Monitoring posaconazole blood concentrations

Posaconazole plasma concentration monitoring is recommended in all patients regardless of the formulation used or indicationDolton 2012Lai 2020Miceli 2015Pham 2016Yeoh 2021.

The slow-release tablet formulation of posaconazole has higher bioavailability than the oral suspension. Approximately 85% of patients taking the slow-release tablet or parenteral formulation for prophylaxis have adequate posaconazole plasma concentrations; only 60% of patients taking the oral suspension have adequate plasma concentrationsDurani 2015Jung 2014Pham 2016.

Posaconazole has a long half-life, so the concentration is best measured at least 5 to 7 days after starting therapy. A trough concentration of at least 1 mg/L is appropriate for treatment regimens, and a trough concentration of at least 0.5 mg/L is reasonable for prophylaxisChau 2021Dolton 2012John 2019Lai 2020Walsh 2007. Some institutions recommend that the posaconazole plasma concentration should not exceed 4 mg/L because data show that posaconazole-induced pseudohyperaldosteronism can occur at concentrations of 4 mg/L or moreChau 2021.

For information on posaconazole plasma concentration monitoring and dose adjustment in haematology patients, see the Australian and New Zealand antifungal consensus guidelines.