US regulators on Monday approved Truvada, made by Gilead Sciences in California, for use as the first pill to help prevent HIV in some at-risk groups, the US Food and Drug Administration said. "Truvada is to be used for pre-exposure prophylaxis (PrEP) in combination with safer sex practices to prevent sexually-acquired HIV infection in adults at high risk. Truvada is the first drug approved for this indication," it said. Truvada has been on the US market since 2004 as a treatment for people infected with HIV to be used in combination with other antiretroviral drugs. An FDA advisory panel in May urged the approval of Truvada for prevention when taken in uninfected people after clinical trials showed Truvada could lower the risk of HIV in gay men by 44 to 73 percent. The pill has been hailed by some AIDS advocates as a potent new tool against human immunodeficiency virus, but some health care providers are concerned it could encourage risky sex behavior.