Therapeutic drug concentrations of isavuconazole following the administration of isavuconazonium sulfate capsules via gastro-jejunum tube: A case report.

Invasive fungal infections are a common complication in immunocompromised patients, such as organ transplant recipients. Isavuconazole is a broad-spectrum azole antifungal for the treatment of aspergillosis and mucormycosis. The package insert for isavuconazole recommends against opening the capsule for administration through enteral feeding tubes. We describe the case of a 68-year-old man with a complex post-lung transplant course receiving isavuconazole for presumed invasive aspergillosis (bronchial alveolar lavage galactomannan index of >3.75) therapy administered through a gastrostomy-jejunostomy tube (G-J tube). Therapeutic drug monitoring was performed to ensure appropriate absorption. Peak and trough concentrations were measured in the early and late phases of the treatment course and resulted in trough levels of 2.7 mcg/mL and 4.0 mcg/mL, which is consistent with previously published trough concentrations of isavuconazole when the capsule was administered intact. This case report suggests that opening isavuconazole capsules and administration through a G-J tube results in appropriate absorption and serum drug levels comparable to intact capsules.