Further experience with quingestanol acetate as a postcoital oral contraceptive

Abstract

A previous report based on investigations in Mexico suggested that quingestanol acetate might have potential as a postcoital oral contraceptive at a 800 mcg dose. This concept was based on some 1,000 cycles of therapy with no pregnancies in patients preselected to have 2 to 4 coital acts per week. Additional patients were then enrolled in this and two other centers. In the two new centers, patients were not preselected for frequency of intercourse. They accumulated some 3,400 cycles with a pregnancy rate of over 20 per 100 women years. The patients in the original center continued to take at least 2 to 4 doses the first two weeks regardless of coital frequency. They totaled some 5,500 cycles of experience with a 0.6 rate. The failure of the expanded studies in the general population was related to their coital frequency of only 8 per cycle. When doses of steroid were increased to 1.5 or 2.0 mg, the pregnancy rate declined considerably but the incidence of intermenstrual bleeding became unacceptable. These data indicated that the routine usage of the steroid as a postcoital contraceptive in the general patient population was probably not possible.