Vicriviroc -: Anti-HIV agent viral entry inhibitor chemokine CCR5 antagonist

Vicriviroc is a viral entry inhibitor under development for the treatment of HIV-1 infection in combination with other antiretrovirals. It is a small-molecule antagonist of the chemokine receptor CCR5, which is expressed on the surface of macrophages and leukocytes and is required for the efficient entry of R5-tropic HIV into target cells. Vicriviroc has potent activity against a wide range of primary HIV-1 isolates and an excellent pharmacokinetic profile. In a phase II clinical trial, vicriviroc was associated with treatment failures in combination with the reverse transcriptase inhibitors lamivudine/zidovudine (Combivir (R)), whereas in another phase II trial, vicriviroc (10 mg once daily and above) was effective in reducing HIV viral load and increasing CD(4+) counts in combination with optimized background therapies containing ritonavir (which boosts the pharmacokinetics of vicriviroc) and a protease inhibitor.