A review of drug patch testing and implications for HIV clinicians

Abstract

Systemic drug-induced hypersensitivity reactions (HSRs) have been reported for a variety of drugs, and are thought to have a combined immunological, genetic and metabolic basis. These diverse idiosyncratic reactions are both drug and host dependent, and subsequent rechallenge with the drugs responsible can result in a potentially life-threatening clinical reaction.Hypersensitivity has been observed in regard to several drugs used to manage HIV and associated infections, with the antiretrovirals nevirapine and abacavir being the best characterized of the syndromes. These events represent a high cost both to the patient and the healthcare system, and those labelled as being hypersensitive to one or both drugs may find their treatment options significantly reduced.The identification of HSRs can be challenging due to the heterogeneity of their clinical manifestations. Furthermore, with multidrug regimens - common in HIV management - it may be difficult to identify the drug responsible. Epicutaneous patch testing, a procedure well established in contact dermatitis, has also been used as a supplementary diagnostic test for several drug-related HSRs; its usefulness, however, depends on both the drug and syndrome involved. This study discusses HSRs and the application of patch testing to their investigation, with particular emphasis on HIV and abacavir - the antiretroviral with which patch testing has been most studied