What is a known side effect of abacavir?

Abacavir is an antiretroviral medication used in the treatment of HIV infection. One of the well-documented side effects of abacavir is hypersensitivity syndrome, which occurs in a subset of patients who carry the HLA-B*5701 allele. This reaction typically manifests within the first few weeks of starting the medication and can include symptoms such as fever, rash, gastrointestinal symptoms (nausea, vomiting, diarrhea), and respiratory symptoms (cough, sore throat).

The mechanism of hypersensitivity is believed to involve an immune-mediated response, where the drug or its metabolites interact with specific immune cells, resulting in a potentially life-threatening reaction. It is crucial for clinicians to screen patients for the HLA-B*5701 allele before initiating therapy with abacavir to minimize the risk of this serious adverse effect.

In contrast to the other choices, Stevens-Johnson syndrome is associated more commonly with other classes of medications, lactic acidosis is a known side effect of nucleoside reverse transcriptase inhibitors (NRTIs) such as didanosine and stavudine, and crystal-induced nephropathy is typically associated with certain other medications or conditions rather than abacavir. Thus, hypersensitivity syndrome is the most