Background: New formulations of posaconazole, the delayed-release (DR) tablet and intravenous (IV) solution, provide pharmacokinetic improvements that enhance administration, including higher serum concentrations when compared to the oral suspension. These new formulations were approved by the FDA in 2013 and 2014, respectively and there is a lack of literature on their appropriate dosing and monitoring in the treatment of invasive fungal infections. The objective of this study was to evaluate use and adherence to hospital guidelines for the IV solution and DR tablet formulations of posaconazole at NewYork-Presbyterian Columbia University Medical Center (NYP/CUMC).
Methods: This was an IRB-approved, single center, retrospective chart review of 123 adult patients admitted to NYP/CUMC between January 1, 2014 through September 25, 2015 who received at least one dose of IV or DR posaconazole. Patient demographics as well as posaconazole dosing, therapeutic drug monitoring, liver function tests, and concomitant medications were collected.
Results: There were 29 and 94 patients identified who received IV and DR posaconazole, respectively. Loading doses of posaconazole were utilized in 53% of the patients, followed by a maintenance dose of 300mg daily in 81% of patients. Only 40% of patients had a posaconazole level drawn during therapy. Posaconazole levels were drawn after a median of 7.2 (IQR, 4-8) days of therapy. A comparison of posaconazole levels can be seen in figure 1. Of the patients that had posaconazole levels drawn, 37% were ≥0.5-0.9 mcg/mL and 27% ≥1 mcg/mL. Three patients were identified with levels ≥3 mcg/mL. All three of these patients were receiving 300mg daily.
Conclusion: A significant portion of patients with posaconazole therapeutic drug monitoring had levels that were not sufficient for the treatment of invasive fungal infections. Based on this finding, posaconazole at currently recommended doses may not be an optimal agent to use for the treatment of fungal infections in the acute setting.
B. Nelson, None