Device for dispensing liquid in the form of drops

A device for dispensing liquid including a liquid reservoir which can be deformed so as to dispense liquid by pressing on the reservoir, a liquid-dispensing end piece fitted on the reservoir, a channel for the passage of liquid, a channel for the passage of air from the outside to the inside of the reservoir, the channel for the passage of air being closed off by a member made of an air-permeable polymeric material, this material being non-porous, the member being called the air-permeable member.

FIELD OF THE INVENTION

This invention concerns the field of liquid dispensing, especially in the form of drops, in the pharmaceutical field, for example ophthalmic liquid.

BACKGROUND OF THE INVENTION

In particular, the invention concerns the dispensing of preservative-free liquid, in the form of drops, using a deformable reservoir with air intake.

The current trend is to supply products, especially ophthalmic products, that do not contain preservatives. The sterility of the product must thus be guaranteed throughout the use of the bottle containing the liquid to be delivered.

From document WO92/01625, various devices are known that enable the delivery of drops of product contained in a reservoir and which prevent contamination of the liquid remaining in the bottle.

According to one example, such a liquid-dispensing device includes a reservoir and a dispensing end piece fitted on the reservoir, provided with a liquid-dispensing opening. The user applies pressure to the reservoir causing it to become deformed and, under the effect of pressure, a drop forms on the surface of the dispensing opening. Once the drop has been dispensed, the user releases the pressure on the deformable reservoir, which tends to take up its initial shape, generating a depression inside the bottle. To fill this depression and allow the reservoir to return to its initial shape, the end piece of the device comprises an air inlet in the reservoir. To ensure that the incoming air cannot contaminate the liquid remaining in the reservoir, a hydrophobic filter is fitted in the air channel. This filter allows the exterior air to enter the reservoir while avoiding the entry of microorganisms and dust, and preventing liquid from entering or leaving.

One problem with this type of device lies in the fact that it is difficult to guarantee its reliability. It is in fact difficult to test correct operation of the filter after fitting on the end piece, since the filter would have to be tested under water, which implies a risk of contamination or degradation during the test phase. It is therefore difficult to guarantee the integrity of the filters used and of their assembly on the end piece.

The present invention is intended to provide a device for dispensing liquid which reliably guarantees the sterility of the dispensing end piece.

SUMMARY OF THE INVENTION

An object of the invention is therefore a device for dispensing liquid, characterised in that it comprises:a liquid reservoir which can be deformed so as to dispense liquid by pressing on the reservoir,a liquid-dispensing end piece fitted on the reservoir,a channel for the passage of liquid,a channel for the passage of air from the outside to the inside of the reservoir, the channel for the passage of air being closed off by a member made from air-permeable polymeric material, this material being non-porous, the member being called the air-permeable member.

It is therefore proposed to perform the function of allowing uncontaminated air into the reservoir, not by filtering the air but by using the gas diffusion properties of some materials. A member made from non-porous polymeric material is therefore used instead of a filter. This type of member offers the advantage of allowing uncontaminated air to flow in a way that is more reliable than with a filter, which is porous by definition. With a non-porous member, in fact, there is no need to test the pore size and it is easier to check that there are no leaks due to poor assembly or a defective member.

A “non-porous” material means a solid material, with no holes, blocking the passage of particles such as bacteria, for example blocking bacterium Brevundimonas Diminuta which has a diameter of about 0.2 micrometers. This non-porous material differs from a filter, which is designed to be porous. The non-porous material proposed for the air-permeable member is in fact composed of a polymer used in its raw form, having undergone for example simple injection or compression, whereas a porous material like that of a filter is composed of a polymer which has also undergone steps to generate pores or interstices, for example stretching of the material or addition of a chemical solvent in the polymer. Since the material is non-porous, it is liquid-tight and blocks the passage of particles such as dust or microorganisms. This material is air-permeable, however, since it allows elements of the size of a molecule to pass through. In other words, the non-porous material proposed above is permeable to gases and allows the air molecules to pass, through a cross-linked network of long tangled molecular chains. In other words, the member made of non-porous material is configured to allow air to pass by diffusion across the air-permeable member. One can see that, since the material is non-porous, air takes several minutes, or even hours, to cross the member, not just a few seconds as is the case for a filter. For a device used to dispense 240 μL of liquid, for example, the depression is almost completely compensated, i.e. the pressures inside and outside the bottle are almost the same after just 12 hours. The time required to return to a pressure more or less equal to the external pressure may seem long, but the inventors of the invention observed that this is not really a problem for application to dispensing of drops.

