3 new drugs for HIV are raising hopes

About 800 patients have participated in clinical trials of Isentress, and an additional 3,500 are receiving the drug free through expanded access, Isaacs said. Isentress is scheduled to go before the U.S. Food and Drug Administration's advisory committee Sept. 5 and could get sales approval by mid-October.

Merck's HIV sales were $327 million in 2006, just 1.5 percent of its $22.6 billion in sales.

Pfizer's Celsentri received a unanimous recommendation for approval from an FDA panel in April, and it is awaiting final FDA action. The drug binds with a receptor on white blood cells and prevents HIV from entering the cell in that way.

But it cannot prevent HIV from using a second receptor that often shows up often late in the disease progression. That means the drug will work in only about half of HIV patients. Those who use Celsentri will need an expensive test to determine if they will be helped.

Etravirine is part of an existing class of drugs, the nonnucleoside reverse transcriptase inhibitors (NNRTIs), which already are facing resistance. But a trial released this month showed that 62 percent of those taking the drug in a cocktail combination had undetectable levels of HIV vs. 43 percent in the comparison group.

Doctors are concerned about the likely high cost of all three drugs when they hit the market. Also, their long-term side effects will not be known until many more people use them.

Still, many doctors say they believe the drugs could take the epidemic into a new phase. "We have three new drugs, all potent," said William Towner, a physician with California-based Kaiser Permanente, which had the largest number of U.S. enrollees in the Etravirine study. "Being undetectable is now a goal again."

Getting the New HIV Drugs

All three new HIV drugs may be available through expanded access programs. But patients must show they can't use existing drugs.

Isentress: Call 1-877-327-6751 or go to http://www.earmrk.com/

Celsentri: Call 1-888-275-4478 or go to http://www.maraviroceap.com/

Etravirine: Call 1-866-889-2074 or e-mail to TMC125EAP@ i3research.com

Sources: Firms