Successful application of pharmacogenomic testing in the evaluation and management of a patient with human immunodeficiency virus and disseminated histoplasmosis.

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.