HK1243911B - Device for dispensing liquid from a sterile packaging bottle - Google Patents

Description

The invention relates to liquid dispensing devices used in bottling techniques for packaging products that must be kept sterile not only until the bottle is opened, but also throughout the product's consumption period until the complete emptying of the bottle's contents.

As a typical example of the needs that the invention aims to satisfy, we will consider the field of multi-dose bottles, which receive aqueous solutions to be dispensed intermittently in staged doses over time, and are equipped with air/liquid interface membranes that prevent the passage of microbial contaminants from the ambient air into the bottle by means of filtration.

Such membranes are also known, which have the additional property of being doubly selectively permeable, allowing air or liquid to pass through them preferentially depending on a pressure differential acting between their two sides. This occurs alternately from upstream to downstream during the phase of expelling a dose of liquid out of the bottle, and from downstream to upstream during the aspiration phase when air is drawn into the bottle to volumetrically compensate for what has been extracted. The existing patents of the Applicant describe how such membranes,They are referred to as bifunctional (bifunctional from the perspective of liquid or gas flow transport), and are used to ensure an alternating circulation between liquid and air through a capillary discharge channel located after the membrane. Such membranes, which serve as an interface between the closed space of a sterile packaging bottle for an aqueous liquid (in particular, an aqueous solution of a pharmacologically active ingredient), are partially made of a hydrophilic material on a first area of the entire interface surface, and partially made of a hydrophobic material on a second area of the same surface.The operation of such a membrane is described, for example, in the French patent published in the application state under number FR2872137 (corresponding international application WO 2006 000897), for a membrane positioned across a single conduit allowing air and liquid flows to pass in both directions between the inside and outside of a flexible-walled bottle, which is manipulated to alternately expel and aspirate.

In such a context, the invention aims to provide a liquid distribution device with microbial protection, offering high safety regarding both microbial sterility and chemical toxicity in its application to sterile liquid product containers, where sterility must be maintained throughout the consumption of the contents of the container, during successive distribution operations carried out over time. Enabling extended periods of gradual consumption is a major objective sought through this, another being to allow multi-dose packaging for pharmaceutical or parapharmaceutical products applied on highly contaminated surfaces.

With these objectives in mind, the invention proposes to use a bifunctional hydrophilic-hydrophobic membrane that is furthermore charged throughout its mass with a biocidal agent by means of ionic oxidation effect. Such an agent is particularly provided by macromolecules carrying positively charged metal ions, such as those proposed in a well-known prior art in the form of mineral polymers from the family of alumino-silicates, called zeolites, which retain labile metal cations within their structure. Among the useful ions, silver ions (Ag+ or Ag++) have proven to be the most advantageous in the industrial context of anti-bacterial protective membranes implemented according to the present invention.

In a liquid dispenser according to the invention, such a membrane is used as a permanent source of biocidal metal ions in combination with a porous mass placed along the fluid path upstream from the membrane. This mass is designed to retain the biocidal ions that reach it, having been extracted from the membrane during the suction phase of each liquid dose distribution operation. Thus, it forms a secondary reserve of active ions while acting as a buffer regarding the transport of these ions, preventing them from reaching the internal receiving space of the bottle. In practice, it has been observed that the ions thus stored, if not consumed on site, are easily released and carried back toward the membrane during the ejection phase of a subsequent distribution operation.

Cationic metal-charged air/water interface membranes with biocidal effects have been known for a long time, as evidenced, for example, by the American patent US 5,681,468, filed in 1993 and published in 1997. However, it had never been considered that these biocidal cations could act in any other way than by attacking bacteria contaminating the liquid expelled when it is downstream of the membrane after passing through it. Similarly, it had never been proposed to install the membrane as provided by the invention, within a device combining the membrane with a porous mass retaining the same active ions as those charged on the membrane, as well as means for organizing the flow of fluids through them, ensuring the alternation of flows at the level of the membrane and in the downstream area of the device.

In the practical implementation of the invention, this porous mass is designed in the form of an insert mounted in the liquid distribution device, upstream of the membrane, as a non-airtight closure plug of the communication duct between the inside and outside of the bottle. By its porosity and arrangement, the insert is advantageously designed to perform the function of flow regulating buffers known from the eye drop bottles described in the Applicant's previous patents, by imposing a pressure loss on the liquid path exiting the bottle.

On the other hand, for such an insert to perform its role in protecting against sterility pollutants as intended by the present invention, it is specifically made of a polymer material containing active sites with a negative charge, which are thus able to attract biocidal metal cations with which the membrane is initially charged. From this perspective, the preferred materials are polymers based on polyolefins copolymerized with carboxylic acid functional compounds. Depending on the relative proportions of the components and the conditions under which the copolymerization reactions take place, a significant proportion of free carboxyl sites remains in the resulting polymer, ready to bind with the cations used as biocidal agents that come into contact with the polymer.

According to a preferred implementation mode of the invention, the specific ion retention capacity of the polymeric material for metal cations can be increased by subjecting the polymer to an irradiation treatment that has the effect of releasing other carboxyl groups.

The operating mode of the device according to the invention as a whole will be specified in the following description by referring to the case where it is fitted to a sterile packaging vial of a flexible-walled, elastically compressible internal reservoir containing an ophthalmic solution. However, it should be understood that other means may also achieve similar pressure variations, causing, during each dispensing operation of a liquid dose, first a propelling phase in which the liquid is pushed from inside to outside the vial and expelled beyond the capillary channel located downstream of the membrane, then an aspiration phase drawing external air back into the vial.The air is then preceded by a reflux of non-expelled liquid. One may particularly think of a bottle with an axially movable bottom against an elastic return means, or a bottle equipped with a pump system. On the other hand, it is preferable to refer to a drop dispenser device, but it should be understood that the device according to the invention can also be adapted for distributing larger individual doses than drops, as well as for discharging the liquid from the capillary channel in other forms, for example as a jet or with spatial diffusion.