When the user releases the pressure on the reservoir, after having pressed it to dispense a drop of liquid, the depression between the inside and outside of the bottle is slowly compensated by the flow of external air across the air-permeable member.

It is to be noted that since this member has no pores, there is no risk of clogging due to an accumulation of microorganisms and dust in the pores. In addition, there is no risk of liquid capillary pressure, which would oppose the return to pressure equilibrium between the inside and the outside of the reservoir when the device is upside down and the liquid is in contact with the air-permeable member. These two phenomena are present when a filter is used.

This type of member is very easy to test. All the blocking members can be tested after fitting on the end piece, without contaminating or degrading the member. These types of test are more advantageous than those performed on filters, which are likely to contaminate or degrade them during the tightness test, or for which only statistical tests can be conducted, on samples destroyed during the test, producing relatively limited information.

The members can be tested for example by applying air pressure on one side of the member and measuring the pressure on the other side after a few seconds. Since the process allowing the pressures on each side of the member to return to equilibrium takes several minutes, or even hours, and not just a few seconds, the time scale is not the same as when testing a filter. At the scale of the second, therefore, it will be impossible to detect a pressure loss on a non-defective member, whereas there will be a noticeable pressure drop if the member is defective or badly fitted on the end piece. This test can therefore be used to identify all defective parts. It is to be noted that the air-permeable member can be manufactured easily and cheaply. It therefore differs from the hydrophobic filter, which is very expensive to manufacture, firstly to guarantee fine filtration and secondly to guarantee its integrity.

The dispensing device may also comprise one or more of the following characteristics.

The air-permeable member further comprises at least one channel for the passage of liquid. A member offering a large exchange area with the reservoir can therefore be planned.

The channel for the passage of liquid is a liquid flow limitation channel opening to the channel for the passage of liquid. It is therefore possible to limit the flow of liquid leaving the reservoir and avoid dispensing the liquid in a stream if the user exerts too much pressure on the reservoir. The air-permeable member can therefore be used to act as flow limiter, which makes it easier to assemble the end piece, by reducing the number of parts to be assembled. According to one example, the diameter of the flow limitation channel is relatively small compared with that of the channel for the passage of liquid, or the flow limitation channel has sudden changes of direction, which reduces the pressure.

The end piece and the member each has a central axis, the two axes being colinear. This makes it easier to fit the member on the end piece. It is in fact easy to centre one part with respect to the other. In addition, by placing the air-permeable member in the centre of the device, it can be designed to have a relatively large area, for example covering the entire neck of the device reservoir, thereby offering a larger area for the flow of air, so that the internal and external pressures reach equilibrium as quickly as possible.

The member comprises a so-called air passage wall, equipped with a plurality of reliefs, to increase the air passage area. For example, the wall could be corrugated, have a sinusoidal, castellated or saw-tooth cross-section. This increases the air exchange area between the inside and outside of the reservoir without making the member very much larger. The flow of air that can pass through the member wall by permeability is in fact directly proportional to the exchange area and inversely proportional to the thickness of the member wall. A large exchange area and a thin wall improve the air intake. The member wall geometry can easily be modified by varying the exchange area and thickness parameters to adapt to the rate of air intake required. The reliefs formed on the wall differ from ribs, they are made in parallel on both sides of the member wall, the wall thickness being substantially constant along the reliefs and small enough to allow air to flow, so as to increase the exchange area of the air-permeable member.

