Prostaglandin production in human endometrium following continuous exposure to low-dose levonorgestrel released from a vaginal ring

Arachidonic acid metabolites produced by primary cultures of human endometrial cells derived from biopsies obtained before and after exposure to 20μg/day levonorgestrel for 84 ± 1 days were analysed by reverse phase HPLC. This revealed a significant increase in PGF 1α and an epoxide metabolite upon levonorgestrel stimulation. The proportion of epoxide metabolite, PGF1α and PGE2 were positively correlated with serum levonorgestrel levels while HETES, PGE2 and epoxide were similarly correlated with serum oestradiol. The extent of intermenstrual bleeding during exposure to levonogestrel was correlated with the proportion of epoxide and HETES products in vitro which is discussed in relation to their physiological function.