Initially, during the entire storage period before first use, the bottle remains tightly sealed with a sterile air cushion pressurized over the liquid receiving space, so that the membrane remains dry. It will only become saturated with liquid in its hydrophilic area when the liquid is expelled for the first time after the bottle has been opened.

The downstream side of said device includes a capillary channel in which liquid flow and gas flow alternate, never mixing with each other, so that during operation, when the channel has finished conveying the liquid flow to be expelled outside, a residual amount of liquid remains temporarily occupying the channel. This residue is returned in reverse through the membrane under the pressure of the air flow drawn from outside when the pressure difference across the two sides of the membrane ceases to act in the expulsion direction. During this suction phase, the returning liquid passes through the hydrophilic area of the membrane, while the air entering to compensate for the volume of distributed liquid passes through the hydrophobic area.

Upstream of the membrane, the space provided in the following device forms a channel that, unlike the downstream capillary channel, has a larger cross-sectional area. It is within this channel that the porous insert providing negative charges is placed, which participates in reactions that tend to retain the biocidal metal cations carried by the liquid through chemical bonding with the polymer of the insert at its active sites, notably in the form of free carboxyl groups. This insert, also called "tampon" in French or "plug" in English, is located there in the presence of both liquid and air flows.Which come together at the contact with the polymer component in the cells of the porous material. The contact occurs on a large surface, corresponding to the specific surface area of the porous material. When the device is operating, the porous insert retains enough biocidal metal cations so that the liquid stored in the bottle cannot be chemically contaminated by biocidal cations. On the other hand, it ensures that there are back-and-forth movements of biocidal cations carried by the flow and return of the liquid, especially back and forth between the membrane and the porous insert, following a phenomenon that favors high biocidal activity in the said liquid distribution device while preserving the stored liquid from microbial contamination.

Indeed, surprisingly, the inventors have highlighted that the said device according to the invention maintains a strong biocidal activity throughout its entire usage time during intermittent liquid dispensing. As will be detailed further on, it has been shown that the dispensing device according to the invention, when sealed tightly in the closure of a bottle to create a multi-dose bottle, for example containing a sterile eye drop solution, exhibits high efficiency in terms of sterility during the consumption of the eye drops. The consumption of the contents can thus last much longer over time than with current bottles, and in complete safety regarding the absence of harmful effects for the patient.

The incoming air flow compensating for the expelled liquid, which comes from ambient air containing microorganisms, is mainly sterilized as it passes through the membrane by the biocidal action of biocidal cations in the pores of the membrane's hydrophobic part, and optionally by bacteriostatic filtration. Furthermore, if necessary, because biocidal cations carried by the residual liquid not yet expelled are retained in the insert at the end of each liquid distribution, there is always an active biocidal agent available to destroy microorganisms present in the stagnant air within said insert mixed with a portion of the residual liquid.

Further tests described later confirm that biocidal cations are gradually collected in the porous insert, following a decreasing quantity gradient from the most proximal extreme part, closest to the membrane, here called the proximal side, towards the most distal extreme part, closest to the liquid reservoir, here called the distal side, so that the liquid reservoir remains free of biocidal cations.

Furthermore, after the initial activation of the device by liquid distribution, the porous insert, which becomes charged with biocidal cations, then serves as a source of biocidal cations that can be partially extracted as the liquid flow exits the bottle through the insert to reach available sites on the membrane.

Thus, a back-and-forth movement of biocidal cations is created in the fluid circulation channel, due to the movement of the liquid, maintaining a relatively stable amount of biocidal cations available within the device according to the invention during use, so that they can be active against microorganisms coming into contact with them.

In principle, the invention thus appears to consist of realizing a bifunctional water/air interface membrane on one hand, and a buffer insert installed as an non-airtight stopper in the bottle on the other hand, such that during operation, after opening the bottle for the first use in liquid dispensing, the membrane and the insert cooperate to create a bed of mobile ions, which are taken from the insert by the liquid flow extracted from the bottle during each dispensing operation (during the liquid expulsion phase) from those that had been brought there by a reflux of undispensed liquid during previous liquid dispensing operations (during the air aspiration phase).

Overall, it can be accepted that the amount of biocidal metal ions actually consumed in the destruction of biological contaminants is very small compared to the amount displaced during each liquid distribution operation, which itself is very small compared to the initial capacity of the membrane. The amount consumed depends on the degree of contamination of the ambient air drawn in, and the air treatment efficiency will be better the larger the contact surface with the charged materials. The amount displaced depends on the liquid flow rate ensuring the transport of the active cationic charge, or more precisely, on the mass of liquid displaced during each liquid reflux from the membrane to the insert and each direct flow during ejection towards the membrane.

Keeping these considerations in mind, the liquid distribution device according to the invention can be adapted for use in environments with varying degrees of contamination, even under severe conditions in terms of the total volume of solution to be distributed, the total duration of bottle usage, and the frequency of repeated distribution operations. This can be achieved by adjusting the respective shapes and dimensions of the membrane and the porous insert, assuming that the materials composing each of them remain unchanged.

