Pharmacokinetics of oral posaconazole in allogeneic hematopoietic stem cell transplant recipients with graft-versus-host disease

Study Objective. To analyze the pharmacokinetics of posaconazole administered as prophylaxis for invasive fungal infections in recipients of hematopoietic stem cell transplants (HSCTs) who have graft-versus-host disease (GVHD). Design. Pharmacokinetic analysis in a subset of posaconazole-treated patients from a large, multicenter, phase III, randomized, double-blind, double-dummy, parallel-group trial that compared posaconazole with fluconazole. Setting. Ninety international medical centers. Patients. The subset of patients comprised 246 HSCT recipients for whom pharmacokinetic data were available. Intervention. All patients received posaconazole 200 mg oral suspension 3 times/day for a maximum of 16 weeks. Measurements and Main Results. Blood samples were collected after dosing on day 2; at weeks 2, 4, 8, and 12; and on the last day of oral treatment. After patients had received posaconazole for at least 7 days (i.e., after achieving steady state), both maximum observed posaconazole concentration (C-max) and average posaconazole concentration (C-av) were determined. Five patients developed invasive fungal infections while receiving treatment. Median C-av and C-max were 611 and 635 ng/ml, respectively, in these five patients and were 922 and 1360 ng/ml, respectively, in the 241 patients without invasive fungal infection. In patients without invasive fungal infection, posaconazole concentrations were not clinically affected by race, body weight, or age. Median plasma posaconazole concentrations were higher in patients with chronic GVHD than in those with acute GVHD. In 18 patients without invasive fungal infection who experienced diarrhea on the day of sampling, posaconazole concentrations were lower than the concentrations in patients without diarrhea. No relationship was observed between alanine amino transferase, aspartate aminotransferase, or bilirubin levels and posaconazole concentrations. Conclusion. 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.