Comparative bioavailability of two cefadroxil products using serum and urine data in healthy human volunteers

1. The aim of the present study was to assess the bioequivalence of two cefadroxil products, namely Ultracef (a reference product) in the form of a 500 mg capsule (produced by Bristol-Myers Squibb Laboratories, Princeton, NJ, USA) and Roxil (a test product) in the form of a 500 mg capsule (produced by Tabuk Pharmaceutical Manufacturing, Tabuk, Saudi Arabia). 2. The study was performed under US Food and Drug Administration (FDA) guidelines (http://www.fda.gov/cder) on 24 healthy male subjects. Both products were administered orally as a single dose (1 x 500 mg capsule) separated by a 1 week washout period. Following oral administration, blood and urine samples were obtained and analysed for cefadroxil concentrations using a sensitive and specific HPLC assay. 3. There were no statistically significant differences between the two products in either the mean concentration-time profiles or the cumulative urinary excretion of cefadroxil at various times. Similarly, no statistical significance was observed in the pharmacokinetic parameters reflecting rate and extent of drug absorption. The relative extent of drug absorption, assessed by calculating the area under the curve (AUC) ratio for Roxil/Ultracef for 10 h and for infinity was 0.94 with 90% confidence limits (CL) of 0.91-0.98. In agreement with serum data, the average ratio (Roxil/Ultracef) of the cumulative amount of cefadroxil excreted in urine 10 h after the dose was found to be 0.97, with 90% CL of 0.88-1.05. The CL of the AUC and cumulative urinary excretion ratios are within the FDA accepted limits for bioequivalent products (0.80-1.25). 4. These findings show that serum and urine data of cefadroxil are in agreement and indicate that Roxil (the test product) and Ultracef (the reference product) are bioequivalent in terms of the rate and extent of drug absorption.