Regarding the membrane itself, the present invention advantageously provides that it is made from a porous polymeric material having hydrophilic properties, uniformly charged with a biocidal agent through ionic oxidation. This material constitutes the entire mass of the membrane and is then locally rendered hydrophobic by a complementary polymerization treatment, while preserving its biocidal activity. This treatment is applied to a portion of the membrane's extent that crosses the fluid circulation conduit between the inside and outside of the flask.

This makes it possible to provide an appropriate volume for the contact between the gaseous phase, consisting of air, and the polymer material charged with active ions by means of a biocidal effect within the porous mass throughout the entire thickness of the membrane. In the same way, the fact that the hydrophilic base material of the membrane is finely homogeneous excludes previous membrane filter designs made from fibrous materials that retain charged particles between the fibers. According to the invention, it is preferred to start from a melted polymer base containing fusible granules of a master batch that itself includes mineral macromolecules carrying active ions by means of a biocidal effect.

While traditionally, bacterial filtration requires a fine porosity not exceeding 0.2 µm, the presence of a biocidal agent within the membrane allows for satisfactory sterilization with coarser porosities, preferably around 0.3 or 0.4 µm, or even ranging up to 0.5 µm, or even up to 0.6 or 0.8 µm, or even 1 µm, which is advantageous in terms of pressure drop and enables the treatment of viscous liquids. In practice, the invention thus provides, according to a preferred implementation method, to produce the membrane such that it has an average pore diameter suitable for filtering microorganisms larger than particles with sizes between 0.3 and 1 µm, particularly between 0.3 and 0.6 µm. Overall, the membrane porosity can thus be adjusted to any value between 0.1 and 1 µm depending on the physicochemical properties of the liquid.

The macromolecules supporting biocidal ions are advantageously, as already mentioned, mineral polymers of the alumino-silicate type in which the biocidal ions are incorporated, specifically, in a manner that is itself known, metal ions such as silver ions or similar metals in ionic form, which bond to the free sites of the polysiloxane chains via polar covalent bonds. These mineral polymers are preferably crystalline polymers. The concentration of active ions in the membrane is preferably, although not limiting the application conditions of the invention, chosen to be between 100 and 100,000 ppm, taking as an example the case of a mineral polymer based on alumino-silicates carrying silver ions in a membrane with a pore size of approximately 0.2-0.3 micrometers and an effective area of about 3 cm².

Among the metal ions useful for the invention, copper and zinc ions can be retained; however, silver ions have proven to be the most advantageous in the industrial context of the antimicrobial protection device implemented according to the present invention.

As a secondary characteristic, the invention extends beyond the liquid distribution device according to the invention, to a sterile packaging bottle, particularly for use in the sterile packaging of pharmaceutical or par pharmaceutical products.

The invention also relates to a particular method for manufacturing the membrane itself.

Advantageously, means for organizing the flow of fluids complement the distribution device mounted on a packaging bottle. Preferably, said packaging bottle has an elastically deformable wall to allow the intake of outside air in compensation for any dose of liquid expelled from the bottle as well as the return flow back through said device of any remaining liquid not expelled. Said membrane is mounted together with said porous insert in said liquid distribution device, in association with means for organizing the circulation of air and liquid through it. In this arrangement, said membrane is positioned at the base of a dropper tip comprising the capillary channel for expelling drops, facing a base of said dropper tip in which are provided respective guiding means for the air drawn in from the outside and for any remaining liquid not distributed, which is intended to flow back through the membrane from the downstream side to the upstream side. Said guiding means tend to direct the air flow toward the hydrophobic part of the membrane, preferably located at the center of said membrane, and to distribute the liquid over its hydrophilic part.

Description of a method for manufacturing a bottle

The invention will now be more fully described in the context of preferred features and their advantages, with reference to non-limiting examples, by referring to a device for dispensing a sterile liquid according to the invention, in its application for maintaining sterility in a dropper bottle as illustrated in Figures 1 to 4, wherein: Figure 1 shows, in longitudinal section and exploded view, the different elements of a flexible-walled bottle from which a liquid is expelled in successive doses through a microbial protection dispensing device according to the invention; the longitudinal section of Figure 2 particularly shows the dispensing device, once its individual components are assembled to form a liquid dispensing head and an external air inlet that fits into the neck of the bottle; Figure 3 illustrates the configuration of the base of the dropper on its surface facing the housing of the device shown in Figures 1 or 2; Figure 4 shows, in partially exploded view, the return flow of fluids in the circulation channel of the dispensing device according to the invention represented in Figures 1 or 2.

In its general structure and as it is represented in all its elements on Figure 1, the bottle equipped with a dispensing head appears to conform to the usual design of sterile packaging bottles. The bottle includes a reservoir 2 receiving the aqueous liquid to be dispensed in a sterile state, topped by a sealed dispensing device mounted in the neck of the bottle 10. However, it differs by features specific to the invention, which are distributed among its essential components for the distribution under microbiological protection according to the invention, along the conduit for the aqueous liquid to be dispensed and the air entering in compensation for the expelled liquid, namely mainly upstream of this conduit, the porous insert 8 in the form of a buffer occupying the internal space within the housing 4, and at the interface between these downstream and upstream parts, the membrane 7. It also differs in their relative assembly related to fluid circulation and the effects on biocidal activity in the conduit that result from it.

According to the invention, the selectively permeable membrane included in the distribution device is used for separating liquid and air flows passing through it, as a microbiological protection membrane by filtration, and, due to its material containing mineral macromolecules carrying biocidal cations, for destroying bacteria or similar microorganisms carried in the fluids passing through it.

