The NDA contains data from animal and human studies; it is illegal to exclude any pertinent data. It also has information on product manufacturing and characteristics, packaging and labeling for both physician and consumer, IND data, and the results of any additional toxicologic studies that were not included in the IND (21 CFR 314.50) (CDER et al., 1998). Data on the use of the drug outside the United States may be included in the NDA. In the early 1980s, only about 2 or 3 percent of new drugs were first marketed in the United States, so useful safety data on use abroad could sometimes be included (Friedman et al., 1999). By 1998, that proportion grew to 50 percent and the proportion of drugs launched in the United States first has increased with each reauthorization of PDUFA: I, 25.23 percent; II, 47.19 percent; and III, 50 percent (FDA, 2005d; Okie, 2005).
Unlike their European counterparts who generally rely on the sponsor’s summaries, FDA reviewers compile and reanalyze the data submitted by the sponsor and use the analyses, as well as the one done by the sponsor, to inform their decision about the drug.
Throughout the review process, the sponsor may be submitting amendments in response to FDA requests or to complete work identified in the pre-NDA meeting. If major amendments arrive in the last 3 months of the review, the PDUFA clock may be extended (FDA, 2002). As issues arise, the sponsor or FDA may request formal meetings during the process to resolve disputes or discuss pending concerns. The number of such meetings varies, but it is not uncommon for several meetings to be held while the application is under review.
PDUFA establishes specific timelines for FDA to respond to an industry request for a meeting, schedule the meeting, and distribute minutes from it (FDA, 2005g). The PDUFA goals were associated with about a 33 percent increase in sponsor-requested meetings from fiscal year (FY) 1999 to FY 2004 (FDA, 2005d). That has required FDA staff to devote many hours to planning, conducting, and following up on the meetings. Although time-consuming and resource-intensive, the meetings can clarify issues and improve the review process by reducing the risk of misunderstandings late in the review process.
During the review process, a decision may be made, usually by the division director, to convene an advisory committee meeting (see Box 2-3 for deadlines to convene an advisory committee meeting). Advisory committees are used as a source of independent advice from experts outside FDA (FDA, 2006b). Chapter 4 discusses advisory committees in more detail.