5th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 8–11 July 2003, Le Meridien Montparnasse, Paris, France

DIAGNOSIS OF ABACAVIR HYPERSENSITIVITY REACTIONS AMONG PATIENTS NOT RECEIVING ABACAVIR IN TWO BLINDED STUDIES

Antiviral Therapy 2003; 8:L88 (abstract 134)

J Hernandez, A Cutrell, T Bonny, S Castillo, C Brothers, J Hee, W Powell and T Scott
GlaxoSmithKline, Research Triangle Park, NC, USA

AIM/METHODS: Abacavir is a potent nucleoside analogue, generally safe and well tolerated by most HIV-infected individuals. A hypersensitivity reaction of unknown cause is reported in approximately 5% of subjects receiving abacavir in controlled clinical trials. To assess the frequency and clinical characteristics of subjects diagnosed as having a hypersensitivity reaction to abacavir in control arms of double-blinded studies, we performed a retrospective review of two studies conducted in antiretroviral therapy-naïve HIV 1-infected adults starting lamivudine/zidovudine + indinavir or lamivudine + zidovudine + efavirenz. All subjects also received placebo resembling abacavir. Records were analysed for the occurrence of serious adverse events and diagnoses of hypersensitivity reactions.

RESULTS: Two-hundred-and-sixty-five subjects (median age 36 years, 86% male, 75% white) started lamivudine/zidovudine + indinavir with abacavir placebo (CNA3005). Median plasma HIV-1 RNA was 4.82 log₁₀ copies/ml; median CD4 cell count was 360 cells/mm³. Three-hundred-and-twenty-five subjects (median age 35 years, 82% male, 51% white) started zidovudine + lamivudine + efavirenz with abacavir placebo (CNA30024). Median HIV-1 RNA was 4.79 log₁₀ copies/ml; median CD4 cell count was 258 cells/mm³. Six subjects not receiving abacavir were diagnosed by investigators as having abacavir hypersensitivity reactions in CNA3005 [rate 2% (6/265)], and ten in CNA30024 [rate 3% (10/325)]. In most cases, either rash alone or rash or fever plus non-specific symptoms were reported. None of these cases were considered abacavir hypersensitivity reactions after an internal partially blinded medical review. One case was considered life-threatening and two were hospitalized (CNA30024).

CONCLUSIONS: Diagnosis of hypersensitivity reaction to abacavir occurred in 2 to 3% of subjects not receiving abacavir in double-blinded studies. Most cases had rash alone or rash accompanied by non-specific, mild symptoms. These data underscore the importance of assessing hypersensitivity reactions to abacavir as a multi-symptom syndrome and suggest that hypersensitivity reactions to abacavir may be overdiagnosed, particularly in the presence of rash due to other agents. However, when a distinction cannot be made, abacavir should be discontinued.

Presenting author: J Hernandez

2003-07-08
134

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