In the example chosen to best illustrate the invention, the membrane is based on an organic polymer, more specifically, in this case, it is made from a polyester resin modified by a polyamide or polyether-sulfone resin, into which mineral macromolecules supporting biocidal cations have been incorporated in bulk, particularly here, a cationic silver-charged zeolite. It is of a hydrophilic nature and is rendered hydrophobic over only part of its extent across the channel provided in the distribution device. For example, this is achieved by local exposure to ultraviolet radiation, which modifies the polymer structure in situ through radical cross-linking reactions between its components, while preserving the biocidal properties of the cations in the zeolites.

The membrane shown in Figure 4 thus has a hydrophilic area 22 that is preferentially permeable to the aqueous liquid in the presence of air, and a hydrophobic area 23 that is preferentially permeable to air in the presence of water or an aqueous liquid. The ionic charge with biocidal effect is present both in the hydrophobic area and in the hydrophilic area.

In operation, during successive liquid dose dispensing operations from the vial, spaced in time, the membrane structure, in conjunction with the organization of fluid flow through it, tends to promote a destructive action on microorganisms that takes place within the hydrophobic material itself, by contact between air and the ion-loaded polymer at the pore surfaces, whereas, conversely, in the hydrophilic part of the membrane, the biocidal ions are not consumed but carried further along by the liquid passing through the membrane.

Inside the fluid flow conduit, upstream of membrane 7 on the side of the closed internal space of the container, there is a porous insert 8 which, according to the invention, mainly serves to retain the biocidal cations brought by each return flow of aqueous liquid consisting of the residue not expelled from the previously withdrawn dose of liquid from the container, and to release again toward the membrane the biocidal cations it has collected when subsequently a new dose of liquid is expelled from the container.

In classic examples within the framework of ophthalmic applications, the porous insert has a length along the axis of the vial of 9 mm and a diameter of 9.6 mm. More generally and by way of indication, said insert may have a length ranging from 5 to 15 mm. The dimensions of the insert are adapted to the size of its receptacle.

Its distance from the membrane, as measured on its upstream side, is of the same order of magnitude. Its porosity corresponds to an air flow rate of 3,000 ml/min, as measured using the "water flow" capacitive method, which consists of measuring the time required to fill a given volume using a stopwatch. Its bulk density is approximately 0.50 g/cm³, as shown in the example.

More generally, the insert comprising a large number of open cells exhibits a porosity preferably corresponding to an air flow rate between 1,000 and 4,000 ml/min, measured according to the capacitive "water flow" method. Its bulk density is preferably between 0.20 and 0.80 g/cm³.

Porous Insert Acidity Tests

The porous insert intended for an eye drop bottle, as considered in this example, is made from an extruded polymer filament based on polyethylene that undergoes compaction. The polymer contains carboxylic groups initially because ethylene has been copolymerized with carboxylic acid functional compounds, such as higher homologs (hydrocarbon chains of C4-C10) of carboxylic acids, in a proportion of at most 25%.

At this stage, it already contains carboxyl groups that remain free as a result of the polymerization reactions. This explains the test results reported later, which show the effect on cations in relation to the acidity measured in the intercalate.

The proportion of free carboxyl groups can be increased by exposing the product to radiation capable of breaking the polymer molecules. Beta or gamma rays are suitable for this purpose.

For example, the compacted insert is subjected, in the presence of air, to gamma ray irradiation (Cobalt 60 source, 25 kGy). The radicals formed in the polymer material during irradiation react with the air to form, among other things, carboxyl anionic groups.

The content of carboxyl groups before and after irradiation is studied by acidity measurements, which are carried out according to the principle of acidity or alkalinity titration as specified in European Pharmacopoeia 8.6 for polyolefins. These measurements are performed by comparison with purified water, with heated water containing non-irradiated inserts, and with heated water containing irradiated inserts.

The results are presented in the following Table 1.

	Eau purifiée	Inserts non irradiés	Inserts irradiés
pH	6,8	5,5	5,0
Vh (ml)	1,2	1,5	2,4

The decrease in pH and the increase in the equivalent volume (Vh) at the color indicator's endpoint indicate the creation of a large number of acidic sites in the irradiated inserts, resulting in a significant increase compared to the case of copolymer inserts with non-irradiated carboxylic functional groups.

The remaining liquid that reaches the inner liquid reservoir in the bottle arrives sterile and free from biocidal cations. This is demonstrated by the following tests.

Sterility Test for Preserved Liquid

Tests were conducted to determine the amount of silver ions found in the closed space upstream of the membrane, in a first vial containing solution A and a second vial containing solution B, solutions described below. These solutions were found in the cut insert, divided along its length into three equal thickness sections forming the proximal part of the insert, the central part of the insert, and the distal part of the insert, as well as in the reserve solution, at different usage times of the vials corresponding to a volume of solution extracted from the vial through intermittent drop expulsions.

In these tests, two aqueous solutions known as eye drops are tested: a physiological solution A containing sodium chloride as the active ingredient in an aqueous medium, commonly used as eye drops in the treatment of dry eyes, and an ophthalmic solution B containing timolol maleate as the active ingredient in an aqueous medium, commonly used as eye drops in the treatment of glaucoma.

