A simple and sensitive assay for quantification of levofloxacin in dried rat plasma by HPLC and its application in a pharmacokinetic study

Levofloxacin is an antibacterial drug with favorable pharmacodynamic and pharmacokinetic properties for the treatment of a variety of infections including multi-drug resistance tuberculosis. In this study, a simple and sensitive bioanalytical method for determination of levofloxacin in micro-samples (10 μL) of rat plasma was developed, validated and applied succesfully in a pilot pharmacokinetic study. Levofloxacin and internal standard were extracted by a dry plasma spot technique at controlled temperature. Separation of compounds was achieved with a Symmetry C18 column and a mobile phase of potassium monobasic phosphate 0.01M (pH 3.3) and acetonitrile (86:14 v/v). Detection of compounds was made by a UV detector. The method was linear from 0.05 to 5 μg/mL and demonstrates selectivity, accuracy and precision in the quantification of levofloxacin. Aditionally, pharmacokinetic results were similar to previous reports. We conclude the method is suitable for determination of levofloxacin using only 10 μL of rat plasma and conventional chromatography instrumentation.