U.S. urges genetic test before using Glaxo AIDS drug

WASHINGTON (Reuters) - AIDS patients should be given a genetic test before treatment with GlaxoSmithKline's (GSK.L: Quote, Profile, Research)(GSK.N: Quote, Profile, Research) drug, Ziagen, to see if they face a higher risk of a potentially fatal reaction, U.S. regulators said on Thursday.

For patients who test positive for a specific gene variation, Ziagen treatment "is not recommended and should be considered only under exceptional circumstances when the potential benefit outweighs the risk," the Food and Drug Administration said in a notice on its website.

Studies have found patients with one specific version of an immune system gene had a higher chance of a serious and sometimes fatal reaction to Ziagen, the agency said.

Glaxo funded one study that showed testing for the gene variation reduced the incidence of reactions, company spokeswoman Mary Anne Rhyne said. The drugmaker submitted the information to the FDA and urged that it be added to Ziagen's prescribing instructions, she said.

Ziagen, known generically as abacavir, had 2007 global sales of $218 million (109.5 million pounds). The drug also is a component of Glaxo's Trizivir, Epzicom and Kivexa AIDS drugs, which had more than $1 billion in combined 2007 sales.

(Reporting by Lisa Richwine; editing by Jeffrey Benkoe and Andre Grenon)