D-norgestrel: an estrogen-free, cyclic oral contraceptive.
In a pilot study, .5, 1, 1.5, and 2 mg doses D-norgestrel, an active isomer of norgestrel and twice as potent as the parent drug, were given in 4 groups of 25 patients each for a total of 833 cycles. All doses were virtually 100% effective in preventing conception. The 1 mg dose was found to be optimal with regard to side effects and cyclicity of bleeding. 1 mg doses were then given from Cycle Days 5 through 25. Patients were of proven fertility and in good health. An initial history, physical and pelvic examination, Papanicolaou smear, blood count, and urinalysis were taken on all and repeated at 6-month intervals. There were 334 patients for 5460 cycles or 455 woman-years. Menstrual irregularities were frequent, especially in the 1st few cycles. Return to normal menses within 1 month occurred in 95.5% after discontinuing therapy and in most of the remaining 4.5% within 2 months. To determine if ovulation was being suppressed, pregnanediol excretion, plasma progesterone, and endometrial biopsies were studied on selected patients. Data indicated an ovulation suppression effect from the 1 mg dosage. Abnormal Papanicolaou smears found in 3 instances before therapy later reverted to normal. As a result of missed pills, 2 patients conceived. Toxicity studies done on 20% of patients were norma l. Others have reported equally favorable results with D-norgestrel. A cceptability has depended on the patient's willingness to continue for at least 6 cycles, after which time undesirable symptoms usually diminish. Some patients become amenorrheic. This has not usually been an objection since the patient can be assured that she is not pregnant.