A few specialized issues that should be focused on anti-HIV drug evaluation in vitro.

Since the introduction of antiretroviral therapy (ART), the lifespan and quality of life of patients infected with HIV have been significantly improved. But treatment efficacy was compromised eventually by the development of resistance to antiretroviral drugs, and more new anti-HIV drugs with lower toxicity and higher activity were needed. Based on the experience and lessons learned from the treatment in the developed countries, US FDA suggested that more pharmacodynamical researches should be considered ahead of the clinical trials. To facilitate the anti-HIV drug research and development, we reviewed a few specialized issues that should be focused on drug evaluations in vitro, including: 1) Mechanism of action studies, demonstrating the candidate drug's efficacy to specifically inhibit viral replication or a virus-specific function and confirm the drug target. 2) Drug resistance studies, selecting the drug-resistant variants in vitro and determining the activities inhibiting HIV isolates resistant to approved antiretroviral drugs of the same class. 3) Antiviral activity in vitro in the presence of serum proteins, ascertaining whether an investigational product is significantly bound by serum proteins. 4) Combination activity analysis, evaluating in vitro antiviral activity of an investigational product in two-drug combinations with other drugs approved.