In 17 patients with primary mixed
hyperlipidemia we studied levels and composition of
lipoproteins in fasting plasma,
lipoprotein-modifying
enzymes, and postprandial
lipoprotein metabolism after an oral fat-tolerance test supplemented with
vitamin A before, and 12 weeks
after treatment with
etophylline clofibrate. With treatment, fasting plasma
cholesterol,
triglycerides, and the levels of
very low density lipoproteins (VLDL),
intermediate density lipoproteins (IDL), and
low density lipoproteins (
LDL) decreased significantly;
high density lipoprotein (
HDL) cholesterol increased significantly. Treatment caused also an increase in the
protein content of IDL, a decrease in the
triglyceride content of
LDL, and an increase in the size of
LDL as assessed by gradient gel electrophoresis. Concentrations of
triglycerides,
chylomicrons, and
chylomicron remnants after an oral fat load supplemented with
vitamin A decreased by 33%, 30% and 6%, respectively (P < 0.005; P < 0.01; and P < 0.05). The activity of
lipoprotein lipase and hepatic
lipase in postheparin plasma increased by 51% and 45%, respectively (P < 0.01; P < 0.05). We found a decrease in the mass concentration of
cholesteryl ester transfer protein (P < 0.05). Stepwise multiple regression analysis showed that the
triglyceride content of
LDL is determined primarily by fasting
triglycerides (r = + 0.53, P < 0.05;baseline) and
cholesteryl ester transfer protein (r = + 0.49, P < 0.05; 12 weeks); in contrast, the
triglyceride content of HDL3 is determined exclusively by accumulation of postprandial
triglycerides (r = + 0.67; P < 0.05; baseline) and postprandial
chylomicrons (r = +0.87; P < 0.005; 12 weeks). We conclude that hypolipidemic treatment with
etophylline clofibrate favorably affects the cardiovascular risk factor profile in primary mixed
hyperlipidemia.