Metabolic effects of oral contraceptives containing 30 micrograms and 50 micrograms of oestrogen.

In Study A, biochemical data from 17 women who were not taking oral contraceptives were compared with those from women taking preparations which contained either 30 microgram of ethinyl oestradiol and 150 microgram of D-norgestrel (18 women) or 50 microgram of ethinyl oestradiol and 250 microgram of D-norgestrel (nine women). In Study B, biochemical data were collected from eight women before and during the first three or four months therapy with preparations containing 30 microgram of ethinyl oestradiol and 150 microgram of D-norgestrel. The two oral contraceptive dosage forms studied produced qualitatively and quantitatively similar metabolic changes. Both caused an increase in serum concentration of triglycerides (30% to 33%), beta-lipoproteins (27% to 29%) and ceruloplasmin (75% to 90%), and a decrease in serum levels of antithrombin III (22% to 29%) and ascorbic acid (30% to 42%). Serum cholesterol and phospholipid concentrations were unchanged. However, the proportion of serum cholesterol carried by alpha-lipoproteins (high density lipoproteins) decreased, while that carried by beta-lipoproteins (low density and very low density lipoproteins) increased. The former change is in the same direction, but much smaller than that observed in coronary heart disease.