Abstract:
A disinfectant cap for sterile liquid dispensers is disclosed. The cap for a dispenser for sterile liquid having a hollow container for storing the sterile liquid and a dispensing end having an outlet port, wherein the cap comprises a biocide-retaining element secured to the inner surface of the cap and is configured to contact the outlet port of the dispenser when in the closed position.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates to the field of dispensers for sterile liquids.  
       BACKGROUND  
       [0002]     Various ophthalmic and medical applications require a hand-held dispenser of multiple doses of sterile liquids. Sterile saline is required by contact lens wearers for use as a rinse solution, for rinsing the lens prior to inserting the lens in the eye, and also for soaking the lens during the cleaning and disinfecting process. Dispensers have been designed to maintain such liquids in a sterile state for dispensing, such as disclosed in the present inventor&#39;s U.S. Pat. No. 5,507,417, which discloses a dispenser for sterile saline solution and U.S. Pat. No. 6,745,763 which discloses a vaporizing device for administering sterile medication. Similarly, dispensers of medicinal liquids for eye, ear and nose drops desirably keep such liquids sterile between uses to prevent bacterial growth. An example of such device is disclosed in U.S. Pat. No. 4,533,068 Meierhoefer, wherein a hydrophobic filter is used to sterilize the replacement air which enters the dispenser upon release of the squeezing pressure. Other devices use an antibacterial hydrophobic filter over the outlet port, or hydrophobic and hydrophilic filters in tandem, to maintain the liquid sterile. See U.S. Pat. No. 3,149,758 Bush et al.; U.S. Pat. No. 4,938,389 Rossi et al. and Kramer et al. U.S. Pat. No. 4,463,880.  
         [0003]     Commonly such dispensers use a one-way valve or pump with a one-way valve to dispense the sterile liquid from a squeeze bottle or collapsible reservoir. A problem with existing devices is that after the sterile liquid is dispensed, some residue remains on the outlet port, or is drawn back into the outlet conduit, which can become contaminated with bacteria or the like and which will contaminate the next dose of the sterile liquid which is dispensed through the outlet port. There is therefore a need to avoid the foregoing problem with sterile liquid dispensers.  
       SUMMARY OF INVENTION  
       [0004]     The present invention provides a disinfectant cap for sterile liquid dispensers. The invention provides a cap for a dispenser for sterile liquid having a hollow container for storing the sterile liquid and a dispensing end having an outlet port, wherein the cap comprises a biocide-retaining element secured to the inner surface of the cap and is configured to contact the outlet port of the dispenser when in the closed position. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0005]     In drawings which disclose a preferred embodiment of the invention:  
         [0006]      FIG. 1  is a vertical cross section of a first embodiment of the invention with cap in the closed position;  
         [0007]      FIG. 2  is a vertical cross section of a second embodiment of the invention with cap in the open position;  
         [0008]      FIG. 3  is a vertical cross section of a third embodiment of the invention with cap in the closed position; and  
         [0009]      FIG. 4  is a vertical cross section of a fourth embodiment of the invention with cap in the closed position. 
     
    
     DESCRIPTION  
       [0010]     Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.  
         [0011]     With reference to  FIG. 1 , a hollow container  10  contains sterile liquid  12 . Typically the container  10  will be constructed of a flexible plastic such as polyethylene to permit squeezing or collapse of the container. Cap  14  is preferably formed of a rigid plastic material. Cap  14  is sized to provide a friction or snap fit, or threaded connection over neck  18  of container  10 . Container  10  has a liquid-dispensing tip  20  having a central outlet conduit  22  communicating with outlet opening  24 . Sterile liquid is dispensed by inverting and squeezing the container  10 .  
         [0012]     The interior of container  10  communicates with outlet conduit  22  via communication port  15 . To preserve the sterility of sterile liquid  12  when the liquid is dispensed from container  12  such as by squeezing the container, a filter assembly comprising hydrophobic filter  26 , hydrophilic filter  28  and support discs  33  is provided across the liquid passage from port  15  to outlet  24 . Filters of the type disclosed in U.S. Pat. No. 4,938,389 are suitable or other suitable microporous filters known in the art. Cap  14  is also provided with a biocide-containing pad  30  which is fixed to the upper inner surface  32  of cap  14  by adhesive or the like. The pad  30  may be a biocidal-powder impregnated pad or may be formed of absorbent material such as sponge or absorbent cotton material which soaks up a concentrated liquid biocide stored in hollow cavity  34  in cap  14  and wicked to pad  30  by wick  36  (see  FIG. 2 ). In the embodiment shown in  FIG. 1 , preferably pad  30  extends partly or completely down conduit  22 .  
         [0013]      FIG. 2  illustrates a second embodiment of the invention wherein a one-way valve  25  prevents the egress of contaminants into the squeeze bottle  10 . Valve  25  has a conduit  27  and a small hole  29  at the dispensing port formed in a rubber material under tension whereby the hole is normally closed but opens when pressure increases in conduit  27 . By squeezing bottle  10 , sterile liquid  12  is forced into conduit  27 , hole  29  opens and the liquid  12  is dispensed. When cap  14  is replaced, pad  30  completely covers the dispensing tip  29  to sterilize any remaining liquid on the exterior. Container  10  remains collapsed after liquid is dispensed as no air is permitted back into the container.  
         [0014]     An alternate form of biocidal pad is indicated at  48  in  FIG. 3 . In this case the pad is resilient and conical in shape to conform to fill the space between surface  21  of the tip  20  and the inner surface  32  of cap  14 . The inner surface  32  of cap  14  may have an inwardly projecting bump or thickening  40  in the region of the hole  29  in order to compress the pad  48  against the tip  20  in that region. Again pad  48  can be either impregnated with a biocidal powder, or liquid-absorbent and wicked to a supply of concentrated liquid biocide. In this embodiment a one-way valve  25  is provided again, with dispensing hole  29 . A secondary hinged one-way valve  36  is provided made of a resilient rubber material or the like. Tip  20  is formed of a squeezable material such as rubber. Sterile liquid  12  flows into chamber  22  such as by inverting container  10 . By squeezing tip  20  the valve  36  closes and liquid is forced through dispensing hole  29 . After dispensing, cap  14  is replaced so that pad  48  is compressed against the tip in the region of hole  29 , thereby placing biocide in contact with the entire surface  21  of tip  20 . By forming pad  48  of compressible sponge material, the pad may expand when the cap is removed and when screwed into position will scour the surface  21  in the region of hole  29  as well as the entire tip  20 .  
         [0015]     A further alternate form of disinfectant cap  14  is shown in  FIG. 4 . In this case the tip  44  has a sharp conical outlet end  46  and one-way valve  45 . A body of biocide  47 , such as a gel or liquid, is retained by membrane  50  in the upper portion of cap  14 . When cap  14  is closed, the end  46  pierces a central opening in membrane  50  and is immersed in the gel biocide  47 . Membrane  50  is formed of rubber or the like so that when end  46  is withdrawn from the central hole the hole is closed by surface tension to retain the biocide gel within the membrane.  
         [0016]     As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.