Is the vagina an adequate route for the administration of hormonal contraceptives?

The vaginal route of drug administration provides women with a valid alternative to more conventional methods of contraception. Drugs absorbed in the upper part of the vagina can bypass the liver and, if metabolized, are subject to a reduced hepatic first-pass effect. Current vaginally-administered contraceptive formulations deliver similar doses of gestagens to those provided by oral methods but release lower amounts of oestrogens. This results in a systemic exposure to gestagens similar to that achieved via other routes, thereby maintaining contraceptive efficacy while limiting systemic, but not uterine, exposure to oestrogen. In this way, the probability of systemic oestrogen-related adverse effects are theoretically reduced without compromising cycle control. In addition, the fact that the effects of a contraceptive ring last a complete cycle makes it more user-friendly than other methods and results in better patient compliance. The present review will explain in detail the specificities of this route of delivery of hormonal contraception and will compare it to more classic forms of contraception received via the oral (pill), intramuscular (injected), transdermic (patch) and subcutaneous (implants) routes of administration.