title: In vivo pharmacokinetics and pharmacodynamics of a new triazole, voriconazole, in a murine candidiasis model.
abstract: In vivo studies have described the pharmacodynamic (PD) characteristics of several triazoles. These investigations have demonstrated that the 24-h area under the concentration-time curve (AUC)/MIC ratio is the critical pharmacokinetic (PK)-PD parameter associated with treatment efficacy. Further analyses from these in vivo studies have demonstrated that a triazole free drug 24-h AUC/MIC of 20 to 25 is predictive of treatment success. We used a neutropenic murine model of disseminated Candida albicans infection to similarly characterize the PK-PD of the new triazole voriconazole. PK and PD parameters (percentage of time that the concentration remains above the MIC [T > MIC], AUC/MIC ratio, and peak level in serum/MIC ratio) were correlated with in vivo efficacy, as measured by the organism number in kidney cultures after 24 h of therapy. Voriconazole kinetics and protein binding were studied in infected neutropenic mice. Peak level/dose and AUC/dose values ranged from 0.1 to 0.2 and 0.1 to 0.7, respectively. The serum elimination half-life ranged from 0.7 to 2.9 h. The level of protein binding in mouse serum was 78%. Treatment efficacy with the four dosing intervals studied was similar, supporting the AUC/MIC ratio as the PK-PD parameter predictive of efficacy. Nonlinear regression analysis also suggested that the AUC/MIC ratio was strongly predictive of treatment outcomes (R(2) for AUC/MIC ratio = 82%, R(2) for peak level/MIC ratio = 63%, R(2) for T > MIC = 75%). Similar studies were conducted with nine additional C. albicans isolates with various voriconazole susceptibilities (MICs, 0.007 to 0.25 micro g/ml) to determine if a similar 24-h AUC/MIC ratio was associated with efficacy. The voriconazole free drug AUC/MIC ratios were similar for all of the organisms studied (range, 11 to 58; mean +/- standard deviation, 24 +/- 17 [P = 0.45]). These AUC/MIC ratios observed for free drug are similar to those observed for other triazoles in this model.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000935:Antifungal Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D019540:Area Under Curve; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D002177:Candidiasis / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism*; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D025141:Drug Resistance, Fungal; D005260:Female; D015725:Fluconazole / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism; D051379:Mice; D008826:Microbial Sensitivity Tests; D009503:Neutropenia / Q000378:metabolism; D011743:Pyrimidines / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology*; D014230:Triazoles / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology*; D065819:Voriconazole
chemical_list: D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D015725:Fluconazole; D065819:Voriconazole