Successful application of pharmacogenomic testing in the evaluation and management of a patient with HIV and disseminated histoplasmosis

Abstract Objectives To demonstrate the successful use of pharmacogenomic testing to specifically tailor antifungal treatment to the phenotype of a patient with human immunodeficiency virus (HIV) and disseminated histoplasmosis who had clinical progression while on itraconazole and subsequently had insufficient therapeutic drug levels of voriconazole. Case summary We present the case of a patient with HIV and disseminated histoplasmosis with a persistently elevated serum Histoplasma capsulatum antigen and subtherapeutic levels of voriconazole. Pharmacogenomic testing revealed he was a CYP2C19 rapid metabolizer, thus explaining his persistent, subtherapeutic levels of voriconazole and prompting a change in therapy. Practice implications Our case illustrates the importance of pharmacogenomic testing as a tool to evaluate subtherapeutic itraconazole or voriconazole levels, especially in patients with failed clinical or Histoplasmosis Ag response despite reporting full adherence to prescribed therapy.