Influence of a triphasic oral contraceptive preparation on plasma lipids and lipoproteins.

The influence of a triphasic oral contraceptive preparation on plasma lipid, lipoprotein, and apolipoprotein levels was studied in 20 women during 12 treatment cycles. Multiple blood samples representing all phases of the therapeutic cycle as well as posttherapy were obtained. Total and low-density lipoprotein (LDL) cholesterol fluctuated transiently in the earlier part of the study but after 9 and 12 cycles of therapy did not differ from baseline. Cyclic elevations in total cholesterol corresponding to changes in LDL cholesterol were noted twice. Total high-density lipoprotein (HDL) cholesterol remained remarkably stable over the entire study while HDL2 cholesterol decreased and HDL3 cholesterol increased. Triglycerides (total and lipoprotein fractions) increased during treatment and fell to baseline levels within one posttreatment cycle. Very low-density lipoprotein (VLDL) cholesterol was also elevated during the study. Apolipoprotein (apo) AI, apo AII, and apo B rose under therapy, the latter increase producing a lowered LDL cholesterol/apo B ratio. Apolipoprotein E showed a temporary decrease early in the study but otherwise remained unchanged.