In an effort to make medication regimens easier for HIV-positive patients, two drug companies have announced plans to collaborate on the first all-in-one, one-a-day pill to treat the infection.

Currently, the best AIDS treatment requires patients to take two to four pills a day. Less than a decade ago, many patients had to take 25 to 30 pills a day, often at precise times and under specific conditions such as with food, making it extremely difficult for patients to stick to the complex schedule. Missing doses makes it easier for the virus to mutate and become resistant to medication.

In the first collaboration by competing AIDS drug makers, Bristol-Myers Squibb Co. and Gilead Sciences Inc. announced Monday that they have formed a joint venture to test and market a single pill combining three widely used medicines.

Because the three individual drugs already are on the market, the once-a-day combination could be approved and on sale as early as the second half of 2006, said David Rosen, a spokesman for Bristol-Myers Squibb.

The combination pill will be made up of Sustiva, made by Bristol-Myers Squibb, and two AIDS drugs made by Gilead Sciences: Viread and Emtriva.

The latter two drugs are members of the same class of AIDS drugs, but they block copying of the AIDS virus at two different points early in its replication cycle. Sustiva is from a different class of drugs and attacks the virus later in the cycle.

The pill is for people diagnosed HIV-positive who have never taken HIV medicines before.
The two companies will have to find a way to combine the component drugs so that the single pill is absorbed the same way, has identical effects, lasts in the body as long and has the same shelf life, said Robert Lipper, vice president of biopharmaceutics research and development at Bristol-Myers.