The US Food and Drug Administration (FDA) has given the green light to market Truvada as a drug that can reduce the risk of HIV infection. It would be aimed at people who are at high risk, such as those whose partner is HIV-positive.
Travuda was originally approved by the FDA in 2004 as a drug treatment for people infected with the virus, which leads to AIDS.
It was developed by the US pharmaceutical company, Gilead Sciences.
Following the recommendation of a committee of independent experts in May, the FDA has now approved the drug as a preventative measure.
"Today's approval marks an important milestone in our fight against HIV," says FDA Commissioner, Margaret Hamburg.
In one trial, involving heterosexual couples, in which one partner was HIV-infected, Truvada is said to have reduced the risk of further infection by 75 percent.
In another trial, involving homosexuals, the drug apparently reduced the risk of infection by 73 percent.
But critics warn that Truvada will not offer protection for everyone.
The drug is also expensive. It costs up to $14,000 (11,440 euros) per year.
Doctors warn that HIV could develop a resistance to the drug.
There are more than two dozen drugs on the market which people living with HIV can use to slow or protect against the occurrence of AIDS.
At least three active agents have to be combined to prevent AIDS from developing. And one of the key benefits of Truvada is that the drug contains two of the three required agents.
Travuda is taken once daily. Jürgen Rockstroh from Bonn University Hospital says it is easier to digest and tolerate than other drugs.
But current studies show the drug can only provide protection for non-infected people - and treatment for those who are infected - if taken daily. It is said to be ineffective if used sporadically - for instance, just before or just after sex.
Potential side effects
Stefan Esser, director of the HIV unit at Essen's University Hospital says there are side effects as well - as with many drugs.
These include reduced bone density and deteriorated kidney function.
It is expected that European physicians will oppose the drug's approval here because of the side effects.
The FDA approval comes ahead of an International AIDS Conference in Washington.
More than 25,000 experts will discuss their efforts to tackle the spread of HIV/AIDS and present new research on preventive and curative measures.
Author: Martin Winkelheide / jrb
Editor: Zulfikar Abbany