Isentress works well in untreated HIV patients

US drug major Merck & Co's Isentress (raltegravir) in combination with two other HIV drugs reduced viral load to undetectable levels in 83% of previously-untreated patients, comparable to Bristol-Myers Squibb's Sustiva (efavirenz) given as part of the same regimen, according to data presented at the 2008 International AIDS Conference, held in Mexico City.

Merck noted that patients taking its first-in-class integrase inhibitor experienced a mean increase in CD4 cell counts of 221 cells/mm3 without adverse impact on total or low-density lipoprotein cholesterol, or triglycerides (exploratory endpoints).

The use of the drug in this setting is investigational. It is approved in combination with other antiretrovirals for treatment-experienced patients with evidence of HIV-1 replication despite ongoing therapy. This indication is based on analyses of plasma HIV-1 RNA levels up through 24 weeks in two controlled studies of Isentress. "These findings are consistent with the efficacy and safety data seen with Isentress in treatment-experienced patients," said Martin Markowitz, lead study investigator. "Viral load reductions were sustained through 96 weeks in this study, the longest conducted to date with Isentress," he added.