After which phase of the drug approval process does a company file a New Drug Application (NDA) to sell the drug on the market?

The correct answer is linked to the importance of Phase 3 testing in the drug approval process. Before a pharmaceutical company can market a new drug, it must conduct rigorous clinical trials to ensure safety and efficacy. Phase 3 testing is the final stage of clinical trials where the drug is tested on a large population to confirm its effectiveness and monitor side effects.

Successful completion of Phase 3 provides substantial evidence that the drug is both safe and effective for the intended use. Once this phase is concluded, the data collected is compiled into a New Drug Application (NDA), which is then submitted to the Food and Drug Administration (FDA) for review. This step is critical as the NDA serves as a formal proposal to the FDA for approval to market the drug. If the NDA is approved, the company is granted the ability to sell the drug commercially.

Understanding this sequence highlights the regulatory pathway that ensures drugs meet necessary safety and efficacy standards before reaching the public.