Hormonal Emergency Contraception

Melissa Sanders Wanner, Pharm.D., Rachel L. Couchenour, Pharm.D.

Disclosures

Pharmacotherapy. 2002;22(1) 

In This Article

Danazol

Danazol is an antigonadotropin that works primarily by disrupting ovulation.[16] When administered to women during the follicular phase, it inhibits or delays the peak in luteinizing hormone, thereby suppressing or delaying ovulation.[16,38] It is unclear if danazol has a direct effect on the endometrium when administered during this time in the menstrual cycle. Postovulatory administration does not affect ovarian function or endometrial development. The absence of effects during the luteal phase in part may explain the inconsistent effectiveness observed with danazol.[16]

Danazol was investigated in the early 1980s as an emergency contraceptive in an attempt to identify an agent that was as effective as the Yuzpe method but caused fewer adverse effects.[38] The authors of one study[9] compared two danazol regimens with the Yuzpe regimen in 2339 women seeking emergency contraception. The first dose of each therapy was initiated within 72 hours of unprotected intercourse. Women were included if they had one act of unprotected intercourse within the past 72 hours, only one act of intercourse in the past month, and regular menstrual cycles. Among the 2127 women who attended a 4-week follow-up visit, 990 had received 2 doses of danazol 400 mg given 12 hours apart, 730 women had received 3 doses of danazol 400 mg given at 12-hour intervals, and the remaining 407 women had received the Yuzpe regimen. The pregnancy rates were 1.7% in the danazol 800-mg group, 0.82% in the danazol 1200-mg group, and 2.2% the Yuzpe group. In the danazol 800-mg, danazol 1200-mg, and Yuzpe groups, 73%, 86%, and 69% of expected pregnancies were prevented, respectively. The differences among the three groups were not statistically significant.

In a second study,[8] the effectiveness of danazol 600 mg given within 72 hours of unprotected intercourse and 600 mg given 12 hours later to 193 women was compared with that of the Yuzpe regimen in 191 women. Women were eligible for the study if they had only a single act of unprotected intercourse during their present cycle, presented within 72 hours of the act, and had regular menstrual cycles. The raw pregnancy rate was 4.66% (9 pregnancies) in the danazol group, and 11 pregnancies were expected (difference was not significant). There was no difference between the number of observed pregnancies and the number expected, suggesting that danazol may be ineffective for emergency contraception. Among women assigned to the Yuzpe regimen, 2.6% became pregnant (5 pregnancies) and 11 pregnancies were expected. The authors reported that this 55% reduction in the number of expected pregnancies was statistically significant; however, the reported p value was 0.061. Although there appeared to be a difference in raw pregnancy rates between danazol and the Yuzpe regimen, this difference did not reach statistical significance.

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