Improved HPLC method for the determination of moxifloxacin in application to a pharmacokinetics study in patients with infectious diseases.

Objective. To develop a simple and rapid high-performance liquid chromatography (HPLC) method for measuring moxifloxacin concentration in human plasma. Methods. Following a single step liquid-liquid extraction, analytes along with an internal standard (IS) were separated using an isocratic mobile phase of 0.1% triethylamine (adjusted pH to 4.8 with phosphoric acid)/acetonitrile (80/20, v/v) at flow rate of 1 mL/min on reverse phase Kromasil C18 column (250 mm × 4.6 mm, 5  μ m) at room temperature. Results. Total analytical run time for selecting moxifloxacin was 15 min. The assays exhibited good linearity (r (2) = 0.9998) over the studied range of 25 to 5000 ng/mL. The absolute recovery rate of low, medium, and high concentrations were 69.88%, 78.86%, and 78.51%, respectively. The relative recovery rates were 98.50%, 96.61%, and 101.79%, respectively. Coefficient of variation and error at both of the intraday and interday assessments were less than 4.7%. Conclusions. The results indicated that this method is a simple, rapid, precise and accurate assay for the determination of moxifloxacin concentrations in human plasma. This validated method is sensitive and reproducible enough to be used in pharmacokinetic studies.