Isentress cuts viral load in untreated patients

US drug major Merck & Co's Isentress (raltegravir) reduced HIV viral load to undetectable levels in 86% of patients compared to 82% for those on rival drug efavirenz in previously-untreated HIV patients at 48 weeks.

The US drug major hopes that the data from the late-stage trial will expand the market for its first-in-class integrase inhibitor. Analysts have forecast peak annual sales of up to $1.0 billion for the drug by 2012.

According to findings presented at the 48th annual Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington DC, USA, patients taking Isentress had a greater increase in CD4 cell counts, an average rise of 189cells/mm3, compared to subjects taking efavirenz who had an average increase of 163cells/mm3 at week 48.