As noted in the answer to the previous question, data supporting the safety and functionality of an excipient in a drug product is included in data and clinical reports submitted to support a new drug application (NDA). In the case of a new pharmaceutical use for an excipient, it is likely that some necessary data may exist in a confidential drug master file at FDA. However, in all instances involving pharmaceutical use, FDA will require an applicant to provide data demonstrating that 1) the excipient is safe in the amount it will be used or consumed in the finished drug throughout the product’s recommended or prescribed duration of use by those who will take the product. In addition, the applicant must 2) demonstrate that the substance meets applicable compendial standards where they apply; 3) that it performs its intended function in the product; that it 4) does not adversely affect the bioavailability and performance of the active drug; and 5) is manufactured in accordance with appropriate standards of good manufacturing practice suitable to that kind of excipient. Still, as noted earlier, there is no FDA regulatory approval system that is exclusively applicable to pharmaceutical excipients. Thus, the scope and amount of necessary data to support a substance or its use always must be negotiated with FDA and will be determined on a case by case basis.