Phase I clinical trials are typically conducted with which group?

• A. A large multinational trial in patients.
• B. Healthy volunteers only.
• C. Animal subjects.
• D. A small group of healthy individuals to test safety and dosage levels.

Answer: (D)

Phase I trials focus on safety and how the drug behaves in the body, so they’re done in a small, carefully monitored group to establish safe dose ranges and initial pharmacokinetics. Typically this means a small number of healthy volunteers, which helps researchers evaluate safety and how the drug is absorbed, distributed, metabolized, and excreted before testing in larger patient groups. There are exceptions, such as cancer drugs, where patients with the disease may participate in Phase I to assess safety in the target population, but the standard approach aims to gather foundational safety data first. Large, multinational trials in patients occur later in Phase III to test efficacy, and animal studies precede human trials as preclinical work. That’s why this option—a small group of healthy individuals to test safety and dosage levels—best fits Phase I.