Low itraconazole serum concentrations following administration of itraconazole suspension to critically ill allogeneic bone marrow transplant recipients

OBJECTIVE: To report itraconazole serum concentrations following administration of itraconazole suspension via orogastric feeding tubes to 2 critically ill allogeneic bone marrow transplant recipients. CASE SUMMARIES: A 38-year-old man and a 29-year-old man, each allogeneic bone marrow transplant recipients, were treated with oral itraconazole for documented fungal infections. Intubation and mechanical ventilation impeded ingestion of itraconazole capsules. Itraconazole was prepared initially as a suspension in intravenous lipid emulsion 20% and later as a suspension in citric acid 1.5% in D5W USP. Itraconazole serum concentrations were assayed using HPLC. Predose itraconazole serum concentrations were undetectable to 72 ng/mL. Postdose itraconazole serum concentrations were 5-97 ng/mL. Itraconazole concentrations measured in these patients were markedly lower than serum concentrations reported in the literature for similar doses administered to fed subjects. DISCUSSION: Efficacy of this antifungal agent is limited currently by the patient's ability to ingest and absorb the itraconazole capsules. Pathophysiologic factors and suspension formulation issues that likely contributed to decreased itraconazole absorption are discussed. CONCLUSIONS: Preparation and administration of itraconazole as a suspension did not enhance drug absorption in these patients. Furthermore, efficacy of itraconazole suspension may be affected by physical compatibility and chemical stability of the extemporaneous preparations.