The boxed warning for GlaxoSmithKline's Ziagen (abacavir sulfate) and other abacavir-containing drugs has been updated to warn about the increased risk of serious or fatal hypersensitivity reactions (HSR) in patients with the human leukocyte antigen allele, HLA-B*5701. Labeling changes recommend that patients be screened for the HLA-B*5701 allele before starting or restarting abacavir-based therapy and abacavir treatment should be avoided in positive patients. Development of clinically-suspected abacavir HSR requires immediate and permanent discontinuation of abacavir therapy, including patients negative for HLA-B*5701.

The labels for GlaxoSmithKline’s Trizivir (abacavir sulfate/lamivudine/zidovudine) and Epzicom (abacavir sulfate/lamivudine) will also be updated.

Abacavir, a nucleoside analogue, in combination with other antiretroviral agents, is indicated for the treatment of HIV-1 infection.

For more information visit www.fda.gov/medwatch/safety/2008/safety08.htm#Abacavir.