The member comprises stiffening ribs. This ribs make the member more rigid. Such ribs correspond to local increases in the thickness of the member wall, to make it more rigid, thereby forming projections on one of the two sides of the wall. These ribs therefore differ from the reliefs described above, whose purpose is to increase the exchange area.

The member has a generally cylindrical or conical shape, with a base comprising a collar for fastening to the end piece. The thickness of this collar is preferably greater than that of the air passage wall, so that it is rigid enough to fasten the member, for example by mechanical tightening. The collar may possibly comprise mechanical fastening means, which cooperate with means on the end piece, for example by snap fastening. Through the use of the collar, the member fits easily on the end piece and requires no complex fastening means. In addition, for a given end piece, it is easy, depending on the required air intake characteristics, to propose a member whose air passage wall can have different configurations, while retaining a standard collar which adapts to the end piece.

The channel for the passage of liquid is defined by an outer annular surface of the air-permeable member. Consequently, there are no holes through the air-permeable member allowing the passage of liquid, which means that the air passage and the liquid passage can be separated.

The polymeric material comprises an elastomer material. Since the member can be deformed, it may possibly be fitted on the end piece by slight deformation. Once in position, the member can return to its initial shape and be fastened by mechanical tightening in the end piece, which simplifies its positioning. In addition, due to the flexibility of the elastomer, it is easier to avoid gaps between the member and the end piece, by adapting the member contact surfaces with the end piece walls.

The polymeric material includes silicone (also called polysiloxane, an inorganic compound consisting of a silicon-oxygen chain). The permeability of silicone to gases further improves the air intake process, shortening the time required. Silicone also offers the advantage of being inert with respect to pharmaceutical liquids.

Liquid dispensing is controlled by a single valve, which can either take a configuration for blocking liquid or a configuration for dispensing liquid. The device therefore differs from a dispensing device equipped with a pump, device in which there is no need to deform the reservoir to dispense liquid.

The device includes a valve and a support comprising a valve bearing surface to block the passage of liquid, the support comprising the channel for the passage of air and the air-permeable member being attached to the support. The device obtained is therefore highly compact.

The time to balance the pressures inside and outside the reservoir after dispensing liquid is greater than 30 minutes, preferably 1 hour. Although the air intake occurs through a member which does not allow the reservoir to return to its initial configuration almost instantaneously, this disadvantage is offset by the fact that the device proposed guarantees that the air coming from the outside is not contaminated. It is to be noted that this time to return to the initial configuration is greater than 30 minutes or even 1 hour, even if the sealing member is used under optimum conditions, being completely clear. In other words, even when the device is not used upside down (in which case water is in contact with the member) and when it contains no impurities, the gas diffusion time is relatively long, unlike filtration by a filter, when this time is almost instantaneous or at least only about few seconds.

Another object of the invention is a set of two devices as described above, including two identical end pieces, equipped with air-permeable members each having a different configuration. For example, the members have different thicknesses or shapes.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows an end piece10for dispensing liquid in the form of a drop, for screw mounting onto the neck of a reservoir12. This reservoir12is a storage reservoir for a liquid, for example pharmaceutical liquid such as ophthalmic liquid. The reservoir12can be deformed so as to dispense liquid by pressing on the reservoir. More precisely, the liquid is dispensed by pressure, applied by a user, on the body of the reservoir12, the latter having a certain elasticity to enable it to return to its initial shape after the pressure exerted by the user is released, generating a depression inside the reservoir12.

In this example, the dispensing end piece10comprises a support14, a dispensing valve16equipped with a dispensing opening18, a spring20, an outer envelope22, a channel24for the passage of liquid from the reservoir12to the dispensing opening18and a channel26for the passage of air into the reservoir12, channel26being closed off by an air-permeable member28.

In this example, the support14comprises a part32for fastening to the reservoir, placed at the proximal end of the support14. The part32comprises an external skirt34including a screw thread enabling it to be screwed onto the neck of the reservoir12. The fastening part32also includes a tubular internal skirt36, enabling it to ensure the seal between the reservoir12and the dispensing end piece10.

