Phase II typically starts with initiation of studies in which population?

• A. In patients
• B. In healthy volunteers
• C. In animals
• D. In retired volunteers

Answer: (A)

Phase II trials are designed to evaluate preliminary efficacy and continue safety assessment in people who actually have the disease or condition the drug is intended to treat. After Phase I establishes safety in a small number of healthy individuals, testing for whether the drug works and what dose ranges are effective is performed in patients with the target condition. This is because efficacy needs to be demonstrated in the population that would use the therapy, and Phase II helps identify the right dose while monitoring adverse effects in that group. Testing efficacy in healthy volunteers or in animals wouldn't provide the relevant information about therapeutic benefit in patients, and retired volunteers aren’t a study population for this purpose. Therefore, initiation occurs in patients.