THE SHORT‐ AND LONG‐TERM EFFECTS OF BEZAFIBRATE IN THE RAT*

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Abstract
Bezafibrate is a potent hypolipidemic agent, which causes marked proliferation of peroxisomes in rat liver. At the same dosage, bezafibrate is more effective in male than in female rats. This is probably related to divergent pharmacokinetics, which cause differences in drug level in serum and liver. The volume density of peroxisomes and several of their enzymes such as carnitine acetyl transferase and acyl-COA oxidase increase in a dose-related fashion. The hypolipidemic effect of bezafibrate, however, does not correlate with the used dosage. This implies that peroxisomal proliferation may play only a minor role in the hypolipidemic action of bezafibrate. In animals treated for 26 months with 300, 750, or 1500 ppm bezafibrate, the relative liver weight and serum triglycerides did not differ significantly from controls. Peroxisomal proliferation varied in different cells, being most prominent in single hepatocytes. The liver catalase activity was significantly reduced, but carnitine acetyl transferase was increased. Abnormal peroxisomes and mitochondria with longitudinal cristae were quite frequent. In one focus, catalase activity was severely diminished ahd peroxisomes were markedly reduced. The incidence of liver tumors was the same (1-3%) in treated animals as in controls.