Study on Determination of Azithromycin in Human Plasma by HPLC-MS/MS and Its Bioequivalent

OBJECTIVE To develop an HPLC-MS/MS assay for determination of azithromycin in human plasma and to investigate the pharmacokinetics and bioequivalence of azithromycin granules in healthy volunteers. METHODS Ninteen volunteers were randomly divided into two groups (test and reference), with double cross over design, a single oral dose of 500 mg of test and reference azithromycin granules was administered to each volunteer. The concentration of azithromycin in plasma was determined by HPLC-MS/MS and pharmacokinetic parameters were calculated by DAS 2.0 practical pharmacokinetics program. RESULTS The main pharmacokinetic parameterswere of test and reference azithromycin granules were as follows: t1/2 were (44.7 ±15.2) h and(42.0 ±13.0) h; T_max were (2.5 ±1.1) h and (2.6 ±1.7) h; C_max were (574.6±209.2) ng·mL^-1 and (594.5 ±229.9)ng·mL^-1 ; AUC_0-144 were(5 319.6±2 507.8) h·ng·mL^-1 and (5 710.7±2 710.1) h·ng·mL^-1; AUC_0-∞ were(5 704.2±2 858.7) h·ng·mL^-1 and(6 010.0±2 808.1) h·ng·mL^-1. The relative bioavailability of tested to reference granules was (94.2±15.7)% according to AUC_0-144. CONCLUSION The two formulations were bioequivalent.