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Enhanced penetration of moxifloxacin into rat prostate tissue evidenced by microdialysis
Felipe K Hurtado1, João Victor Laureano1, Graziela de A Lock1
1Pharmaceutical Sciences Graduate Program, College of Pharmacy, Federal University of Rio Grande do Sul, Av. Ipiranga 2752, 90610-000 Porto Alegre, RS, Brazil.
Abstract:
Moxifloxacin is reported to have increased distribution into the prostate compared with older fluoroquinolones such as norfloxacin and ciprofloxacin, being able to reach tissue-to-plasma concentration ratios greater than unity. However, most of these studies use tissue homogenates derived from biopsy samples, which can lead to overestimation of free concentrations as fluoroquinolones tend to accumulate in the intracellular space. The aim of this study was to investigate moxifloxacin pharmacokinetics in rat prostate interstitial fluid by microdialysis. Tissue pharmacokinetics was assessed by implanting a small microdialysis catheter in the prostate gland. Blood samples were simultaneously collected for assessing plasma pharmacokinetics. Analysis of plasma (N=154) and microdialysis (N=344) concentrations after a single intravenous dose of 6 or 12mg/kg moxifloxacin was conducted in the non-linear mixed-effect modelling software NONMEM v.6 as well by a non-compartmental approach. Moxifloxacin showed a significant tissue distribution in the prostate (AUCprostate,ISF/fu·AUCplasma=1.24±0.37), 59% higher than the value obtained for levofloxacin in a previous study. A three-compartment model with non-linear kinetics could adequately describe moxifloxacin pharmacokinetics in terms of curve fitting and precision in parameter estimation. The developed pharmacokinetic model indicates that passive diffusion and active transport are the mechanisms involved in moxifloxacin distribution to the prostate. These findings suggest that moxifloxacin could be a better alternative to levofloxacin for the treatment of chronic bacterial prostatitis owing to its enhanced tissue penetration and higher AUCtissue/MIC ratios, even though it is not yet approved by the US FDA for this indication.
Insights
Moxifloxacin demonstrates superior prostate penetration compared to older fluoroquinolones. This enhanced tissue distribution suggests it may be a more effective treatment for chronic bacterial prostatitis.
Area of Science:
- Pharmacology
- Pharmacokinetics
- Drug Distribution
Background:
- Moxifloxacin shows greater prostate distribution than older fluoroquinolones.
- Previous studies may overestimate free concentrations due to intracellular accumulation in biopsy homogenates.
Purpose of the Study:
- To investigate moxifloxacin pharmacokinetics in rat prostate interstitial fluid using microdialysis.
- To accurately assess prostate tissue drug concentrations and distribution.
Main Methods:
- Microdialysis catheter implanted in rat prostates for interstitial fluid collection.
- Simultaneous blood sampling for plasma pharmacokinetic analysis.
- Non-linear mixed-effects modeling (NONMEM) and non-compartmental analysis of concentration-time data.
Main Results:
- Moxifloxacin achieved a prostate interstitial fluid to unbound plasma AUC ratio of 1.24±0.37, 59% higher than levofloxacin.
- A three-compartment model with non-linear kinetics accurately described moxifloxacin pharmacokinetics.
- Passive diffusion and active transport mechanisms are implicated in prostate distribution.
Conclusions:
- Moxifloxacin exhibits enhanced penetration into rat prostate interstitial fluid.
- Its pharmacokinetic profile suggests potential as a superior alternative to levofloxacin for chronic bacterial prostatitis.
- Higher tissue-to-plasma concentration ratios support improved efficacy for prostate infections.