The results are presented in Table 2 for Solution A and in Table 3 for Solution B below. : Quantité d'ions argent en partie amont du conduit de circulation des fluides pour la solution A

Temps d'utilisation du flacon	Première utilisation	15 jours	30 jours	90 jours
Volume de solution A extrait	4 gouttes (0,15 ml)	1,67 ml	3,35 ml	10 ml (environ 300 gouttes)
En partie proximale de l'insert (ppm)	4,18	0,88	1,03	0,94
En partie centrale de l'insert (ppm)	1,75	0,56	0,44	0,61
En partie distale de l'insert (ppm)	0,81	0,26	0,31	0,22
Dans le réservoir (ppm)	< 0,001 ppm	< 0,001 ppm	< 0,001ppm	< 0,001 ppm

: Quantité d'ions argent en partie amont du conduit de circulation des fluides pour la solution B

Temps d'utilisation du flacon	Première utilisation	15 jours	30 jours	90 jours
Volume de solution B extrait	4 gouttes (0,15 ml)	1,08 ml	2,17 ml	6,5 ml (environ 200 gouttes)
En partie proximale de l'insert (ppm)	7,73	2,08	1,81	1,34
En partie centrale de l'insert (ppm)	4,95	1,36	0,91	0,63
En partie distale de l'insert (ppm)	1,08	0,36	0,42	0,27
Dans le réservoir (ppm)	< 0,001 ppm	< 0,001ppm	< 0,001 ppm	< 0,001ppm

The results of these tables 2 and 3 show that on one hand, silver ions are effectively retained in the insert, and on the other hand, the amount of silver ions retained in the insert decreases from the proximal part to the distal part of the insert. However, in the liquid reservoir, the amount of silver ions is below the detection limit (0.001 ppm).

Therefore, the liquid reserve is well protected from chemical contamination by biocidal cations.

The amount of silver cations retained in the insert is significant at first use, but tends to decrease during prolonged use of the bottle, without a sudden drop, indicating that a biocidal ion exchange movement occurs upstream of the membrane, between the membrane itself as the primary source of cations and the insert as the area for retention of biocidal cations carried by liquid backflow. The insert then becomes a secondary source of available biocidal cations that can be used during liquid sampling towards the membrane.

Forced Contamination Tests

Tests assessing the antimicrobial effectiveness of the device, through forced antimicrobial effectiveness tests and over time, are conducted first with a D1 device having an irradiated insert as described with reference to the figures, and second with a D2 device constructed like the D1 device except that the insert is not irradiated. These are compared with a D3 device whose insert is made of irradiated polyethylene, like the D1 device, but whose antimicrobial membrane is composed of the same base polymer material as that of the invention's device, but without any biocidal agent.

The forced biological contamination test consists of simulating the use of a vial by expelling droplets of liquid followed by inoculation of a given large quantity of contaminating germs. The number of germs found in a subsequently expelled droplet is then determined. The test results presented below in tables 4 and 5 were obtained following the following procedure. After putting into service a vial containing a sterile solution by expelling four drops of this solution, a large quantity of contaminating germs, here 105 (one hundred thousand) germs, are inoculated into the opening of the vial's nozzle. Then, the number of germs present in a drop of liquid expelled 6 hours (time T6) after the first inoculation is determined.The following day, that is, 24 hours after the vial was put into use, a drop of solution is extracted from the vial followed by an inoculation of 105 germs into the vial's nozzle. This procedure is performed three times during the day, once in the morning, once at noon, and once in the evening, to simulate the usual use of an eye drop. A drop of solution is extracted 24 hours (time T24) after the last inoculation, and the number of germs present in this drop is determined.

In addition, forced contamination tests are carried out on similar vials by first extracting drops of solution corresponding to a three-month usage period for a given solution. Then, the forced contamination protocol described above is applied by inoculating 10⁵ microorganisms into the opening of the nozzle, and a drop of solution is analyzed 6 hours later (at time T6). The next day, the extraction of a drop is performed followed by an inoculation, three times during the day. The number of microorganisms present in a drop extracted 24 hours after the last inoculation (time T24) is then determined.

The vials are tested with the physiological solution A and the ophthalmic solution B that were previously described for the examples in tables 2 and 3.

In these tests, two strains of aerobic contaminating bacteria were used: a P strain of Pseudomonas aeruginosa and an E strain of Escherichia coli.

The results are presented in the following tables 4 and 5: TABLEAU 4 : tests de contamination forcée avec la solution physiologique A

	Dispositif D1 Insert irradié		Dispositif D2 Insert non irradié		Dispositif D3 : Pas de cations Ag dans la membrane)		Durée d'utilisation du flacon
Temps analyse	T6	T24	T6	T24	T6	T24
Souche P	8	2	1 000	10	10 000	100 000	Immédiate
Souche P	<1	<1	1 000	10	10 000	100 000	A 3 mois (10 ml extraits)
Souche E	100	<1	10 000	100	100 000	100 000	Immédiate
Souche E	10	<1	10 000	100	100 000	100 000	A 3 mois (10 ml extraits)

TABLEAU 5 : tests de contamination forcée avec la solution ophtalmique B

	Dispositif D1 selon l'invention		Dispositif D2 comparatif avec insert non irradié		Dispositif D3 avec membrane non chargée initialement		Durée d'utilisation du flacon
Temps analyse	T6	T24	T6	T24	T6	T24
Souche P	<1	<1	1 000	10	100 000	100 000	Immédiate
Souche P	<1	<1	100	10	100 000	100 000	A 3 mois : (6,5 ml extraits)
Souche E	<1	<1	1 000	100	100 000	100 000	Immédiate
Souche E	<1	<1	1 000	10	100 000	100 000	A 3 mois (6,5 ml extraits)

The results of these tables 4 and 5 show the high efficiency of the distribution device according to the invention for maintaining the sterility of a liquid, which has been sterilized in reserve, during prolonged use in staged doses over time.

