What is the primary purpose of a New Drug Application (NDA)?

The primary purpose of a New Drug Application (NDA) is to market a new drug upon FDA approval. This application is a formal request submitted to the U.S. Food and Drug Administration that includes substantial evidence of the drug's safety and efficacy based on the results of clinical trials. It is the culmination of the drug development process where all the data collected during clinical trials, as well as manufacturing information, labeling proposals, and any additional relevant information, is submitted for review.

Once approved, the NDA allows the pharmaceutical company to sell the drug in the U.S. market, thus making it available for doctors to prescribe and patients to use. This step is crucial because it signifies that the FDA has reviewed the product and found it to meet the necessary standards for safety, efficacy, and quality. Other options such as requesting approval for clinical trials or initiating drug development are parts of the process that take place before an NDA is formulated, making those activities essential but not the primary goal of the NDA itself.