Gilead Sciences on Thursday said preliminary data from a 48-week trial show that two of its two drugs, Viread and Emtriva, were better able to control levels of HIV than Combivir, a popular treatment sold by GlaxoSmithKline Plc.

Gilead said it hopes U.S. regulators will allow it to use the successful data as a means of better competing against Combivir and other medicines that treat the virus that causes AIDS.

The Phase III trial involved almost 500 patients who had not previously been treated for HIV.

After 48 weeks of treatment, Gilead said those taking Viread and Emtriva once daily along with a once-daily HIV treatment called Sustiva (efavirenz) sold by Bristol-Myers Squibb Co. significantly better controlled the virus than those who took Combivir twice daily along with Sustiva.

Viread and Emtriva are Gilead drugs that are combined in the company’s recently approved new pill, Truvada, which is taken once daily, along with other HIV drugs. It works by blocking reverse transcriptase, an enzyme that HIV requires for replication.

Gilead, which reported similar results last summer after six months of trial data had been analyzed, said it hopes to eventually include the 48-week data on the drug labels of Truvada, Viread and Sustiva.

“That would allow our sales force to use the data for promotional purposes,” said Gilead spokeswoman Amy Flood.

Combivir itself includes two HIV drugs, Epivir - also known as lamivudine and 3TC - and Retrovir, also known as AZT and zidovudine. They are members of the HIV class of medicines called nucleoside reverse transcriptase inhibitors.

Drugmakers increasingly are combining HIV drugs into single pills to free HIV patients from the complications of having to take a wide range of medicines at different times of the day.

Gilead and Bristol-Myers in December formed a U.S. joint venture to develop and sell a once-daily tablet containing Viread, Emtriva and Sustiva. All three drugs belong to another class of HIV treatments called non-nucleoside reverse transcriptase inhibitors.

The Glaxo trial will continue another year for patients who opt to continue in the study, to allow Gilead to collect more information about the comparable safety and efficacy of its drugs.

Gilead said Viread had 2004 global sales of $783 million. Emtriva had sales of $58 million, while Truvada garnered $68 million.