1. Field of the Invention
This invention relates to an improved intravaginal contraceptive barrier that permits additional versatile protection against sexually transmitted disease.
2. Description of the Prior Art
Cervical caps have been used since 1350 B.C. to prevent pregnacy. Egyptians used hollowed out lemons cut in half for this purpose and squeezed out some of the juice to act as spermicide. Since the invention of latex in the 1920's, vaginal diaphragms have been used for the same purpose. In recent years, "spermicides", such as Nonoxynol-9, have been used as adjuncts to increase the efficiency of diaphragms in preventing pregnancy, as well as sexually transmitted diseases. Nonoxynol-9 (U.S. Pat. No. 2,313,477), in low non-toxic, non-cytocidal concentrations, not only increases the effectiveness of diagragms in preventing pregnancy, but also has been found to prevent cell to cell infection with AIDS viruses carried by migrant lymphocytes in semen and in endocervical secretions.
Dunn et al (U.S. Pat. No. 4,589,880) reviews the various diaphragms currently in commercial use and claims a disposable spermicide-releasing diaphragm and cervical cap. The spermicide, Nonoxynol-9, is released in situ by diffusion when a water soluble polymer matrix dissolves. The device consists of a thermoplastic elastomer such as a polyether-polyurethane that has been blended homogeneously with Nonoxynol-9, and a water soluble polymer such as polyethylene glycol. The Nonoxynol-9 and the water soluble polymer migrate to the surface of the device by diffusion and are released into the vagina at a controlled rate upon contact with vaginal fluid. The spermicide is released randomly from the surface of the device and is distributed more or less homogeneously throughout the vagina.
It is now known that the most probable place for the AIDS virus (HIV) to enter a femal upon contact with infected semen is in the vicinity of the external OS of the cervix uteri. Only on the endocervix is the epithelium thin enough to permit passage of an infected lymhocyte. Thus, the Dunn device would not concentrate Nonoxynol-9 in the area where it would be the most effective in protecting the woman against infection by HIV. In addition, the device would not be useful for women allergic or sensitive to polyurethane. Finally, the device is expected to be expensive on a per-use basis inasmuch as it is not reusable.
Gutnick, in U.S. Pat. No. 4,332,243, teaches the use of a burstable medication-releasing well in the wall of a condom or diaphragm. Gutnick's device depends upon the rupture of a partitioning membrane on the well to release medicament and is, therefore, non-reusable. Moreover, it is unclear how such a well could be refilled by a user even if such a device was reusable.
U.S. Pat. Nos. 4,332,243 and 4,393,871 describe methods for dispersing spermicides from receptacles, such as polyethylene sponges, but provide no stable anchoring mechanisms for holding such receptacles in place near the opening of the female cervix. The contraceptive sponge, although molded as if to fit the cervix, seems to wander and often turn upside/down. The concept of Loeb-Perry, using a 1 1/2inch diameter, nonoxynol-impregnated, disposable "Diaphragm Disk" with an adhesive coating on one side sounds attractive, but it is not certain how long as latex diaphragm will be tolerant of repeated applications of the adhesive before developing leaks.
There is a clear need for a reusable intravaginal device that is effective as a contraceptive, non-allergenic, easy to insert and remove, easy to clean and, most important, capable of delivering repeated doses of a spermicide such as Nonoxynol-9 or antimicrobial agent in concentrations sufficient to prevent sperm or virus-laden cells that have penetrated the contraceptive barrier from entering the cervix.
This invention relates to an improved design for vaginal diaphragms and cervical caps. The improved diaphragm or cervical cap has either an integral pad-retaining member or pouch shaped to hold a foam pad which releases a solution containing various forms of spermostatic/lymphocytostatic chemicals directly over the vaginal opening of the female uterine cervix where their dispersion under the pumping action of sexual intercourse will be optimally effective in preventing pregnancy, as well as sexually transmitted diseases, especially virus infections carried by migrant lymphocytes. Both the pad-retaining members and pouches are designed to hold a foam pad which will gradually dispense chemicals in solution from the saturated foam pad during intercourse. The choice of pad-retainer or pouch molded into the diaphragm or cervical cap is determined by the need to control chemical dispersion from the foam pad housed within the pad-retainer or pounch will, therefor, depend on the medication being dispensed and the size and shape of the foam pad. The specifications are adaptable to standard diaphragms and cervical caps made of latex or silicone.