St John's wort extract (Ze 117) does not alter the pharmacokinetics of a low-dose oral contraceptive

St John's wort (Hypericum perforatum) is an herbal remedy that is widely used in the treatment of depression. Recent clinical data have demonstrated that St John's wort extracts interfere with the action of various drugs and possibly also with combined oral contraceptives. Therefore, we investigated the effects of a St John's wort extract (Ze 117) with low hyperforin content on the pharmacokinetics of ethinylestradiol and 3-ketodesogestrel.

Sixteen healthy female volunteers, who had taken a low-dose oral contraceptive (Lovelle contains 0.02 mg ethinylestradiol + 0.15 mg desogestrel) for at least 3 months, participated in the study. Pharmacokinetic data (AUC, C(max), t(max)) were determined the day before (reference) and after (test) a 14-day period of Ze 117 intake (250 mg twice daily).

Before the co-administration of Ze 117 on day 7, the geometric mean (geometric coefficient of variation) for the AUC(0-24) of ethinylestradiol was 152.53 pg.h/ml (87.39%) and after co-administration on day 21 it was 196.57 pg.h/ml (78.14%). The respective values for ketodesogestrel were 36.37 pg.h/ml (34.18%) and 41.12 pg.h/ml (34.36%). The mean of individual ratios (reference-to-test) of log-transformed AUC values (90% confidence interval) were 0.951 (0.915-0.986) for ethinylestradiol and 0.968 (0.944-0.992) for ketodesogestrel indicating a small gain [corrected] in bioavilability, but bioequivalence nevertheless.

These results indicate that the recommended dose of the hypericum extract Ze117, which has a low hyperforin content, does not interact with the pharmacokinetics of the hormonal components of the low-dose oral contraceptive.