New pharmacologic aspects of CS-866, the newest angiotensin II receptor antagonist.

CS-866 is a new angiotensin II receptor blocker that has demonstrated effectiveness for lowering blood pressure in animal models of hypertension. Given the proposed involvement of the renin-angiotensin system in diabetic nephropathy and atherosclerosis, we have tested CS-866 in animal models of these conditions. The renal protective properties of CS-866 were examined in the Zucker diabetic fatty (ZDF) rat, a model of type 2 diabetes that develops progressive hyperglycemia, glomerulosclerosis, and proteinuria. Treatment of ZDF rats with CS-866 in the diet for 19 weeks resulted in a dose-dependent reduction in urinary protein excretion compared with vehicle-treated control rats, which was independent of changes in blood pressure and glycemic state. The antiatherosclerotic properties of CS-866 were tested in 2 animal models. In the first study, cynomolgus monkeys were fed a high-cholesterol diet for 6 months while receiving CS-866 or vehicle. At the end of this period, CS-866-treated animals had 64% less plaque area in the aorta than controls. CS-866 was also tested in the Watanabe heritable hyperlipidemic (WHHL) rabbit model of atherosclerosis. WHHL rabbits were treated for 32 weeks with CS-866 (1 mg/kg), pravastatin (50 mg/kg), a combination of the 2 drugs, or vehicle. CS-866 had no effect on plasma cholesterol levels and reduced blood pressures minimally. Pravastatin alone reduced serum cholesterol but had no effect on blood pressure or lesion area. In contrast, treatment with CS-866 resulted in a 40% reduction in lesion area compared with vehicle-treated control when given alone and a 50% reduction in combination with pravastatin. On the basis of results from animal models, CS-866 may be a useful treatment for diabetic nephropathy and atherosclerosis.