Developed by US pharmaceutical giant Merck and Co, Isentress is the first of a new type of anti-AIDS medication called HIV integrase inhibitor, based on the enzyme that controls HIV virus reproduction.
The study's Phase III clinical trials -- the last step before an approval request can be submitted to the Food and Drug Administration (FDA) -- showed Isentress reduced HIV viral load to undetectable levels in 86 percent of patients, against only 82 percent treated with efavirenz, an older anti-HIV medication also developed by Merck.
Drug-related adverse effects were also significantly fewer in patients treated with Isentress (44 percent) than with efavirenz (77 percent), the researchers told the 48th annual Interscience Conference on Antimicrobial Agents held this weekend in Washington.
Patients taking part in the clinical trial also took tenofovir and emtricitabine in combination with Isentress and efavirenz, Merck said in a statement.
On October 12, 2007, the FDA granted Isentress accelerated approval for use with patients that showed initial signs of resistance to existing anti-retroviral treatment, a common problem among AIDS patients.
Merck estimates that among some 500,000 US patients treated with anti-HIV cocktails, up to 40 percent have developed resistance to treatment.
Industry analysts said treatment with Isentress pills twice a day could bring Merck one billion dollars in sales over the next three years, competing directly with rival Gilead Sciences' elvitegravir, also undergoing clinical trials.
A separate study presented at the ICAAC conference showed anti-retroviral treatment was more effective if begun earlier: patients treated when CD4 cell count was at 500 had a 71 percent greater risk of dying than those treated when CD4 levels reached 350.
According to the World Health Organization, 33 million people around the world are infected with the AIDS virus, mostly in the sub-Sahara Africa. One million HIV-infected people live in the United States.
Some two million people died worlwide of AIDS in 2007.