Phase 1 trial sample size typically ranges from:

• A. 20-80
• B. 100-300
• C. 1000-3000
• D. 50-100

Answer: (A)

In phase 1, the trial is designed to assess safety, tolerability, and how the drug behaves in the body, not to prove efficacy in a large population. To gather meaningful safety and PK/PD data while exposing as few people as possible, these studies stay small. The typical total enrollments are about twenty to eighty participants, often arranged in small cohorts that receive escalating doses. This compact size allows detection of major safety signals and helps establish a starting dose for subsequent phases without the need for large numbers.

Larger ranges like hundreds or thousands of participants belong to later phases where efficacy and broader safety are evaluated, while a range like fifty to one hundred, though sometimes seen, is not the standard ballpark described for most phase 1 trials.