Medicine Drop Dispenser With Anti-Bacterial Filter

This invention relates generally to a medicine drop dispenser and more particularly to a squeeze-bottle type dispenser having a hydrophobic and microporous anti-bacterial filter secured over a dispensing outlet thereof.

Liquid dispensers of the squeeze-bottle type are utilized for dispensing medicinal solutions in droplet form. Conventional dispensers normally include a container composed of a resilient plastic material and a cap having a dispensing aperture formed therethrough. The liquid solution contained in the dispenser is commonly intermixed with a chemical disinfectant or preservative, such as thimerosal, that may induce an allergic reaction in a particular user. In addition, particulate matters suspended in the solution are generally dispensed with the droplets and may cause irritation in the eye of the user. Another problem encountered with conventional dispensers of this type is that bacteria may enter the container through the dispensing aperture to contaminate the liquid solution contained therein.

Although various attempts have been made to provide squeeze-bottle type dispensers with filters to prevent the ingress of bacteria and particulate matters therein, such dispensers have not fully solved the problems set forth above. U.S. Pat. No. 3,149,758, for example, discloses a squeeze-bottle type dispenser wherein hydrophilic and hydrophobic filters are secured within the cap of the dispenser in an attempt to filter out microorganisms and the like.

This invention overcomes the above briefly-described problems by providing a liquid dispenser comprising a container defining a liquid retaining chamber therein, a dispensing means defined at an upper end of the dispenser for providing the sole dispensing outlet from the chamber, and an anti-bacterial filter means secured over the dispensing means for providing a barrier to the ingress of bacteria and particulate matter therethrough and for permitting the egress of sterile liquid therethrough.

In one aspect of this invention, the filter means is entirely hydrophobic and microporous and is secured in exposed relationship over the dispensing means and further functions to repel residual liquid therefrom.

In another aspect of this invention, means are provided for inducing coalescence of dispensed liquid into droplet form, including a convex surface formed on the upper end of the dispenser and having the dispensing means defined therethrough and the filter means secured thereover.

In still another aspect of this invention, the dispensing means comprises a plurality of spaced ports formed through the convex surface of the dispenser and having a composite cross-sectional area approximating 1.0 mm.

In still another aspect of this invention, a cap is disposed on an upper end of the dispenser and the dispensing means includes a plurality of spaced ports formed through a centrally-disposed and convex outer surface of the cap.

In still another aspect of this invention, a detachable cap is mounted on the upper end of the dispenser and has a disinfectant pad therein that overlies, directly contacts and entirely covers the exposed filter means when the cap is in its closed position on the dispenser.

As described more fully hereinafter, the dispenser is preferably of the squeeze-bottle type, adapted to contain a liquid solution possessing curative or remedial properties, such as a saline solution or a medicinal solution having appropriate pharmacological additives intermixed therein. The filter is preferably hydrophobic to ensure that no residual solution remains on the outer surface of the filter means for potential contamination by ambient conditions. The repellent nature of the filter means will provide that even the last drop of liquid solution, falling back into the container, will be bacteria free. Thus, sterility of the solution will be maintained regardless of the number of times the solution is dispensed and no chemical disinfectant or preservative is required for the solution. The latter desideratum is important in respect to chemical disinfectants or preservatives that may cause an allergic reaction in a particular user.

Other objects and advantages of this invention will become apparent from the following description and accompanying drawings wherein:

FIG. 1 is an exploded, isometric view partially illustrating a liquid dispenser embodiment of the present invention;

FIG. 2 is an enlarged sectional view through an upper end of the dispenser;

FIG. 3 is a partially sectioned isometric view, similar to FIG. 1, but illustrating a second dispenser embodiment;

FIG. 4 is similar to FIG. 3, but illustrates a third dispenser embodiment;

FIGS. 5 and 6 illustrate a fourth dispenser embodiment; and

FIGS. 7 and 8 illustrate a fifth dispenser embodiment.

