DETERMINATION OF ANTIPYRINE AND METABOLITES IN PLASMA OF A PATIENT WITH MILD RENAL-FAILURE

A method has been developed for the simultaneous determination of anti pyrine and its three major metabolites in plasma of patients with rena l failure. Plasma samples (500 mu l) were hydrolyzed with beta-glucuro nidase/aryl sulphatase. The compounds, after addition of sodium chlori de, were extracted with chloroform:ethanol (90:10, v/v) in acidic medi um. Chromatographic conditions comprise a C-18,, column, a mobile phas e with 30% methanol and 70% 0.25N sodium acetate buffer (pH 5.0), a to tal run time of 10 minutes, and ultraviolet absorbance detection at 25 4 nm. Confidence limits showed 0.5 to 40.0 mu g/ml(-1) linearity (r(2) = 0.999); 0.1 mu g/ml(-1) HMA, 0.05 mu g/ml(-1) antipyrine and NORA, and 0.5 mu g/ml(-1) OHA sensitivity and absolute recovery >95%. Interp recision and intraprecision expressed as coefficient of variation were <10% for all compounds investigated. The assay shows to be suitable f or pharmacokinetics and drug metabolism studies after administration o f a single oral dose of 500 mg of antipyrine to a patient with hyperte nsion and chronic renal failure (CLCR = 34.17 ml/min(-1); 1.73m(-2)).