A 46-year-old HIV-positive man is doing poorly on his antiretroviral regimen. He undergoes HIV genotyping and begins a new treatment regimen. Several days later, he follows up for routine blood work and reports feeling well with no adverse reactions. Blood work reveals a creatinine of 1.6 mg/dL (baseline 1.0 mg/dL), and a urinalysis shows hematuria, pyuria, and crystalluria.
Which of the following medications is most likely responsible?
A. TenofovirIndinavir. Crystal nephropathy is a potential adverse reaction of indinavir, a protease inhibitor used in the treatment of HIV. Other protease inhibitors can cause crystalluria, but indinavir has a high incidence of this complication. Additional medications that can cause crystal nephropathy include methotrexate, acyclovir, and ethylene glycol. (A) Tenofovir is a nucleoside reverse transcriptase inhibitor (NRTI) that can cause renal failure, but the mechanism is not by crystal formation within the tubules. (B) Abacavir is another NRTI that has a high incidence of life-threatening hypersensitivity reactions, especially in patients who are HLA-B*5701 positive. (D) Efavirenz is nonnucleoside reverse transcriptase inhibitor (NNRTI) that causes depression and other CNS effects. (E) Maraviroc antagonizes CCR5 and inhibits entry of HIV into host cells; it can cause hepatotoxicity. Didanosine is an NRTI, and like other NRTIs it may cause lipodystrophy and lactic acidosis.