Assessment of relative bioavailability and bioequivalence of azithromycin granules and tablets

Objective To study the pharmacokinetics and relative bioavailability of azithromycin granules and tablets.Methods A liquid chromatography-tandem mass spectrometry(LC-MS-MS) method was developed to determine plasma concentrations of azithromycin in 24 healthy Chinese male volunteers following a 0.5 g dose of azithromycin granules(test formulationⅠ),azithromycin tablets A(test formulationⅡ)and azithromycin tablets B(reference formulation)with three cross-over design,the blood concentration-time curves were ploted and the main pharmacokinetic parameters were calculated.Results The main pharmacokinetic parameters of testⅠ,testⅡand reference formulation were:tmax(1.9±0.6),(1.9 ±0.7),(1.8±0.6)h;ρmax(441.0±129.5),(421.7±142.8),(426.2±128.1)μg·L-1;t1/2(48.0±10.7),(44.8±8.0),(45.6±9.8)h;AUC0-t(4 564.6±1 312.0),(4 743.1±1 616.1),(4 654.6±1 489.4)μg·h·L-1;AUC0-∞(5 224.6±1 529.7),(5 373.4±1 854.7),(5 278.7±1 675.9)μg·h·L-1,respectively.According to AUC0-t,the relative bioavailability of azithromycin granules and tablets were(99.7±14.0)% and(101.8±13.8)%.Conclusions According to the two one-side tests,azithromycin of tests and reference formulations are bioequivalent.