A 49-year-old homeless man comes to the emergency department because of fatigue, cough, and worsening shortness of breath for 2 weeks. He was diagnosed with HIV-infection 25 years ago but has never had any symptoms. He has always refused to take antiretroviral medication. Pulmonary examination shows diffuse crackles over bilateral lower lung fields. An x-ray of the chest shows diffuse, symmetrical interstitial infiltrates. A trimethoprim-sulfamethoxazole is initiated and the physician discussed the need to resume antiretroviral therapy. Therefore, HIV genotyping assay is performed. Additional testing for HLA-B*57:01 yields positive results. Which of the following medications is contraindicated in this patient due to the risk of a potentially fatal hypersensitivity reaction?

Question

A 49-year-old homeless man comes to the emergency department because of fatigue, cough, and worsening shortness of breath for 2 weeks. He was diagnosed with HIV-infection 25 years ago but has never had any symptoms. He has always refused to take antiretroviral medication. Pulmonary examination shows diffuse crackles over bilateral lower lung fields. An x-ray of the chest shows diffuse, symmetrical interstitial infiltrates. A trimethoprim-sulfamethoxazole is initiated and the physician discussed the need to resume antiretroviral therapy. Therefore, HIV genotyping assay is performed.  Additional testing for HLA-B*57:01 yields positive results.  Which of the following medications is contraindicated in this patient due to the risk of a potentially fatal hypersensitivity reaction?

Quizplus · Accepted Answer

Eductional Objective: Abacavir hypersensitivity reaction (AHR) is an allergic reaction that develops in 2%-8% of patients and is strongly associated with the HLA-B*57:01 allele of the human leukocyte antigen (HLA) system. AHR occurs due to direct binding of abacavir to a segment on the HLA-B*57:01 molecule, which alters the presentation of self-peptides to the immune system and results in a delayed hypersensitivity reaction (type IV).

A 49-Year-Old Homeless Man Comes to the Emergency Department Because