The results reported here are of interest in that they go beyond the normal usage conditions of eye drop bottles, showing that the microbiological quality of the liquid dispensed through the device of the invention remains acceptable even when artificially induced exceptionally high contamination has occurred. It follows that the same device of the invention can be used in applications involving much more severe contamination risk conditions, for example for products intended to be applied on wounds, burns, or on atopic skin in cosmetics, etc. The packaging of such products in multi-dose bottles thus becomes possible thanks to the invention. Moreover, it is clear that such results could not have been expected with previously known systems.

Trying with a viscous liquid

Forced contamination tests are carried out here to suit a viscous solution, by using a membrane with an average pore diameter significantly larger than 0.2 µm, chosen here as an example at 0.8 µm, which is much higher than the 0.2 µm porosity usually accepted for effective bacterial filtration.

A device according to the invention is tested, equipped with a membrane having an average pore diameter of 0.80 µm, used with a viscous solution V, in comparison with a device according to the invention equipped with a membrane having an average pore diameter of 0.22 µm, used with a less viscous solution T.

Both solutions are based on hyaluronic acid in different quantities, dissolved in buffer solution with a pH of approximately 7. For a total volume of 100 ml of aqueous solution, the viscous solution V contains 0.30 g of hyaluronic acid and has a viscosity of 60 mPa·s, whereas the less viscous solution T contains only 0.15 g of hyaluronic acid and has a viscosity of 3 mPa·s.

Forced contamination tests are carried out following the same protocol as previously described and using the same two contaminant bacterial strains, for immediate use of the vial and for simulated use over 3 months. The results are presented in Table 6 below.

These tests demonstrate the high effectiveness of the device according to the invention, based on a biocidal effect, over time in maintaining the sterility of the liquid in the vial, despite a significantly lower antibacterial efficiency through filtration. : tests de contamination avec les solutions T et V

	Dispositif selon l'invention avec membrane à 0,22 µm et solution T		Dispositif selon l'invention avec membrane à 0,80 µm et solution visqueuse V		Durée d'utilisation du flacon
Temps analyse	T6	T24	T6	T24
Souche P	<1	<1	<1	<1	Immédiate
Souche P	<1	<1	<1	<1	A 3 mois (27 ml extraits)
Souche E	2	<1	<1	<1	Immédiate
Souche E	2	<1	<1	<1	A 3 mois (27 ml extraits)

The above tests were conducted using a flask equipped with a liquid distribution head, in which, according to the invention, the initial ionic charge concentration in the membrane, in silver cations, is on the order of several thousand ppm. Of course, these are examples, which can be adapted by modifying the numerical values according to the practical conditions encountered in each specific application of the invention.

Continuation of the description of the figures

According to a particular implementation method of the invention, the capillary channel is drilled into a tip made from a material loaded with a biocidal agent, here also provided by a zeolite charge supporting ions. The capillary channel 18 is thus made in a dense polymer material tip, impermeable to liquid and air, loaded with silver cationic biocides that can move by migration from the mass to the surface. For example, the tip may be made of polyethylene loaded with a biocidal agent, notably with zeolites supporting silver cations.

A distribution head whose tip is thus charged with a biocidal agent, while the material forming the housing is not, is sufficiently described in the prior patent application WO2010/013131 of the Applicant, making it unnecessary to describe further details here.

To complete the description of the liquid distribution device in its application to a bottle, referring to figures 3 and 4, it should be noted that upstream of the membrane, in the wide portion of the fluid circulation channel shaped by the annular form of the housing 4, the free surface of the membrane is exposed. However, support fins 16, 17 are formed on the inside of the housing, to limit the stresses that may act on the edge of the membrane during operation, where it is bonded to a peripheral ring of the base of the nozzle provided with a capillary ejection channel for the liquid. However, these fins allow the membrane to bulge away from the base 3 of the nozzle.

Regarding the external side of the membrane as seen in its hydrophilic nature, the base 3 of the tip 5 forms a support surface for the membrane during the liquid expulsion phases, joining the wall of the capillary channel 18 at its flared opening 28.

Around this outlet, the free surface of the nozzle is grooved with radial grooves that provide a wide flow passage for the liquid near the membrane on the outside of the bottle. These radially arranged grooves 31 serve to collect the liquid exiting the bottle, guiding it toward the inlet of the capillary channel 18 after it has passed through the membrane in its hydrophilic area. However, their role is also to facilitate, during the air intake phase when the remaining liquid not expelled is re-sucked back into the bottle to compensate for the expelled liquid, that under the pressure of the air, the liquid is directed toward the hydrophilic area 22, thus freeing the central hydrophobic area 23 for the incoming air.

The surface of the base 3 also has corrugations that tend to finely divide any air flow originating from the exit of the capillary tube of the nozzle, which tends to reduce the speed at which it then passes through the membrane, even though the membrane is pushed away from the cross-sectional surface of the nozzle's base.

In the preferred form of realization of a nozzle as thus achieved according to the invention, particularly in the case of a dropper nozzle, the dividing corrugations for breaking up any circulating air stream are present in the form of relatively narrow and shallow grooves 32, hence of small cross-sectional passage, each being annular and arranged concentrically with respect to one another around the central capillary channel of the nozzle. These grooves 32 are cut into the surface of the nozzle base, in the sectors of the base protected by the liquid flow guide grooves 31, where the surface of the nozzle base is rather reserved to serve as a support for the membrane when it is pushed by the internal pressure of the compressed bottle to expel the liquid.

