Abacavir

It is a guanosine analog. There may be some cross-resistance with strains resistant to AZT and lamivudine. Abacavir is well absorbed orally, and metabolites appear in the urine Most of the drug is metabolized by non-CYP450–dependent reactions. A carboxylic acid derivative and a glucuronidated form have been identified. Common side effects include GI disturbances, headache, and dizziness. Approximately 5 percent of patients exhibit the “hypersensitivity reaction,” which is usually characterized by drug fever, plus one or more of the following symptoms of rash, GI symptoms, malaise, and respiratory distress Sensitized individuals should never be re-challenged because of rapidly appearing, severe reactions that lead to death. There is a newly approved HLA genetic test available to screen patients for the potential of this reaction. an intracellular half-life of 12–24 h