Effects of adding C-19 versus C-21 progestin to conjugated estrogen in moderately hypercholesterolemic postmenopausal women.

Abstract

Our purpose was to compare the effects on fasting plasma lipoprotein lipids of adding low dosage C-19 continuous progestin (dl-norgestrel) versus conventional low-dosage continuous C-21 progestin (medroxyprogesterone acetate) to cyclic conjugated estrogen therapy. Nine hypercholesterolemic postmenopausal women with intact uteri were randomly assigned in a prospective, double-blind, two-period crossover study of conjugated estrogen plus either (1) dl-norgestrel (0.05 mg/day) or (2) medroxyprogesterone acetate (2.5 mg/day) for 1 year and after an appropriate washout period were switched to the alternative regimen for another year. Four subjects received conjugated estrogen only. Compared with baselines, each of the C-19 and C-21 progestin regimens significantly increased plasma high-density lipoprotein cholesterol (15% vs 12%) and reduced the ratio of total cholesterol/high-density lipoprotein cholesterol (20% vs 15%, respectively), but only the former significantly reduced plasma triglycerides (24% vs 0.3%, p < 0.05). Low dosages of either dl-norgestrel (C-19) or medroxyprogesterone acetate (C-21) when combined with conjugated estrogen significantly improve plasma lipoprotein lipids of postmenopausal women.