Decreased isavuconazole trough concentrations in the treatment of invasive aspergillosis in an adult patient receiving extracorporeal membrane oxygenation support

PURPOSE: We present the case of a 56-year-old man with stage IV sarcoidosis on veno-venous extracorporeal membrane oxygenation (VV-ECMO) support for the management of respiratory failure receiving treatment with isavuconazole for invasive aspergillosis. SUMMARY: VV-ECMO is an increasingly utilized life support therapy for patients with cardiac and/or respiratory failure, but its impact on medication dosing is poorly understood. In our patient with invasive Aspergillus infection receiving VV-ECMO, because of difficulty achieving therapeutic serum concentrations of voriconazole, we administered isavuconazole 372 mg intravenously (IV) every 8 hours for 6 doses followed by 372 mg IV once daily. Isavuconazole has a favorable pharmacokinetic and safety profile compared to other azole antifungal agents, but its high protein binding and lipophilicity raise concerns about drug sequestration in the VV-ECMO circuit. To optimize the efficacy and safety of this treatment, the isavuconazole trough concentration was measured at days 5 and 17, at which time it was 1.7 and 0.7 μg/mL, respectively. The dose was subsequently increased to 744 mg IV once daily, and serum trough concentrations were measured 5 and 8 days after dose adjustment, corresponding to 3.7 and 2.9 μg/mL, respectively. To our knowledge, this is the third report to describe inadequate isavuconazole trough concentrations during VV-ECMO support when utilizing standard doses. CONCLUSION: In the case described here, standard-dose isavuconazole (372 mg every 8 hours for 6 doses followed by 372 mg daily) did not achieve target trough concentrations in a patient receiving concomitant ECMO support.