Gemfibrozil increases both apo A-I and apo E concentrations. Comparison to other lipid regulators in cholesterol-fed rats.

HDL cholesterol (HDL-C) was increased by gemfibrozil (+3.6-fold), fenofibrate (+1.3-fold) and ciprofibrate (+1.2-fold) but not clofibrate or bezafibrate when dosed PO at 50 mg/kg for 2 weeks in cholesterol-fed rats. Cholesterol in apo B-containing lipoproteins decreased with gemfibrozil (-76%), clofibrate (-12%) and ciprofibrate (-12%). Plasma apo B decreased to the greatest extent with gemfibrozil (-86%) followed by ciprofibrate (-47%), fenofibrate (-40%), clofibrate (-24%) and bezafibrate (-20%). Only gemfibrozil increased plasma apo E levels which are characteristically low in this rat model. Gemfibrozil, fenofibrate and ciprofibrate increased apo A-I concentrations. It is concluded that plasma lipid regulators which elevate HDL in this model might do so by altering the metabolism and hence plasma concentration of apoAI (fenofibrate, ciprofibrate) or both apo E and A-I (gemfibrozil). It is hypothesized that drugs which alter the metabolism of both HDL peptides result in the greatest HDL-C elevation in the rat.