NEW YORK (CNNMoney.com) -- The Food and Drug Administration Wednesday approved the first once-daily pill for fighting AIDS, according to the the drug's makers, Bristol-Myers Squibb and Gilead Sciences.

Atripla, which treats HIV, the virus that causes AIDS, is a combination of Bristol-Myers' (down $0.40 to $25.08, Charts) Sustiva and Gilead's (up $0.03 to $61.79, Charts) Truvada, two other drugs that fight the virus. Truvada itself is a combination of two other drugs.

"You're getting the first and only medication to contain a complete triple-drug once-daily cocktail contained in a single tablet," Bristol-Myers spokesman Eric Miller said in a phone interview.

The development of Atripla is important because it simplifies treatment for AIDS patients, who have had to take complex drug "cocktails" that included many pills a day. Miller said that 10 years ago, HIV patients took as many as 25 pills a day, staggered at different times throughout the day.

Though Atripla is the first HIV drug that can be taken alone as a single-pill regimen, it also can be combined with other drugs, depending on the needs of the patient, said Miller.

The consolidation of various compounds into one drug, Atripla, has been a decade in the making.

"The availability of Atripla marks the culmination of 10 years of efforts to simplify dosing while helping to achieve and maintain effective viral suppression for adults infected with HIV-1," Dr. John Bartlett, an HIV expert with Johns Hopkins University, said in a statement.

There are more than 38 million people living with AIDS worldwide, with two-thirds of them in sub-Saharan Africa, according to the United Nations. The agency estimates there are about 4 million new infections and nearly 3 million deaths every year.

The market for AIDS drugs worldwide is at least $4 billion, but it's capped by the fact that drugmakers give much of the product to poor Africans for free. GlaxoSmithKline (down $1.21 to $55.25, Charts) is the industry leader with eight HIV drugs on the market, including Combivir, a combination of two drugs.

The FDA approval is important to Bristol-Myers and Gilead, because they have the rights to promote the drug in the U.S., as well as Canada and parts of Europe. Merck (down $0.57 to $36.70, Charts) has the right to approve the drug in other countries, including Africa, the Middle East, and parts of Europe and Asia.

Pending regulatory approval in those nations, Merck would also supply the drugs through the UN and the President's Emergency Plan for AIDS Relief, a U.S. government initiative, said Merck spokesman Ray Kerins.

Andrew McDonald, analyst for ThinkEquity Partners, said in a note that the development of Atripla should help boost Gilead stock to about $76 a share, from about $61 now, over the next 12 months.

"This landmark event, which comes 25 years into the AIDS epidemic, represents a significant growth opportunity for Gilead as the company further entrenches itself as the leader in the treatment for HIV," he wrote.

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