Fluctuations in vancomycin CNS tissue concentrations following intermittent and continuous infusions in the rat

Use of microdialysis for the assessment of fluoroquinolone pharmacokinetics in the clinical practice

Antibacterial drugs, including fluoroquinolones, can exert their therapeutic action only with adequate penetration at the infection site. Multiple factors, such as rate of protein binding, drug liposolubility and organ blood-flow all influence ability of antibiotics to penetrate target tissues. Microdialysis is an in vivo sampling technique that has been successfully applied to measure the distribution of fluoroquinolones in the interstitial fluid of different tissues both in animal studies and clinical setting. Tissue concentrations need to be interpreted within the context of the pathogenesis and causative agents implicated in infections. Integration of microdialysis -derived tissue pharmacokinetics with pharmacodynamic data offers crucial information for correlating exposure with antibacterial effect. This review explores these concepts and provides an overview of tissue concentrations of fluoroquinolones derived from microdialysis studies and explores the therapeutic implications of fluoroquinolone distribution at various target tissues.

Successful management of discovered pH dependence in vancomycin recovery studies: novel HPLC method for microdialysis and plasma samples

Vancomycin is a glycopeptide antibiotic approved for the treatment of serious infections or patients allergic to beta-lactams. A rapid HPLC assay using UV detection for the determination in microdialysate and human plasma was developed. After sample preparation, using methanol and trichloroacetic acid for plasma and water for microdialysate, 20 microL were injected and separated on a RP(18) column. Overall, the assay exhibited good precision and accuracy. The diffusion properties of vancomycin investigated in in vitro microdialysis experiments revealed an unfavourable concentration dependence avertable by keeping a constant pH using phosphate buffer as perfusate. The mean relative recoveries were 27.8% [coefficient of variation (CV) 11.1%] and 33.2% (CV 8.3%) for retrodialysis and recovery experiments, respectively. Following characterization of vancomycin in in vitro microdialysis, the developed setting is suitable for application in (pre-)clinical studies.