State-of-the-art of non-hormonal methods of contraception: II. Chemical barrier contraceptives

Chemical contraceptives mainly known as spermicides are one of the oldest types of contraceptives. The industrial revolution facilitated new developments, and they became a leading and widespread method. However, their use declined in the second half of the 20th century, and came under focus again only with the upsurge of sexually transmitted infections (STIs). The effectiveness of spermicides depends on the users' compliance and pregnancy rates vary widely: from 6/100 woman-year (with perfect use) to 26/100 woman-year (with typical use). Preparations consist of two components: an excipient (foam, cream, jelly, soluble film, suppository or tablet); and a chemical agent with spermicidal properties (acidic compound, microbicidal agent, detergent). The most widely used active agent has been the surface active (detergent) nonoxynol-9 (N-9). Based on their mode of action (surfactant effect of detergents, enzymatic action of microbicides on cell metabolism) spermicides were thought to provide protection against STIs including HIV. Recent studies have, however, shown that detergents may actually increase the risk. Because of this, there is an urgent need for a suitable non-detergent spermicide, and research should focus on developing new compounds to replace N-9 and other agents having similar undesired effects. This paper reviews the latest studies reporting results on these recent developments.