The effect of a biodegradable contraceptive capsule (Capronor) containing levonorgestrel on gonadotropin, estrogen, and progesterone levels.

Eight ovulatory women participated in the preliminary evaluation of a new method of contraception. The technique consisted of subdermal implantation of a biodegradable capsule capable of controlled release of levonorgestrel. The study spanned five menstrual cycles: three observation cycles to confirm ovulation, a cycle with the capsule implanted, and a follow-up observation cycle after its removal. All subjects who were sexually active relied on barrier contraception during the study. Basal body temperature determinations were made throughout all five cycles, and the last three cycles included serum assays of luteinizing hormone, follicle-stimulating hormone, estradiol, progesterone, and levonorgestrel on days 5, 8 to 18, and 22. All subjects except one experienced suppression of ovulation while the capsule was in place. No serious adverse effects were encountered. These results would seem to justify a larger clinical trial to assess the actual efficacy of this contraceptive method.