FIGS. 1 and 2 illustrate a liquid dispenser 10 of the squeeze-bottle type comprising a thin-walled plastic container 11 defining a liquid retaining chamber therein, terminating at an outlet passage 12. A fixed first cap 13 is secured on an upper end of the container, whereas a removable second cap 14 is detachably mounted on the container to cover the first cap. Container 11 is composed of a suitable resilient and squeezable plastic material, such as polyethylene, whereas the caps may be formed of a more rigid and non-squeezable standard plastic material.

As more clearly shown in FIG. 2, a dispensing means 15, shown in the form of a plurality of ports 16 formed through cap 13 at an upper end of the dispenser, provide the sole outlet for the liquid retained in chamber 12. A hydrophobic and microporous anti-bacterial filter 17 is secured on cap 13 and stretched over the ports to provide a barrier to the ingress of bacteria and particulate matter therethrough and to further provide sufficient porosity to permit the egress of sterile liquid therethrough for medicinal purposes. For example, the filter may be constructed in fabric form and composed of polycarbonate (with or without glass fiber reinforcement) to provide a pore size in the range of 0.2 micron. Standard filters of this type are manufactured by Nuclepore Co. of California.

The filter may be suitably secured to the outer surface of cap 13 by a conventional method, such as by molecular bonding using a brief exposure to acetone and pressure. The acetone should not, of course, cover the areas of the filter overlying ports 16. In fact, it is preferred that a circular surface area 18 defined within and between the circumferentially disposed ports (FIG. 1) remain unsecured to cap 13 for purposes hereinafter described.

It should be noted in FIGS. 1 and 2 that outer surface 18 of cap 13 is preferably convex, when viewed in cross section. This convex configuration at the apical of cap 13 in the area of ports 16 will induce the dispensed liquid to coalesce into a single droplet form when expelled from the dispenser upon inversion thereof and squeezing of container 11. Surface 18 may be formed semi-spherical, paraboloidal, hyperboloidal, or the like. Hereinafter-described dispenser embodiment 10d, illustrated in FIGS. 7 and 8, suggests that corresponding surface 18d and the overlying filter can be configured flat, but in no event concave.

Although FIG. 1 illustrates a single, centrally-disposed port 16 and eight circumferentially-disposed ports, it should be understood that the selected number and sizes of the ports will depend upon the particular dispensing application under consideration. It is desirable that the composite surface area of filter 17, covering ports 16, be sufficiently large to facilitate easy dispensing of the liquid, i.e., the force required to squeeze container 11 to force liquid through ports 16 and filter 17 to form a droplet decreases in proportion to an increase in the composite surface area of the filter covering the ports.

The maximum composite area of ports 16 will be determined to a large extent by the diameter of a standard dropper bottle and the cost of the filter material. For example, assuming that cap 13 and filter 17 are secured on the dispensing spout or neck of a standard dropper bottle having a standard 1 mm. dropper opening (e.g., similar to that shown in FIG. 3), the composite area of ports 16 would be greater than 1 mm., e.g., 0.5 mm. in diameter each. It should be further understood that the diameters of the ports could be varied in respect to each other to further induce the above-mentioned coalescence of liquid into single droplet form.

As more clearly shown in FIG. 2, cap 13 may be adhesively or otherwise suitably secured within an annular recess 19 formed at an upper end of the neck of container 11 to form an integral part thereof. If so desired, removable cap 14 may have a disinfectant-soaked pad 20 secured thereunder to engage and cover at least the portion of filter 17 overlying ports 16 during storage. The cap may be releasably attached to underlying cap 13 by any suitable means, such as an annular groove 21 formed interiorly of cap 14 and adapted to snap-fit upon flexing of the cap over a plurality of circumferentially-spaced lugs 22. Alternatively, outer cap 14 can be modified to extend downwardly into threaded engagement with threads formed on a lower portion of the neck of the container in a conventional manner (similar to that shown in FIG. 3).

