Changes in serum lipoproteins and high-density lipoprotein composition during isotretinoin therapy.

Oral isotretinoin has been reported to increase serum total triglycerides (TG), cholesterol (TC), phospholipids (TPL), apoprotein B (apo B), and to reduce high-density lipoprotein cholesterol (HDL-C). To investigate the effects of isotretinoin on HDL, we measured HDL-C, HDL phospholipids (HDL-PL), apoprotein A1 (apo A-1), and HDL-C subfractions (HDL2-C and HDL3-C) in 24 healthy, male patients receiving a 16-week course of isotretinoin (1.0 mg/kg/day) for treatment of severe acne vulgaris. Patients were placed on a constant diet and fasting lipid parameters were measured every 4 weeks. Analysis of the data from the 20 patients who completed the study confirmed the reported increase in TG, TC, LDL-C, apo B, and LDL-C/HDL-C (all p less than 0.01) observed during isotretinoin therapy. Reduction occurred in HDL-C (p less than 0.05) and HDL2-C (p less than 0.01) while HDL3-C remained unchanged, indicating that the effect of isotretinoin is on the HDL2-C subfraction. Apo A-1 and HDL-PL did not change significantly, suggesting that the reduction in HDL-C represents cholesterol depletion of the HDL particle rather than a reduction in HDL mass. After discontinuing isotretinoin, serum lipid parameters returned to baseline levels.