Co-administration of combined oral contraceptives and psychotropic drugs: risk of contraceptive failure and adverse events.

BACKGROUND

Combined oral contraceptives and psychotropic drugs are commonly used drugs in the female population. Yet, the quantity and quality of previous studies on drug interactions between these 2 medications are limited.

OBJECTIVE

To provide a detailed overview of the concomitant use of combined oral contraceptives and psychotropic drugs and its potential risk of contraceptive failure and adverse events in routine clinical practice.

STUDY

DESIGN

A pooled analysis of 4 large, prospective, multinational cohort studies comprising new users of combined oral contraceptives with and without concomitant psychotropic drug intake. We used exact matching (variable 1:10 ratio) on region, smoking status, age, and body mass index groups. Contraceptive failure and selected adverse events occurring within 6 months after combined oral contraceptive initiation were expressed by incidence rates per 100 women-years, crude, and adjusted Cox regression hazard ratios with 95% confidence intervals separately for Europe and the United States.

RESULTS

After matching, 8081 combined oral contraceptive+psychotropic drug users (Europe: 2271, United States: 5810) and 70,009 combined oral contraceptive-only users (Europe: 22,685, United States: 47,324) were considered for analysis. No substantial difference was found for the risk of contraceptive failure between combined oral contraceptive+psychotropic drug and combined oral contraceptive-only users. The hazard ratios adjusted for age, body mass index, medical history, oral contraceptive user status (ie, first-time ever user, switcher, restarter after intake break), and education level were 1.4 (95% confidence interval, 0.56-3.52) for Europe and 0.8 (95% confidence interval, 0.55-1.09) for the United States. The risk of adverse events was 1.5-fold higher in combined oral contraceptive+psychotropic drug users than in combined oral contraceptive-only users (Europe: 1.5 [95% confidence interval, 1.13-2.02]; United States: 1.5 [95% confidence interval, 1.22-1.88]). Most adverse events were related to the digestive and genitourinary systems.

CONCLUSION

No difference in the risk of contraceptive failure was found for combined oral contraceptive+psychotropic drug and combined oral contraceptive-only users, while combined oral contraceptive+psychotropic drug users tend to experience more adverse events.