In the US, FDA approval is usually sought after which phase's success?

• A. Phase 3
• B. Phase 2
• C. Phase 4
• D. Phase 1

Answer: (A)

The test is about when regulators get enough evidence to grant approval. In the US, the FDA relies on strong, pivotal evidence from late-stage trials to determine safety and efficacy. That means the large, well-controlled studies that follow early safety and dosing work—phase three. These trials involve more patients and aim to confirm that the drug works for its intended use and to characterize risks in a diverse population. When phase three results are favorable, a sponsor files for FDA approval, presenting the substantial evidence needed to weigh benefits against risks. Phase one and two mainly establish safety, dosing, and early signals of effectiveness, while phase four occurs after approval to monitor long-term safety in the real world. So approval is usually sought after success in phase three.