Furthermore, the support14includes a central sealing part38, substantially cylindrical in shape and extending in the distal direction, opposite to the internal skirt36. The part38comprises, on its distal end, a bearing surface40of the valve16to block the flow of liquid in blocking configuration. In this example, the bearing surface40has an annular bead shape.

In this example, the support14also comprises the channel26for the passage of air into the reservoir12, which opens to a substantially cylindrical cavity42. This cavity42opens, at its proximal end, to the member28.

In this example, the support14also comprises a housing44forming a substantially cylindrical cavity, this cavity opening to the reservoir12at its proximal end and opening to the channel24for the passage of liquid at its distal end, formed in the support14and extending in the longitudinal direction of the device, corresponding in this case to the direction of liquid ejection illustrated by the arrow46. Channel24opens to an intermediate cavity48, itself opening to a second channel50for the passage of liquid.

The housing44is next to the cavity42, being separated by an annular wall52, extending in the direction opposite to the sealing part38.

The air-permeable member28is made of an air-permeable polymeric material, this material being non-porous, blocking the passage of particles such as bacteria of diameter 0.1 micrometers, but allowing molecules, such as air molecules, to pass. Air therefore passes through the air-permeable member28by diffusion across the member28. The polymeric material comprises an elastomer material, silicone in this example. The member28has a generally cylindrical or conical shape. Its central axis is colinear with that of the end piece10, this axis corresponding to the liquid-dispensing direction, therefore to the arrow46. More precisely, in this example the member28comprises a so-called air passage wall, which is relatively thin to improve the exchange of gases, cylindrical or conical in shape, with a top closed off by a disc-shaped surface and a base comprising an annular collar30for fastening on the end piece10, this collar30being relatively thick, at least thicker than the general thickness of the air passage wall.

The member28is housed in a substantially cylindrical cavity54bounded by the internal skirt36of the support14and is fastened, in this example by mechanical tightening, by cooperation of the collar30with the annular wall52. More precisely, the inner diameter of the collar30is slightly less than the outer diameter of the wall52, such that the collar is held against the wall52by elasticity. If necessary, snap fastening means such as an inner annular bead formed on the collar30snap fastening into an annular groove formed on the outer surface on the wall52may be planned in addition to the mechanical means for fastening the collar30on the wall52. Mechanical attachment means crossing the part14to reach the cavity48or means for attaching onto the inner wall of the cylinder36could also be planned.

In addition, the support14comprises a part56for fastening the valve16on the support14. This part56also acts as part used for fastening the outer envelope22on the support14. It comprises an annular groove58bounded on the periphery by an annular wall60. The annular groove58is also bounded, on its inner periphery, by an annular rib created on a wall substantially forming a disc, crossed by the channel24and bounding the cavity48.

The valve16can take a configuration for blocking liquid and a configuration for dispensing liquid, by cooperation with the support14. In this example, it is made from an elastomer material. According to another example, only part of the valve16is made from an elastomer material, the other part being made from a more rigid material which can act as seat for the spring20. The valve16comprises a part62for fastening to the support14, forming a substantially tubular skirt. This fastening part62is connected to a substantially disc-shaped web64and from which a substantially cylindrical central part66projects out. The web64also comprises a seat68for the spring20. The part66forms a substantially cylindrical inner cavity, complementary to the part38. The part38and the cylindrical part66are coaxial and jointly bound the channel50for the passage of liquid. This channel50for the passage of liquid opens to the dispensing opening18formed in the distal end of the valve16, itself opening to a shape68for forming drops.

The outer envelope22comprises an annular part70for fastening on the support14, as well as another annular part72, coaxial with the part70, so as to form a groove74housing the annular wall60. The outer envelope22also comprises a seat76for the spring20, extended on its inner periphery by an annular wall78, crossed by the part66and designed to centre the part66of the valve16.

