Clofibrate pharmacokinetics: effect of elevation of plasma-free fatty acids

The pharmacokinetics of rho-chlorophenoxyisobutyrate (CPIB), the active metabolite of clofibrate were determined following intravenous administration in the rat. Serum CPIB concentrations were measured using an new TLC-GLC method. The results agree favourably with pharmacokinetics in human subjects after oral administration of clofibrate. Both clofibrate and free fatty acids (FFA) are extensively bound to circulating plasma proteins. When plasma FFA were elevated to about 2,000 muEq/1, the CPIB elimination half-life decreased form 19.3 h in controls to 7.3 h. Thus, elevation of FFA appears to significantly alter the pharmacokinetics of a highly bound drug.