Pharmacokinetics of oral posaconazole in neutropenic patients receiving chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome

Study Objective. To analyze the pharmacokinetics of posaconazole administered as prophylaxis for invasive fungal infection (IFI) in neutropenic patients receiving chemotherapy for acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS). Design. Pharmacokinetic subanalysis of a phase III, prospective, randomized, multicenter, evaluator-blinded trial comparing posaconazole with standard azoles (fluconazole and itraconazole). Patients. One hundred ninety-four patients with AML or MDS who received posaconazole oral suspension 200 mg 3 limes/day with meals or a nutritional supplement for a minimum of 7 days to achieve steady state and for a maximum of 12 weeks. Intervention. For the first 20 patients, blood samples were collected before the first dose on day 8 and at 2, 4, 6, and 24 hours after that first dose; for all other patients, blood samples were collected at 1. and 3 hours after the first dose on day 8 and during the first episode of evaluation for a possible IFI. Measurements and Main Results. The effects of the following covariates on average (C-av) and maximum (C-max) posaconazole plasma concentrations at steady state were explored: age, sex, and race-ethnicity; proven or probable IFI; baseline body weight and body surface area; and baseline (on or before day 7) increases in liver enzyme levels, mucositis, neutropenia, diarrhea, vomiting, or use of an H-2-receptor antagonist or proton pump inhibitor. Diarrhea, proton pump inhibitor use, gamma-glutamyl transferase level of 2 or more times the upper limit of normal, and race-ethnicity reduced C-av. Although statistically significant, these results were not considered clinically significant and did not necessitate posaconazole dosage adjustments. Mean C-av and C-max values did not appear different in the six patients with IFIs (three with proven IFIs, three with probable IFIs) compared with the entire sample of 194 patients; however, a definitive conclusion cannot be made due to the small sample size of patients with IFI. No factor found to affect posaconazole concentrations predominated in patients with IFIs. Conclusion. Oral posaconazole 200 mg 3 times/day provided plasma concentrations adequate for preventing IFIs. No dosage adjustments are recommended based on any covariate tested.