A New Drug Application (NDA) is a request submitted to the United States Food and Drug Administration (FDA) by a drug manufacturer for approval to market a new or previously unapproved drug in the United States. The NDA contains all the necessary information about the drug, including its pharmacological properties, clinical data, safety information, manufacturing details, and proposed labeling.

The NDA process involves multiple steps, including preclinical studies, clinical trials, and a rigorous review by the FDA. The FDA typically takes several months to review an NDA and may request additional information or clarification from the drug manufacturer before making a final decision.

Once approved, the drug can be legally marketed in the United States for its intended use and is given a unique identification number. The drug manufacturer is also responsible for ongoing monitoring of the drug's safety and effectiveness and must report any adverse events to the FDA.

The NDA process is critical in the healthcare industry, as it is the primary mechanism through which new drugs are evaluated for safety and efficacy. It ensures that only drugs that have undergone rigorous testing and meet the FDA's standards for safety and effectiveness are available to patients. It also plays an important role in controlling healthcare costs by reducing the likelihood of harmful or ineffective drugs being prescribed.