[New approaches to interception--postcoital use of a gestagen/estrogen combination]

Postcoital application of high doses of ethenyloestradiol (EE) over a period of 5-6 days can, in the majority of cases, prevent pregnancy if therapy is initiated early enough (failure rate 1%), but such doses are attended by a high rate of side effects. Yuzpe et al. have tested an alternative formulation for interception: in a series of studies conducted in Canada and USA they administered a total dose of only 0.2 mg EE in combination with 2.0 mg DL-norgestrel (potency equivalent to a dose of 1.0 mg D-norgestrel) which was given in 2 portions separated by a 12-hour interval. The results of these studies and, in particular, those of a double-blind study (high doses of EE versus EE/norgestrel combination) in the Netherlands appear to indicate that the interceptive efficacy of the oestrogen-gestagen combination is equivalent to that of the high-dose oestrogen formulation. Distinct advantages are: the much lower active substance content, the shorter period of therapy (12 hours as opposed to 5 days), which is important as regards patient compliance, the limited duration of concomitant gastro-intestinal effects which can no longer be responsible for premature termination of therapy, the absence of breast tension and menstrual disorders. However, even application of the new method, which is facilitated by the commercial preparation Tetragynon, is intended for emergencies only.