Enfuvirtide (INN)'s an HIV fusion inhibitor, the first of a novel class of antiretroviral drugs used in combination therapy for the treatment of HIV-1 infection. It's marketed under the trade name Fuzeon (Roche). Enfuvirtide therapy costs an estimated USD$25,000 per year in the United States. Its cost and inconvenient dosing regimen are factors behind its use as a reserve, for "salvage" therapy in patients with multi-drug resistant HIV. Structural formula Ac-Tyr-Thr-Ser-Leu-Ile-His-Ser-Leu- Ile… (More on Enfuvirtide)