Loss of Oral Contraceptive Efficacy by Concurrent Antibiotic Administration

Abstract

There are approximately 10 million women in the United States who are currently taking oral contraceptives on a daily basis. Although the actual number is not known, it is also estimated that a large number of these same women are on concomitant drug therapy. In recent years there have been a number of published reports linking a loss of contraceptive efficacy with the concurrent administration of other drugs, including antibiotics. Whereas the actual risk of drug interaction between antibiotics and oral contraceptives is yet unknown, it is important that women who are on oral contraceptive therapy be aware of possible contraceptive failure. This article reviews the published incidence of oral contraceptive/antibiotic interaction, along with a discussion of the possible mechanisms by which this interaction occurs. Recommendations are also presented for the health management of women taking oral contraceptives and other prescribed drugs.

Antibiotics, the pill, and pregnancy.

“…rere treated 0 An information leaflet could be drawn up nsultations and given to all women known to be on the roat condi-OCP and for whom antibiotics are prescribed. ribed anti-A sample leaflet is shown in fig 3 and is based with other on existing information leaflets given out in g a further family planning clinics in Buckinghamshire. Your doctor has prescribed you antibiotics which are necessary to treat the infection.…”

“…In addition, high concentrations of oestrogens and progestins produce alterations in the genital tract and endometrium that may contribute to the contraceptive effectiveness of these preparations. 3 Although more than 85% of couples who are sexually active claim to be using some method of contraception, it is known that up to one third of pregnancies can be unplanned. The failure rate of the OCP is very small, between 0-1 %4 and is often attributed to one of the following: * Patient forgetting to take the OCP.…”