Concentration of moxifloxacin in plasma and tonsillar tissue after multiple administration in adult patients

Objectives: The antibacterial spectrum of moxifloxacin includes all the major respiratory pathogens, and its pharmacokinetics demonstrate high peak concentrations in plasma as well as at respiratory sites. Nevertheless, tonsillar tissue concentrations have never been investigated. In this study we determined the moxifloxacin concentrations in plasma and tonsillar tissue after the administration of three doses of moxifloxacin 400 mg to adult patients with chronic or recurrent tonsillitis undergoing tonsillectomy. Methods: This was an uncontrolled, open-label, randomized, parallel group study including 35 patients assigned randomly to five groups of 7 patients each, depending on the time between the last dose of moxifloxacin and plasma and tissue sampling. Moxifloxacin was given orally once daily for 3 days; its concentrations were measured using a validated HPLC assay and fluorescence detection. Each sample was analysed twice and the mean value obtained used for the statistical analysis. Pharmacokinetic data were analysed by presenting descriptive statistics of moxifloxacin concentrations in plasma and tonsillartissue. Results: C max occurred at 3 h in tonsillartissue (mean 8.96 mg/L) and in plasma (mean 3.20 mg/L), the tissue/ plasma concentration ratios (mean values) being constantly >2, ranging between 2.37 (after 2 h) and 2.93 (after 24 h), which indicates a prolonged maintenance of moxifloxacin concentration in tonsillar tissue compared with plasma. Variability among patients was present at 6 h, with the tonsillar tissue/plasma concentration ratio ranging between 0.8 and 3.4. Conclusions: Moxifloxacin achieves a good penetration in tonsillar tissue, which compares favourably with that reported for other fluoroquinolones. The moxifloxacin concentrations we observed exceed the MICs for the usual respiratory tract pathogens.