have submitted an application to European regulators in an effort to gain approval for the HIV drug Atripla.
The once-daily pill combines efavirenz, sold under the Bristol trade name Sustiva, emtricitabine, known by the Gilead brand name Emtriva, and tenofovir, sold by the Gilead name Viread.
Atripla is already approved in the U.S. to treat HIV. The two drugs, Emtriva and Viread, are also prescribed as a once-daily combined tablet known as Truvada. Efavirenz is sold in a number of countries by Merck under the name Stocrin.
The European application for Atripla was filed jointly by the three companies through a new three-way joint venture based in Ireland.
Bristol's shares fell 1% to $24.18, Merck's stock was 0.5% lower to $41.66, and Gilead dipped 0.8% to $64.82.