It is understood that, in operation, the specific configuration of the tip's surface facing the membrane plays a role in organizing fluid flow. This is not only because it promotes an alternation between liquid and gas flows within the central channel of the tip, but also because it guides the fluids along their return path, as shown by the arrows in Figure 4. The arrows f1 show that the residual liquid not expelled first is diverted from a direct axial path and directed toward the hydrophilic part of the membrane 22. Thus, it is prevented from being projected onto the central part of the membrane, where it would tend to wet the membrane material, which is hydrophobic in this area. The air flow drawn into the flask thus has free access to the hydrophobic material of the membrane in its central part 23, as illustrated by the arrows f2.

Returning now to Figure 1, completed by Figure 2, other details of the implementation of the liquid distribution head from a sterile packaging bottle can be observed. Although these are, in themselves, classical bottles manufactured industrially by the Applicant, they nevertheless constitute means that contribute to the implementation of the present invention through the quality of sterility preservation within the bottle.

In this context, it should be noted that the external peripheral ridges 15 of the housing 4 ensure a seal against bacteria with the neck of the bottle 10 at the level of the porous insert 8. It should also be noted that the design of the cap 6 is such that, when screwed (in 12) onto the neck of the bottle, it closes the external opening of the channel 18. Among other functions, it ensures a pressure drop downstream of the membrane, preventing it from being wetted by the liquid inside the bottle until the tamper-evident ring 26 has been broken for the first use (first expulsion of a drop of liquid).

In the same context, one should also note the shape of the capsule 8 at its upstream end, inside the bottle. Its utility will first be felt in applications intended for the distribution of eye drops with specific physico-chemical properties, such as surfactant or viscous characteristics. In such cases, the means illustrated will advantageously be used in combination with more specific embodiments of the invention, namely those providing a membrane with relatively coarse porosity leading to a lower level of microbial protection through filtration, while a high level of biocidal protection is achieved. These means consist of a configuration forming arches 13 around a central tablet 11 and arranged in the bottle 2 beyond its neck 10. They have been extensively described in the patent application WO 2011/095877. They contribute to a fluid flow organization that is favorable to the needs of the present invention in the case of the same liquids.

The test results mentioned above demonstrate an improvement in microbiological safety over time and in exposure to significant contamination, which could not have been expected from the mere use of a cationic biocidal membrane. They could not have been expected either from such a membrane that would additionally be partially hydrophilic and partially hydrophobic, since such a membrane alone could not ensure the alternation of liquid and air flow between the vial and the outside and vice versa.

In the case of the invention, this alternating flow is ensured because the partially hydrophilic and partially hydrophobic membrane, which forms the interface between the inside and outside of the container, is combined with a capillary channel for liquid expulsion and air intake located downstream of the membrane. It is also ensured in addition by other means that are known to control the alternation of flows under pressure effects, thereby ensuring the regularity and reproducibility of the transported masses and volumes.

Finally, if applying the ion-loaded antimicrobial membrane in a conventional bottle from the Applicant is already inventive by virtue of the role it plays in the transport of the active ingredient through the liquid backflow created during each dosing operation, it remains that the results demonstrated would not yet be achieved unless there was also added the presence of a porous insert serving as a non-airtight closure plug for the bottle, and optionally, as a flow regulator due to its porosity, which is conventional, but which in addition is made of a polymeric material containing anionic sites within its mass, having an attractive effect on metal cations, as is known, for example, with carboxylic sites.

Differences in ionic transfer behavior can actually be explained by considering that the membrane is a finely porous, relatively large-area structure across the fluid flow channel and has a small thickness, whereas the insert has a relatively coarse porosity and is thick, thus having a relatively long length along the fluid flow circuit. Also considering that, unlike the capillary channel on the downstream side, this insert occupies the neck of the flask over a relatively wide cross-sectional area, similar to the membrane.

Furthermore, whereas in the membrane, individual cells of the material are filled mostly either with liquid or with air, it will be observed that in the insert, both fluids are simultaneously present within the cells. Therefore, the oxygen from the air can affect the ionic charge transfers within the cells. The biocidal activity in destroying aerobic bacteria thus occurs differently than in the membrane's cells. Moreover, air and liquid come into contact with a large surface area of active material, corresponding to the specific surface area of the insert. The use of cationic charges in destroying bacteria is therefore even more effective.

And clearly, a similar effect cannot occur at the level of the circuit located downstream of the membrane, since there the material of the tip is dense and impermeable to both liquid and air. As a result, even if this material is initially based on an ion-containing polymer carrying silver ions, these ions must migrate toward the surface in order to become active on the fluids. The contact surface with the fluids at the tip is long but has a small perimeter around the capillary channel section. Moreover, it is alternatively exposed either to air or to water, including during the reflux of the remaining aqueous solution that was not expelled.

The differentiation of phenomena involving the transfer of ionic charges between the bifunctional interface membrane and the porous insert blocking the vial is all the more distinct when the fluid flow organization through them is better controlled, ensuring that the membrane remains dry in its hydrophobic area and that liquid backflow passes through its hydrophilic area. As long as the vial is in storage, before the first use consuming liquid, the membrane remains dry regardless of the vial's position, thanks to a pressure differential ensured on the downstream side by the hermetic sealing of the capillary channel; this pressure also exists upstream, thus keeping the membrane isolated from any contact with the porous insert.

In any case, it is a fact that between the two porous bodies, namely the membrane and the porous insert, a bed of mobile ions is formed during operation. These ions are extracted from the insert by the flow of liquid removed from the bottle during each distribution operation, starting from biocidal ions that were brought there by a return flow of undistributed liquid during previous liquid distribution operations. In practice, the biocidal ions thus remain confined to movements between the two porous bodies. Downstream of the membrane, the expelled liquid is not altered.

