Effect of oral contraceptives on plasma and platelet lipid composition. Influence of the length duration of time of ingestion.

The action of oral contraceptives (OC) (50 micrograms ethinylestradiol +250 micrograms levonorgestrel) on plasma and platelet lipid composition was studied in two groups of women who took this OC for one year, or for a longer period of time (2-9 years). Comparison with the control group showed that the ingestion of OC modifies the composition of some fatty acids in plasma and platelets. This modification is more marked in the women who took OC for one year. In plasma a decrease in linoleic acid (18:2) was found in the cholesterol and phospholipid fractions. In platelets, an increase of stearic acid (18:0) was observed in phospholipids, triglycerides and free fatty acid fractions. The modifications observed in plasma and platelets were not parallel, which suggests a specific and different action of OC on both plasma and platelets. Finally, it is suggested that the lipid variations found in the group that took the OC for one year may be compatible with a platelet hyperfunction.