A Phase IIa, Randomized, Double-blind, Active-controlled, 12-week Study of Amdoxovir (Two Doses) Versus Tenofovir DF, in Combination With Zidovudine in HIV-1 Treatment-experienced Subjects With M184I/V Mutation in Addition to 0-2 Confirmed Thymidine Analog Mutations.

This is a double-blind Phase 2a study to test the safety and efficacy of an investigational HIV drug, amdoxovir (300 mg or 500 mg twice daily) compared with tenofovir DF 300 mg once daily in HIV-1 infected antiretroviral therapy-experienced subjects who are currently failing antiretroviral therapy. There are three treatment groups (N=45). Subjects will be randomized to receive either amdoxovir 300 mg twice daily (n=15) or amdoxovir 500 mg twice daily (n=15) or tenofovir DF 300 mg once daily (n=15); each in combination with zidovudine 300 mg twice daily. The study will assess initially amdoxovir (300 mg or 500 mg twice daily) or tenofovir DF 300 mg once daily, both in combination zidovudine 300 mg twice daily plus failing third drug, but then with lopinavir/ritonavir (400 mg/100 mg twice daily) after Week 2. Subjects who received amdoxovir (300 mg or 500 mg twice daily) and benefited from the drug may choose to enroll in the 36-week open-label study.