Abstract

PIP: Since the introduction of oral contraceptives and IUDs there has been a decline in the use of other methods. In 1961 contraceptive aerosol foam was introduced and has become widely used. Vaginal contraceptives are reasonably effective; no systemic side-effects are produced; there are no medical contraindications and they can be used without medical supervision. Results of in vitro tests do not necessarily correlate with clinical effectiveness. To be effective a spermicide must be able to immobilize sperm immediately. It has been shown that aerosol foam and vaginal cream are quickly dispersed over the walls of the vagina and external cervical os. Jelly was not as well distributed. Material from vaginal suppositories was also poorly distributed. Pregnancy rates for the various preparations have ranged from 1.3 to 30 per 100 women years. The higher rates were usually associated with less reliable groups of patients. A great number of substances have been tested; of these phenylmercuric acetate and the surface acting agents (long-chain compounds, detergents, and soaps) are most widely used today. Urea in sodium carboxymethyl cellulose has been found to be effective and has been used in India. A number of chelating agents have spermicidal properties. For some compounds chelation with various metals reduces the spermicidal effect while for others the resulting chelates are more toxic than either substance alone. Heavy metals have not been used clinically in recent years. Metallic copper and metallic iron immobilize spermatozoa in vitro but a relatively large amount of the metals or their salts are needed. Patient acceptability is an important factor. Vaginal foam has been widely acceptable. All the preparations of vaginal spermicides have to be used near the time of coitus. Silastic rings have been intended only for the absorption of the steroid into the general circulation. To warrant commercial development, any new spermicides would have to have advantage over agents already in clinical use. A particular area of interest is vaginal preparations for both contraception and prophylaxis against veneral infections. No single product has yet been approved for both purposes although those currently used have varying degrees of activity in vitro against sexually transmitted pathogens. Irreversible inhibition of acrosomal protease (acrosin) has been investigated in the rabbit and 1 compound, tosyllysine chloromethyl ketone (TLCK), has an antifertility effect when applied vaginally in rabbits. Local immunization against sperm-coating protein or a sperm fraction has been tried in animals. The efficacy of non-spermicidal agents in humans would need to be determined entirely by results of clinical trials.