A rapid high-performance liquid chromatography assay of glibenclamide in serum

A rapid high-performance liquid chromatography (HPLC) determination of glibenclamide in human serum is described. Serum samples to which flufenamic acid has been added as internal standard were treated with acetonitrile as a protein precipitant. After centrifugation, separation and reconstitution, the redissolved residue was eluted from 5 mu Spherisorb C-8 reversed phase column at ambient temperature using a mobile phase consisting of acetonitrile-water (45:55 v/v) at pH 3.7-3.8 and pumped at a flow rate 2 ml/min. The effluent was monitored at 230 nm. The analysis time was no longer than 12 min. A linear relationship between the peak height ratio (glibenclamide/flufenamic acid) and concentration was obtained in the range 20-400 ng/ml. A typical calibration curve has a regression equation y = 0.0035x + 0.015 (r = 0.9999). The detection limit of glibenclamide in serum was 20 ng/ml. The mean recovery of drug from serum samples spiked with known amounts of glibenclamide was 96.77%. Within-day and between-day coefficients of variation were 1.6-4.0% and 1.4-3.5%, respectively. Stability testing indicated that glibenclamide was stable for at least 10 days in serum -20 degrees C. The method developed was applied to determine some pharmacokinetic parameters after the oral administration of 5 mg glibenclamide tablets to a human volunteer.