Comparative study of the effects of two once-a-month injectable steroidal contraceptives (Mesigyna and Cyclofem) on lipid and lipoprotein metabolism. United Nations Development Programme/United Nations Population Fund/World Health Organization/World Bank, Special Programme of Research, Development and Research Training in Human Reproduction.

A 1-year longitudinal multicenter study was undertaken to monitor the effects on lipid metabolism of two once-a-month injectable contraceptive preparations, Mesigyna (50 mg norethisterone enanthate and 5 mg estradiol valerate and Cyclofem (25 mg medroxyprogesterone acetate and 5 mg estradiol cypionate). A total of 357 volunteers from four centers (Hangzhou, Havana, Jakarta, and Shanghai) were monitored during one pretreatment cycle, the third and ninth injection intervals, and during one post-treatment cycle, approximately 3 months after the 9-month period of treatment was completed. With both preparations, changes were observed at 3 months of use, remained essentially unchanged during treatment, and returned to pretreatment levels after discontinuation of use. With Mesigyna, changes consisted mostly of decreases in high density lipoprotein cholesterol (HDL-C, -10%), apolipoprotein AI (-9%), and triglycerides (-15%). With Cyclofem, changes were even smaller. With both, variations in lipid levels mirrored closely the pharmacokinetics of each preparation and the biphasic nature of the injection intervals.