The effects of the addition of nomegestrol acetate to post-menopausal oestrogen therapy

Abstract

Progestogens are added to the oestrogen treatment for 10-12 days each cycle in order to prevent endometrial abnormalities. However, concern has been expressed about the safety of certain of the currently available progestogens because of the potential adverse metabolic effects. We have evaluated the effects of nomegestrol acetate - non-androgenic progestogen - for administration to post-menopausal oestrogen users. Thirty-six (36) women receiving 50 mg oestradiol implants at regular intervals also took nomegestrol acetate for 12 days each calendar month at doses of 0.5 mg, 1.0 mg and 2.5 mg daily. Allocation to one of the dose regimens was random. Physical and psychological side-effects were recorded and all vaginal bleeding was noted: an endometrial biopsy was performed on the sixth day of progestogen addition for histological, ultrastructural and biochemical evaluation. Adverse side-effects were responsible for a dose-dependent drop out rates of 17%. All patients experienced a regular, progestogen-induced withdrawal bleed each month; and histological, ultrastructural and biochemical changes were induced within the endometrium by all 3 doses. Nomegestrol acetate is a potent progestogen and further studies are required to determine its lowest effective dose.