Levofloxacin free plasma and muscle concentrations determined by microdialysis after intravenous dosing to Wistar rats

Levofloxacin is a broad spectrum synthetic antimicrobial used in the clinic for various disorders such as skin, urinary tract and respiratory infections1,5. The aim of this work was to study levofloxacin skeletal muscle distribution by analyzing free plasma and tissue concentrations after drug dosing to Wistar rats. Plasma and muscle levofloxacin concentrations were collected by microdialysis up to 18 h following 40 mg/kg i.v. bolus dosing and the drug was quantified by validated HPLC-fluorescence method3. The study was approved by CEUA/UFRGS (# 35131). Data was analyzed by non-compartmental approach using PKanalix® (Table 1). There was no statistical differences in the pharmacokinetic parameters obtained from plasma and muscle ( = 0.05). Tissue penetration factor < 1 could suggest active transport mechanism at skeletal muscle, similar to norfloxacin2 but in disagreement with previous report with smaller levofloxacin dose4.