Purpose: To develop a simple, rapid and sensitive high performance liquid chromatography (HPLC) method for the determination of cefadroxil monohydrate in human plasma.

Methods: Schimadzu HPLC with LC solution software was used with Waters Spherisorb, C18 (5 µm, 150mm × 4.5mm) column. The mobile phase was sodium dihydrogen phosphate buffer pH 4.0 and methanol in a ratio of 96:4. Flow rate was 1.5 ml/min and injection volume was 100 µl. Peak response was detected at 260 nm.

Results: System suitability results revealed that the coefficient of variation (CV) for retention time, peak response, tailing factor and resolution of six replicate injections was < 3 %. The method was selective to determine cefadroxil in plasma because there was no peak interference of plasma with cefadroxil at its retention time (7.792 min). Linearity was in the range of 0.5 - 30 µg/ml with slope and intercept of 41694.53 and 22614.87, respectively (R² = 0.9953). Limit of detection (LOD) and lower limit of quantification (LLOQ) of the method were 0.03 and 0.06 µg/ml, respectively. Absolute recovery of cefadroxil from plasma was in the range 71 - 90.4 %, while inter-day and intra-day analysis showed satisfactory precision and accuracy; thus, the method was reproducible with the range of CV, i.e., 0.35 - 4.01 and 1.88 - 7.9 % for interday and intraday precision, respectively.

Conclusion: The developed method being simple, rapid, reproducible can be suitably employed in pharmacokinetic and bioequivalence studies of cefadroxil monohydrate.