Pharmacokinetics in Non-Insulin-Dependent Diabetics of the Aldose Reductase Inhibitor, Zopolrestat

The pharmacokinetics of zopolrestat have been examined in non-insulin-dependent diabetic patients after oral administration of a single dose of 1000 mg zopolrestat. T(max) ranged from 2 to 4 h with a mean C(max) of 100 &mgr;g ml(minus sign1). Mean plasma half-life of zopolrestat was 26.9 h. The same patients were also administered oral doses of 1000 mg day(minus sign1) for 10 consecutive days. Mean T(max) was 4.3 h and mean C(max) was 208 &mgr;g ml(minus sign1). Plasma accumulation, the ratio of AUC((0--24)) for the last dose to AUC((0--24)) for the first dose, was 2.67. Apparent oral clearance was 5.71 ml min(minus sign1) and apparent volume of distribution was 12.9 L. The mean urinary excretion of unchanged drug over the 24-h period following the last dose was 36% of the dose while another 7% of the dose appeared in the urine as an acylglucuronide of zopolrestat. Renal clearance of zopolrestat was 1.82 ml min(minus sign1). Binding of zopolrestat to plasma proteins exceeded 99% and was concentration dependent.