Abacavir hypersensitivity

Abacavir is a nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV infection, in combination with other medications, as part of highly active antiretroviral therapy. Although abacavir is generally well tolerated, ~5–8% of patients experience a hypersensitivity reaction (HSR) during the first 6 weeks of treatment. Suspicion of an HSR requires immediate discontinuation of abacavir. Drug re-challenge is contraindicated because immediate life-threatening reactions can occur. HLA-B is a member of the major histocompatibility complex gene family and patients with at least one HLA-B*57:01 allele may develop HSR when treated with abacavir. HLA-B allele status has no effect on abacavir pharmacodynamics or pharmacokinetics; it only influences the likelihood that an HSR will occur. Guidelines regarding the use of pharmacogenomic tests in dosing for abacavir have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website.

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