Which phase uses healthy volunteers to test safety and dosage?

• A. Phase II
• B. Phase I
• C. Phase III
• D. Phase IV

Answer: (B)

Early human testing focuses on safety and dosing. In this stage, healthy volunteers are typically used to minimize risk while researchers evaluate how the drug behaves in the body and what doses people can tolerate. The goals are to establish a safe dose range, identify common side effects, and collect pharmacokinetic data such as absorption, distribution, metabolism, and excretion. Because the emphasis is safety rather than efficacy, researchers often reserve this phase for healthy individuals unless disease-specific risks make it inappropriate. Once safety and dosing are understood, trials proceed to patients with the condition to assess effectiveness and optimal dosing in real-world use, followed by larger confirmatory studies and post-marketing surveillance.