Without claiming to know the reality of the phenomena occurring at the molecular and ionic charge levels, one can consider a mechanism involving the availability of active sites directly accessible for contact with fluids on the surface of the polymeric material, taking into account the high specific surface area and the large void volume within the insert, as well as the thinness of the membrane. The membrane constitutes a primary source that has been sufficiently charged with a biocidal agent during manufacturing to be able to provide in abundance the amount of ions necessary to meet the needs of each application throughout the lifetime of the container until the initial liquid content is exhausted.The insert, in turn, is essential in the manufacturing process as a source of additional active sites for charge, complementary to those of the biocidal ions. Once the bottle has been opened for the first distribution operation, the insert sealing the bottle becomes active, both to protect the inner sterile space and to serve as a secondary biocidal agent. This agent retains the ions that have been introduced at the end of a distribution operation (air aspiration phase) until they are reused during a subsequent distribution operation. Those ions will then be carried by the liquid flow drawn from the bottle towards the membrane and retained there.except for those that have been consumed in passing by bacteria present in the air.

The high quality of sterility preservation observed during the forced contamination tests goes well beyond the specific needs for eye drop vials and other ophthalmic liquids, which are usually stored under protection of membranes that filter out external microorganisms. On the contrary, it shows that the invention's technique remains interesting as an alternative to conventional methods even in this case, whereas generally it will be useful in many application cases that do not require or do not allow a high level of bacterial filtration through the membrane. Furthermore, it is easy to understand that the implementation of the invention can be embodied in various forms suitable for large liquid capacities and long service lives in intermittent use, and/or for very diverse dosages and diffusion forms of the liquid expelled from the alternating fluid circulation channel, by simple dimensional adaptations of the essential components of the device according to the invention.

Claims (14)

1. Device for dispensing a sterile aqueous liquid, by doses spaced out over time, from a closed upstream space accommodating a liquid to an open downstream space via a capillary channel opening to ambient air, through an interface membrane, said device comprises an interface membrane produced to be partially hydrophilic and partially hydrophobic, in such a way that in operation, during each operation for dispensing a dose of liquid, the flows of air and of liquid circulate alternately in the capillary channel and a back flow of non-expelled remaining liquid takes place, characterized in that said interface membrane (7) is constituted by a filtration material the mass of which comprises biocidal metal cations, and in that said device comprises a porous insert (8), permeable both to liquid and to air, which is arranged upstream of the membrane on the path of the fluids and which is made of a material containing negatively charged sites capable of attracting biocidal metal cations originating from said membrane.
2. Device according to claim 1, characterized in that said biocidal metal cations comprise silver cations.
3. Device according to one of the preceding claims, characterized in that said biocidal metal cations of the membrane are supported by mineral macromolecules of the zeolite type incorporated in the mass of the base material of the membrane.
4. Device according to one of the preceding claims, characterized in that said negatively charged sites capable of attracting biocidal metal cations are anionic carboxyl groups.
5. Device according to one of claims 1 to 4, characterized in that said porous insert has a volumetric mass density comprised between 0.2 and 0.8 g.cm³.
6. Device according to one of the preceding claims, characterized in that said insert is based on a polyolefin polymer, preferably chosen from polyethylene, polypropylene, and the copolymers of ethylene or of polypropylene with up to 25% higher homologues of carboxylic acids or esters.
7. Device according to one of claims 1 to 6, characterized in that said insert is constituted by a compacted fibrous material.
8. Device according to one of the preceding claims, characterized in that said negatively charged sites capable of attracting biocidal metal cations result from irradiation of the porous insert with rays of the beta or gamma type in the presence of oxygen.
9. Device according to one of the preceding claims, characterized in that the material constituting said membrane has a pore diameter comprised between 0.1 and 1 micrometre.
10. Device according to claim 9, characterized in that the material constituting said membrane has an average pore diameter comprised between 0.4 and 0.8 micrometre.
11. Device according to one of the preceding claims, characterized in that said capillary channel is formed within a material incorporating biocidal metal cations, in particular borne by mineral macromolecules.
12. Sterile packaging bottle for an aqueous liquid to be dispensed in doses spaced out over time, by expulsion of a dose of liquid out of the bottle and entry of outside air in compensation, characterized in that it is equipped with a device for dispensing said liquid constituted according to one of claims 1 to 11, said insert (8) of which is mounted as a non-sealing closure of the inside of the bottle, said closed space then being inside the bottle.
13. Bottle according to claim 12, having a wall that can be reversibly elastically deformed, in order to ensure the entry of outside air compensating for any dose of liquid expelled from the bottle as well as the back flow through said device of any non-expelled remaining liquid, said membrane being mounted with said porous insert (8) in said device for dispensing liquid in combination with means of organization of the circulation of the air and liquid fluids through it, and in which said membrane is arranged at the base of a dropper tip within which is arranged the capillary channel (18) for the expulsion of the drops, opposite a base of said tip in which are arranged respective means for guiding the air aspired from the outside and any remaining liquid that has not been dispensed and is required to flow back to the downstream portion of the duct for the circulation of the fluids, which tend to direct the airflow to the hydrophobic part of the membrane preferably arranged in the centre of said membrane and to distribute the liquid over its hydrophilic part.
14. Bottle according to claim 12 or 13, in which said insert is intended to participate in the organization of the circulation of the fluids by constituting a flow regulator.