Abacavir label updated in the US on use of B-5701 testing and cardiovascular risk

On July 22, 2008 the U.S. Food and Drug Administration (FDA) approved changes to the prescribing information for abacavir (Ziagen). The newly added information recommends taking into consideration two separate factors in prescribing decisions: patients’ HLA-B*5701 allele status and underlying heart disease risk factors when prescribing antiretroviral therapies including abacavir.

Screening for the HLA-B*5701 allele is recommended for any patient prior to initiating HIV treatment with abacavir, or prior to reinitiation of it in patients who have previously tolerated abacavir but whose HLA-B*5701 status is unknown and abacavir-containing regimens should not be used by any patient that screens positive.

Label changes relating to cardiovascular risk refer to the findings of the prospective, observational, epidemiological study, D:A:D Study published in the April 26, 2008 issue of The Lancet. Results of this study of over 30,000 patients suggest that current or recent use (within the past 6 months) of abacavir may be associated with a potential 2-fold increased risk of myocardial infarction, that had the highest clinical significance in patients with high underlying cardiovascular risk.

Also included in the label is a pooled analysis of GSK-sponsored clinical trials involving abacavir and found no relationship between use of abacavir and increased risk of myocardial infarction. This analysis included a total of almost 10,000 patients receiving abacavir. The labeling states that in totality, the available data from the observational cohort and clinical trials are inconclusive.