Pharmacokinetics and Bioequivalence of 2 Dosage Forms of Azithromycin Tablets in Healthy Volunteers

Objective To develop a microbiological method for the determination of the blood concentration of azithromycin so as to assess the bioequivalence of the enteric-coated azithromycin tablets and reference azithromycin tablets in healthy volunteers. Methods The azithromycin concentrations in the blood plasma were determined with by a microbiological method at different time points after a single oral dose of 500 mg of tested azithromycin enteric-coated tablets and ordinary azithromycin tablets given respectively to each of the 24 healthy male volunteers in an open randomized crossover design.The pharmacokinetic parameters and relative bioavailability were calculated for the assessment of the bioequivalence of the 2 dosage forms. Results The AUC_(0→144 h)of the tested azithromycin enteric-coated tablets and ordinary azithromycin tablets were(21.021±4.053) and(20.597±3.850) mg·h~(-1)·L~(-1),C_(max) were(0.583±0.073)and(0.603±0.061) mg·L~(-1),t_(max)were(3.900±0.800)and(3.000±0.700)h,t_(1/2) were(29.799±1.935)and(28.850±1.598)h,respectively.These main pharmacokinetic parameters showed that the differences between the 2 dosage forms of the drug were not statistically significant. Conclusion The method was simple,convenient and rapid. The 2 dosage forms of azithromycin were bioequivalent.The absorption of the tested azithromycin enteric-coated tablets in the human body,however,was slower than that of the reference tablets.