FIG. 3 illustrates a second dispenser embodiment 10a wherein identical numerals depict corresponding constructions and wherein numerals appearing in FIG. 3 are each accompanied by an "a". Dispenser 10a is generally in the form of a standard dropper bottle and differs from dispenser 10 in that a filter 17a of larger diameter is stretched-over a semi-spherical surface 18a of a cap 13a and secured thereon by an elastomeric O-ring 23. An annular groove 24 is formed on the lower periphery of the cap to seat the O-ring therein. Threads 22a are formed on the dispenser to receive an internally threaded cap 14a of conventional design. A disinfectant pad (not shown), similar to pad 20, can be secured within cap 14a to overlie the filter when the cap is closed.

FIG. 4 illustrates a third dispenser embodiment 11b wherein corresponding constructions are depicted by identical numerals, but wherein numerals appearing in FIG. 4 are accompanied by a "b". This embodiment also resembles a standard dropper bottle comprising a squeezable plastic container 11b having a cap 14b removably mounted thereon by interengaging screw threads. A slightly convex filter 17b is stretched over a dispensing spout 13b of the dispenser and is secured thereon by a combined sealing and clamping ring 23b. The spout is preferably tapered in an upward direction (frusto-conical) along with the inner bore of the ring to provide a tight friction fit between the ring and the spout to clamp the filter therebetween.

A dispensing means 16b is defined at the termination of a single longitudinal dispensing passage 12b formed centrally of spout 13b. The dispensing means terminates at a convex surface 18b (when viewed in cross section) formed at the apical end of spout 13b to induce coalescence of the dispensed liquid into droplet form. The diameter of the standard dispensing passage approximates 1.0 mm. If so desired, a disinfectant pad (not shown) can also be secured within an upper end of cap 14b to overly passage 12b when the cap is in its closed position.

FIGS. 5 and 6 illustrate a fourth dispenser embodiment 10c wherein identical numerals, each accompanied by a "c", also depict corresponding constructions. A squeezable container 11b of the dispenser terminates at its upper end at a centrally-disposed spout 13c, having a single dispensing passage 12c formed centrally therein. The passage terminates at a dispensing means 16c. A filter 17c is stretched-over a convex outer surface 18c of the spout and is secured thereon by a combined sealing and clamping ring 23c.

The ring may be wedged and seated within a depressed annular groove 25, formed around the spout. An annular, flexible lip 26 may be formed on the container to overly the clamping ring to retain it in the position. In addition, the open annular area above the clamping ring and adjacent to the lip can be filled with a water-tight plastic adhesive (not shown) to fully seal this area and aid in retaining the clamping ring in place, if so desired. A conventional cap can be detachably mounted on spout 13c for storage purposes.

FIGS. 7 and 8 illustrate a fifth dispenser embodiment 10d wherein identical numerals, each accompanied by a "d", also depict corresponding constructions and components. The dispenser comprises a squeezable container 11c having screw threads 22d formed externally on its neck to threadably receive a cap 14d thereon. An annular spout 13d is formed integrally on the upper end of the neck of the container and defines the centrally-disposed dispensing passage 12d therethrough, terminating at a dispensing means 16d.

A round filter 17d is stretched-over the spout and port 16d and is clamped on the container by a combined sealing and clamping ring 23d, having an inside diameter suitably sized to frictionally engage and tightly lock the filter on the spout. An annular rib 27 may be formed on the underside of ring 23d to engage within an annular groove 25d formed on the container to precisely center the ring thereon. A suitable adhesive can be also utilized to aid in securing the ring on the container, if so desired.

From the above description, it can be seen that each of the various embodiments of applicants' invention includes an enclosure system for homogeneous liquids, such as a saline solution or medicinal drops, providing a barrier to the entry of bacteria and particulate matter, while yet allowing the user to dispense the sterile contents numerous times. The liquid solution, once packaged in the dispenser, will retain its sterility regardless of the number of times the solution is dispensed, without requiring the addition of chemical disinfectants or preservatives thereto. The dispenser will allow the economical packaging of large volumes of solution, while maintaining its sterility, which now necessitates expensive unit dose packaging. In addition, the enclosure system assures removal of particulate matter as the solution is dispensed. Utilization of disinfectant pad 20 will further aid in preventing bacterial growth, exteriorly of the dispenser in the area of its dispensing means.