Although the study predates extensive use of echinocandins and voriconazole, these findings demonstrate that posaconazole is an alternative to salvage therapy for patients with invasive aspergillosis who are refractory to or intolerant of previous antifungal therapy.

A four-part, randomized, crossover study with healthy subjects evaluated the effects of gastric pH, the dosing frequency and prandial state, food consumption timing, and gastric motility on the absorption of posaconazole. In part 1, a single dose (SD) of posaconazole (400 mg) was administered alone or with an acidic beverage or a proton pump inhibitor (PPI), or both. In part 2, posaconazole (400 mg twice daily and 200 mg four times daily) was administered for 7 days with and without a nutritional supplement (Boost). In part 3, an SD of posaconazole (400 mg) was administered while the subjects were fasting and before, during, and after a high-fat meal. In part 4, an SD of posaconazole (400 mg) and the nutritional supplement were administered alone, with metoclopramide, and with loperamide. Compared to the results obtained with posaconazole alone, administration with an acidic beverage increased the posaconazole maximum concentration in plasma (C max ) and the area under the concentration-time curve (AUC) by 92% and 70%, respectively, whereas a higher gastric pH decreased the posaconazole C max and AUC by 46% and 32%, respectively. Compared to the results obtained with posaconazole alone, posaconazole at 400 mg or at 200 mg plus the nutritional supplement increased the posaconazole C max and AUC by 65% and 66%, respectively, and by up to 137% and 161%, respectively. Administration before a high-fat meal increased the C max and the AUC by 96% and 111%, respectively, while administration during and after the meal increased the C max and the AUC by up to 339% and 387%, respectively. Increased gastric motility decreased the C max and the AUC by 21% and 19%, respectively. Strategies to maximize posaconazole exposure in patients with absorption difficulties include administration with or after a high-fat meal, with any meal or nutritional supplement, with an acidic beverage, or in divided doses and the avoidance of proton pump inhibitors.

No abstract

Posaconazole 200 mg 3 times/day resulted in median plasma drug concentrations sufficiently high to prevent invasive fungal infections in HSCT recipients with GVHD, without compromising patient safety. Plasma posaconazole concentrations are generally unaffected by demographic variables, including race, sex, body weight, and age.

Previous in vivo studies have characterized the pharmacodynamic characteristics of two triazole compounds, fluconazole and ravuconazole. These investigations demonstrated that the 24-h area under the concentrationtime curve (AUC)/MIC ratio is the critical pharmacokinetic-pharmacodynamic (PK-PD) parameter associated with treatment efficacy. Further analysis demonstrated that a free-drug triazole 24-h AUC/MIC ratio of 20 to 25 was predictive of treatment success in both experimental models and clinical trials. We used a neutropenic murine model of disseminated Candida albicans infection to similarly characterize the time course activity of the new triazole, posaconazole. The PK-PD parameters (percent time above MIC, AUC/MIC ratio, and peak serum drug level/MIC ratio) were correlated with in vivo efficacy, as measured by organism number in kidney cultures after 48 h of therapy. Kinetics and protein binding following oral posaconazole dosing were performed in neutropenic infected mice. Peak levels and AUC from 0 h to ؕ values were nonlinear over the 16-fold dose range studied. Serum drug elimination half-life ranged from 12.0 to 17.7 h. Protein binding was 99%. Single dose postantifungal effect studies demonstrated prolonged suppression of organism regrowth after serum posaconazole levels had fallen below the MIC. 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 (AUC/MIC ratio R 2 ‫؍‬ 83%; peak serum drug/MIC ratio R 2 ‫؍‬ 85%; time that serum levels of posaconazole remained above the MIC R 2 ‫؍‬ 65%). Similar studies were conducted with 11 additional C. albicans isolates with various posaconazole susceptibilities (MIC, 0.015 to 0.12 g/ml) to determine if a similar 24-h AUC/MIC ratio was associated with efficacy. The posaconazole free-drug AUC/MIC ratios were similar for all of the organisms studied (6.12 to 26.7, mean ؎ SD ‫؍‬ 16.9 ؎ 7.8, P value, 0.42). These free-drug AUC/MIC ratios are similar to those observed for other triazoles in this model. Antimicrobial pharmacodynamic characterizations have provided an understanding of the relationship between drug exposure and treatment efficacy. Therapeutic outcome predictions based upon these pharmacodynamic studies have correlated well in treatment against both susceptible and resistant pathogens (3). In addition, the strength of these in vivo predictions has been shown to be independent of animal species, infection site, and duration of treatment studied. These pharmacodynamic analyses in animal infection models have proven useful for the design of optimal dosing regimens and the validation of susceptibility breakpoint guidelines (8, 9, 18).Prior in vivo studies have demonstrated that the pharmacokinetic-pharmacodynamic (PK-PD) parameter predictive of triazole efficacy against Candida albicans is the 24-h area under the concentration-time curve (AUC)/MIC rati...