Dydrogesterone to oppose the 100 mg oestradiol implant

Ten non-hysterectomised, post-menopausal women received the 100 mg oestradiol implant which was opposed by 20 mg dydrogesterone (nocte) for 14 days each 28-day cycle, for 6 cycles. Plasma oestradiol was measured at baseline and on three further occasions over 6 cycles. Endometrial biopsies were taken 5 weeks after implant, during the unopposed oestrogen and at week 24 during the progestogenic phase (sampling failed on both occasions in one patient). Secretory endometrium was seen in all women at the end of treatment. Cycle control was good and the mean day of onset of bleeding occurred on or after day 11 of the dydrogesterone dosage by the 5th cycle. Dydrogesterone 20 mg for 14 days every 28 days seemed to be sufficiently potent to counteract the proliferative effects of the high dose oestrogen implant.