In addition, in this example, the air-permeable member28comprises at least one channel80for the passage of liquid. Also in this example, the channel80for the passage of liquid acts as flow limiter for the liquid, opening to the channel24for the passage of liquid. More precisely, the collar30of the member28comprises on its outer annular surface a plurality of grooves80, shown in particular onFIGS. 2ato2d, and delimiting, with the housing44, channels82for reducing the flow of liquid. These channels82have a relatively small diameter to reduce the liquid pressure when the user presses on the reservoir. According to an alternative embodiment, the grooves80could have changes of direction or a spiral shape. Depending on the number and size of the grooves80placed opposite the housing44, the flow of liquid coming out will be more or less reduced.

For example, the member28can take one of the shapes illustrated onFIGS. 2ato2d. The reduction shapes80are made on the outer periphery of its collar30, forming a recess in the periphery.

On the examples ofFIG. 2a, the member28comprises a thin air passage wall, of substantially cylindrical or conical shape. To make it more rigid, the wall also comprises stiffening ribs84, corresponding to local increases in the thickness of the wall.

The members28ofFIGS. 2bto2dillustrate other types of member28on which the air passage wall comprises, instead of or in addition to the stiffening ribs84, a plurality of reliefs which increase the air exchange area between the inside and outside of the reservoir12without making the member28very much larger. These reliefs are formed in the wall so that it remains relatively thin to allow air to pass. In addition, these reliefs can be used to make the member28more rigid, possibly avoiding the need for the stiffeners84, as shown in particular onFIG. 2cwhich illustrates a corrugated air passage wall, having a clover-shaped cross-section.

The operation of the device shown onFIG. 1will now be described.

At rest, i.e. when no user is pressing the reservoir12, the valve16is in configuration for blocking liquid, i.e. it presses on the surface40, since it is permanently fastened to the support14, exerting an elastic force on the valve, and due to the pressure exerted by the spring20.

A user pressing the reservoir12exerts a pressure on the fluid which flows into the only channel allowing it to flow, i.e. the channel82for passage of liquid and, in this example, for reducing the flow, since a liquid cannot go through the walls of the member28. As it passes through this channel82, in this example, the fluid flow rate decreases, due to the pressure drop. The fluid then flows in the channel24, then in the cavity48and in the channel50. Under the effect of the pressure, the fluid lifts the valve16, which then switches into configuration for dispensing liquid, and can therefore flow between the valve16and the bearing surface40, to pass in the channel18and in the cavity68, and therefore take the form of a drop.

Once the drop has been dispensed, the user releases the pressure on the deformable reservoir12which tends to take up its initial shape, generating a depression inside the reservoir12. This depression will be compensated by an intake of exterior air from the channel26for the passage of air through the air-permeable member28. Note that, since the material forming the member28is non-porous, air takes several minutes, or even hours, to pass through the member28, not just a few seconds.

Thus, if we consider a device containing 12 mL, filled with 10 mL of an ophthalmic solution and equipped with an air-permeable member comprising silicone which has an oxygen permeability of 1.4*10−13mol*m−1*Pa−1*s−1(mol per metre per Pascal and per second) and an exchange area of 90 mm2and a thickness of 0.4 mm, dispensing 6 drops of solution under atmospheric pressure, i.e. 40*6=240 microliters of liquid, creates a depression of about 95 mbar which will be almost completely compensated in 12 hours (more precisely, about 90 mbar will be compensated after 12 hours).

Since the wall of the member28is not porous, this time required for air intake into the reservoir12is approximately the same, whether or not the device is upside down.

It is to be noted that since the member28is a separate part, its shape can be changed to suit the applications, the air intake times required and the flow rate reductions required. It is therefore possible to manufacture sets comprising end pieces with the same valve16, the same support14, the same outer envelope18, but with different members28.

The invention is not limited to the previously described embodiments.

One can see that it is especially advantageous to use a non-porous material such as that used for the member28, since it is very easy to check that this member is functional. If a hydrophobic filter had been used instead of the member28, it would have been difficult to test, after assembly, that the filter does not leak.