Effect on lipid metabolism of a biphasic desogestrel-containing oral contraceptive: divergent changes in apolipoprotein B and E and transitory decrease in Lp(a) levels.

The effect of a low dose biphasic oral contraceptive containing 40 micrograms ethinylestradiol + 25 micrograms desogestrel (7 tablets) and 30 micrograms ethinylestradiol + 125 micrograms desogestrel (15 tablets) on lipid metabolism was investigated in 19 women during 6 cycles of treatment and compared to the values of the pre- and post-treatment cycle. During treatment, all components of HDL increased reversibly by 10 to 30%. The levels of total cholesterol (CH), LDL-CH and IDL-CH rose only slightly, while those of total triglycerides (TG), VLDL-TG and LDL-TG rose continuously by more than 100% until the 6th cycle. At the same time, plasma levels of VLDL-CH increased by 60% and of apolipoprotein B by 20%. Contrary to this, apolipoprotein E decreased by 25% during treatment, and Lp(a) was transitorily reduced during the 3rd cycle. After termination of intake, total CH, LDL-CH, IDL-CH and apolipoprotein B remained elevated, while total TG, VLDL-TG, VLDL-CH and LDL-TG decreased significantly, but were still elevated during the post-treatment cycle. The levels of apolipoprotein E returned to pre-treatment values. The results indicate a marked preponderance of the effect of the estrogen component. The rise in TG and VLDL synthesis seems to be outweighed by an enhanced removal of apolipoprotein E-containing remnants which might offer protection from the development of atherosclerosis.