Drugmaker Gilead Sciences announced Tuesday that preliminary results from a bioequivalency study of a fixed-dose pill containing its combination anti-HIV drug Truvada with Bristol-Myers Squibb's HIV treatment Sustiva show the first attempt to combine the drugs has failed, TheStreet.com reports. The formulation resulted in levels of Sustiva in the bloodstream below that seen when dosing Sustiva separately, Gilead officials say. Gilead and BMS in December announced an effort to create the first one-pill, once-daily, three-drug HIV treatment by combining Gilead's Truvada--which contains the two separate drugs Viread and Emtriva--and BMS's nonnucleoside reverse transcriptase inhibitor Sustiva. The resulting combination pill would be the simplest triple-drug regimen ever available in the United States. Gilead says it is going to begin a second study with another formulation. The companies, in announcing the joint effort, had said they hoped to have an effective combination pill developed and submitted to the Food and Drug Administration for approval by the end of 2005.