Racivir is an experimental anti-HIV drug which belongs to the class of drugs known as nucleoside analogue reverse transcriptase inhibitors (NRTIs). These drugs interfere with the process of viral replication within cells to reduce the amount of HIV in the blood.

Racivir is being produced by Pharmasset, a pharmaceutical company based in Georgia, United States.

Racivir is a cytosine analogue, closely related in structure to FTC (emtricitabine, Emtriva) and like that drug, it is also active against hepatitis B. It has been proposed as an agent that will be active against hepatitis B that is resistant to 3TC (Epivir). Racivir is also closely related to D-D4FC, another NRTI being developed by Pharmasset Pharmaceuticals.

In a phase I / II dosing and efficacy study, racivir was administered at three doses (200, 400 or 600mg once daily) in combination with d4T (stavudine, Zerit) and efavirenz (Sustiva). Six HIV-positive individuals were recruited to each dosing group. After day 15, treatment was discontinued and viral load continued to be monitored until day 35. Viral load had declined by an average of 2.02 to 2.42 log₁₀ by day 14, and remained more than 2 log₁₀ below baseline at day 28 at all doses. Rebound above this level began to be detected by day 35, but viral load still remained more than 1 log₁₀ below baseline at this point (Otto 2003).

Reference

Otto MJ et al. Sustained anti-HIV-1 effect of racivir combined with d4T and Sustiva following a 14-day treatment of infected volunteers. Tenth Conference on Retroviruses and Opportunistic Infections, Boston, abstract P552, 2003.