What is done in phase 2 of drug development?

• A. Healthy volunteers are used to determine the drug tolerance.
• B. Dose-response studies and PKs are performed to determine the optimum dosage regimen; limited number of patients with condition are treated under close supervision.
• C. Market launch planning begins.
• D. Animal pharmacology data are collected.

Answer: (B)

Phase 2 centers on finding the right dose with initial evidence of efficacy in patients who have the condition. This stage uses dose-ranging studies and pharmacokinetic (and pharmacodynamic) measurements to understand how different doses affect response and how the drug behaves in the body. A limited number of patients are treated under close supervision to monitor effectiveness and safety, helping to establish the optimum dosage regimen to carry into phase 3 trials.

This differs from early testing in healthy volunteers, which is focused on tolerability and basic safety; it also comes after animal data and before any market launch, which occurs after larger, confirmatory trials in phase 3.