Enteral Delivery of Posaconazole or Izavuconazole in Patients with Inability to Swallow Tablets Can Achieve Therapeutic Drug Levels: A Single Center Pilot Study

Abstract

<h3>Purpose</h3> One of the most common challenges facing the transplant population are invasive fungal infections including aspergillosis, mucormycosis, and those due to endemic fungi. Fungal prophylaxis is becoming standard of practice to limit development of invasive fungal infections. Isavuconazole and posaconazole are commonly used antifungal medications as both prophylaxis and treatment. These drugs are approved for oral and intravenous (IV) administration however, use via alternative enteric routes have not been well studied. <h3>Methods</h3> A retrospective chart review was conducted of transplant patients receiving triazole therapy for prophylaxis or treatment over a seven month period. Patients with an inability to swallow oral medications switched during their course of care from IV therapy to non-oral enteric administration of isavuconazole or posaconazole via nasogastric, orogastric, percutaneous endoscopic gastrostomy (PEG), or percutaneous endoscopic gastrojejunostomy (PEG-J) tubes were included in the study. <h3>Results</h3> We identified 17 patients administered isavuconazole or posaconazole via non-oral enteric routes (Table 1). The indication for therapy was primarily for prophylaxis after single or double lung transplantation. The majority (83%) of cases were therapeutic at the time of their first drug level assessment, with a mean level of 2.47 +/- 0.71 for isavuconazole and 0.84 +/- 1.03 for posaconazole. All patients not therapeutic at initial assessment had doses increased and subsequently achieved therapeutic levels. <h3>Conclusion</h3> Our case series shows isavuconazole and posaconazole can be administered via non-oral enteric routes with therapeutic drug monitoring to achieve acceptable serum drug concentrations and avoid prolonged IV therapy in a transplant population. Given the increasing complexity and age of transplant recipients, continued studies are needed to address alternative antifungal dosing regimens.