Posaconazole concentrations after allogeneic hematopoietic stem cell transplantation

IntroductionPosaconazole is recommended for prophylaxis of fungal infections and for salvage therapy of invasive aspergillosis after stem cell transplantation. An impact of drug concentration on efficacy has been suggested. MethodsIn this study, we investigated serum levels of posaconazole in 262 samples from 64 allogeneic stem cell recipients. ResultsA high degree of interindividual variation was observed. Concentrations were significantly higher for male patients compared with female patients (median 570 and 426ng/mL, respectively), but no differences for age or dosing groups (400mg twice daily [BID] or 200mg three times a day) could be detected. The predictive value of the first determined posaconazole concentration in steady state and of a concentration >500 and 700ng/mL at any time was evaluated, compared with patients with a first level <300ng/mL (mean 10.3%, median 0%). ConclusionIn patients receiving 400mg BID, the mean rate of serum levels >500ng/mL in subsequent determinations was higher, if the first serum concentration during steady state was >300ng/mL (mean 61.1%, median 60%, P=0.002) or >500ng/mL (67.7%, median 75%, P=0.002). Based on this retrospective analysis, a posaconazole serum concentration >500ng/mL at any time point might also help to predict sufficient drug concentrations.