Lipoprotein particle analysis comparing simvastatin and fenofibrate.

This study compares the effects of fenofibrate and simvastatin in primary hypercholesterolemia, with particular regard to lipoprotein particles, as defined by their apolipoprotein composition: LpAI, LpAII: AI, LpE:B, LpCIII:B. This was a double-blind study in which patients were randomized to 2 groups, one receiving simvastatin 20 mg once daily and the other receiving fenofibrate 200 mg b.i.d., if their total cholesterol and their LDL cholesterol remained above 7.60 mmol/l (300 mg/dl) and 4.95 mmol/l (195 mg/dl) after a 4-week placebo period. Simvastatin dosage was doubled at the end of 6 weeks of therapy if the LDL-cholesterol level remained above 3.55 mmol/l (140 mg/dl). Analyses were done after 6 and 10 weeks of therapy. Apolipoprotein AI was increased significantly only at week 10 with fenofibrate (+7.4%). Simvastatin had a more pronounced effect than fenofibrate on apolipoprotein B. There was a significant difference between drugs at weeks 6 and 10. No change was observed in the LpAII:AI level with simvastatin, whereas fenofibrate increased these particles quite significantly (+13.9 and +22.3%). The drugs had opposite effects on LpAI (+2.5 and +5.6% with simvastatin; -12.8 and -15.1% with fenofibrate). LP E:B (-33.0 and -40.8% with simvastatin; -53.8 and -52.2% with fenofibrate) and LpCIII:B (-23.8 and -31.8% with simvastatin; -35.1 and -43.5% with fenofibrate) were decreased by both drugs, but fenofibrate was significantly more effective in reducing these particles than simvastatin at week 6. This study suggests that both drugs led to different structural modifications of the lipoproteins, which would not be revealed by total apolipoprotein analysis. These differences are probably related to the mechanisms of action of these drugs.