What is the definition of Phase 2 in clinical trials?

Phase 2 in clinical trials is characterized by testing a small group of individuals who have the disease or condition that the new intervention is designed to treat. This stage follows Phase 1, where the primary objective is to assess the safety and tolerability of the drug in a small group of healthy volunteers. In Phase 2, the focus shifts to observing the drug's efficacy against the specific disease, along with continued safety monitoring.

By recruiting a small group of patients with the disease, researchers can determine the optimal dosage and refine the methods to evaluate the drug's effectiveness. This phase is critical as it provides essential data on the therapeutic outcomes for the target population, setting the stage for Phase 3 trials, which involve larger groups and further evaluation of both effectiveness and adverse effects.

The other options described refer to different stages or contexts in clinical research. Assessing a large group of individuals with the disease corresponds to Phase 3 trials, testing safety in healthy individuals aligns with Phase 1, and post-marketing assessments are conducted after a drug is approved for use, which does not apply to Phase 2.