Serum posaconazole levels among haematological cancer patients taking extended release tablets is affected by body weight and diarrhoea: single centre retrospective analysis

The posaconazole extended release tablet formulation was developed to improve bioavailability relative to the oral suspension. Therapeutic drug monitoring has been used to optimise posaconazole dosing to achieve a target trough level 0.7gml(-1). We retrospectively evaluated 28 patients with haematological malignancies who received posaconazole tablets for antifungal prophylaxis. Posaconazole serum trough levels were obtained 5days after initiation of therapy. Mean trough level was 1.19 +/- 0.63gml(-1), and 71% achieved a trough level 0.7gml(-1). Diarrhoea was associated with lower mean trough levels (0.65 +/- 0.08gml(-1) vs. 1.31 +/- 0.13gml(-1)), P=0.002. Mean trough levels were lower in patients 90kg (0.74 +/- 0.09gml(-1)) vs. <90kg (1.32 +/- 0.14gml(-1)), P=0.002 and in patients with body mass index (BMI) 30 (0.89 +/- 0.13gml(-1)) vs. BMI<30 (1.29 +/- 0.14gml(-1)), P=0.05. Posaconazole delayed release tablets attain appropriate trough levels in most patients, but patients with a higher weight and those experiencing diarrhoea are more likely to have lower levels.