 of an inlet port connected with a helium source, through which the pressure chamber 25 can be intermittently filled up to a pressure. of 2 ... 4 bar.

In this case, it is not necessarily necessary that the underside of the syringe without a needle is disposable, nor is it supplied pre-assembled.

Thus, the cylindrical body 10 may have a rigid construction and be held in a fixed position. The sprayed material may be inserted between the diaphragms 33, 34 of a sealed unit 28 positioned between the cylindrical body 10 and the nozzle 26.

However, in the laboratory, a single membrane may be sufficient, on which the pulverized material is dosed through the upper part of the cylindrical body 10, prior to the insertion of the piston 56 in the upper part of the cylindrical body 10 and by raising the pressure inside the cylinder through the inlet port, after which the carrier gas is applied to push the plunger 56.