OBJECTIVE To determine
azithromycin in human
plasma by a
HPLC-MS method, and to study its
relative bioavailabili-ty.METHODS Azithromycin concentrations in plasma were determined by HPLC-MS.The test and reference formulations of azithromycin were given to 18 healthy male volunteers. Bioequivalence was determined by a two one-side t-tests.RESULTS The calibration curve was linear within the range of 2.5-800 μg·L-1(r= 0.999 3) ,the recovery was 98.1% , the RSDs of intra- and inter-day were no more than 11.3% and 8.6% .After a single oral dose of 500 mg azithromycin test or reference dispersible tablet,the main
pharmacokinetic parameters were as follows: AUC0-120(5 856.5±1 423.6) and (6096.8±1 111.0)μg·h·L-1,ρmax(520.1±94.1) and (558.8±74.0)μg·L-1,tmax(1.4±0.4) and (1.3±0.2) h ,t1/2(36.1±10.2) and (36.2±11.7) h, respectively. Relative
bioavailability was (96.3±16.0)%. CONCLUSION The method is accurate and sensitive with no endogenous interference. No significant difference exists among the main pharmacokinetic parameters for the test
tablets and the reference tablets. The two formulations are bioequivalent.
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