The Efficacy and Safety of an Oral Contraceptive Containing Chlormadinone Acetate: Results of a Pooled Analysis of Noninterventional Trials in Adult and Adolescent Women

Background: The study was conducted to assess the contraceptive efficacy, cycle events, dysmenorrhea symptoms and skin complaints of a combined oral contraceptive containing 2 mg chlormadinone acetate/0.03 mg ethinylestradiol (CMA/EE) (Belara®, Grünenthal GmbH, Aachen, Germany) in adolescent and adult women using a conventional- or extended-cycle regimen.

Study Design: Data were pooled from six noninterventional trials with CMA/EE intake over 4-12 cycles.

Results: The data pool contained 62,218 women (345,964 cycles), of whom 60,508 were analyzed (325,937.5 cycles), including 46,335 adults, 13,478 adolescents and 695 age unknown; 1710 retrospective documented patients were excluded from analysis. A total of 85 women became pregnant (including women missing pills) on the conventional-cycle regimen (21+7), giving a practical Pearl index of 0.34 [95% confidence interval (CI) 0.27-0.42]. Within this group (n=85), there were 19 pregnancies associated with regular pill intake, which represent a theoretical Pearl index of 0.08 (95% CI 0.05-0.12) per 100 women-years. Overall, cycle stability, bleeding profile, dysmenorrhea and the incidence of seborrhea/acne improved with CMA/EE, and there was no clinically relevant change in body weight or body mass index. Six venous thromboembolic events were reported, equating to an incidence of 2.4 per 10,000 women-years.

Conclusions: Chlormadinone acetate/ethinylestradiol is effective and well tolerated in adolescent and adult women.