Washington, Dec. 11 (Reuters): US researchers said yesterday they had established the “best” cocktail of AIDS drugs to start patients on — one that keeps the virus at bay for the longest time with the fewest side effects.

The cocktail includes the oldest HIV drug, GlaxoSmithKline’s AZT, also known as zidovudine; Glaxo’s Epivir, known as lamivudine or 3TC; and Bristol Myers Squibb’s efavirenz, sold under the brand name Sustiva.

The researchers said their government-funded studies, published in the New England Journal of Medicine, were aimed at helping doctors and patients navigate through the maze of 19 HIV drugs.

“These findings offer new insight into the most effective approach for treating previously untreated HIV-infected individuals,” Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a statement.

“Until now, it has been unclear which sequences of antiretroviral regimens provide the greatest benefit to patients previously untreated,” said Dr Gregory Robbins of Massachusetts General Hospital and Harvard Medical School, who led one of the studies.

“Findings from this and similar studies can help reduce some of the guesswork involved,” he added.

Human immunodeficiency virus, which infects 40 million people around the world and 900,000 in the US, is incurable and leads to AIDS.

But a cocktail of drugs called highly active antiretroviral therapy can suppress the virus and keep patients healthy for years.

Eventually one combination stops working and the patients must switch to a new mix. Doctors have been confused about when to start patients on drugs and which cocktail is the most effective. Pharmaceutical companies keep adding drugs to the arsenal.

There are now four classes of HIV drugs on the market, and mixing at least two classes usually works best. They include the protease inhibitors and the non-nucleoside RTIs.

Robbins and colleagues compared four three-drug combinations in 620 patients in the US and Italy over two years.