First Gilead/BMS drug combo pill fails, second to be studied

A bioequivalence study is required to demonstrate that a co-formulated product results in the same levels of medication in the blood as achieved when the individual products are dosed simultaneously as separate pills. Preliminary results from the bioequivalence study of the first formulation indicate that efavirenz levels in the blood are lower than those achieved with the recommended 600mg dose of Sustiva (efavirenz) alone.

Based on improvements in formulation as well as data from preclinical studies, Gilead believes the next-generation formulations are likely to achieve higher levels of efavirenz in the blood than those achieved with the first formulation. If the second formulation is proven to be bioequivalent to the products dosed simultaneously as separate pills, the companies could submit a new drug application requesting marketing approval of the fixed-dose combination to the FDA before the end of 2005.

If approved, the Truvada (emtricitabine and tenofovir disoproxil fumarate) and Sustiva combination product would be the first complete highly active antiretroviral therapy (HAART) treatment regimen for HIV available in a fixed-dose combination taken once daily. The joint venture established by the two companies is the first of its kind in the field of HIV therapy.

Gilead said that it will initiate a bioequivalence study in humans and stability studies of the second formulation shortly and, in addition, is evaluating several different alternative formulations.