A comparative clinical trial of norinyl 1/35 versus brevicon in Rio Clara, Brazil

Abstract A comparative clinical trial of two combined oral contraceptives (OCs) with equivalent estrogen content, but different amounts of progestogens, was conducted at the Centro Medico Especializado em Planejamento Familiar in Rio Clara, Brazil. The study was designed to determine the differences in discontinuation rates between Norinyl 1/35 (Syntex) and Brevicon (Syntex) as well as the frequency of selected side effects which might contribute to method discontinuation. Both OCs contain 0.035 mg of ethinyl estradiol; Brevicon contains 0.5 mg and Norinyl 1/35 contains 1 mg norethindrone. Three-hundred women enrolled in the study were randomly assigned to either the Norinyl 1/35 or Brevicon OCs and follow-up visits were scheduled at 1, 4, 8 and 12 months after admission. Intermenstrual bleeding was reported by significantly more women in the Brevicon group than in the Norinyl group ( p The total discontinuation rates at 11 months for both groups were extremely high: 68.2 for the Norinyl 1/35 group and 75.2 for the Brevicon users. The largest group of discontinuations were comprised of those discontinuing for menstrual problems, other personal reasons, planned pregnancy and side effects.