An FDA approval is required before a new animal drug can be introduced into interstate commerce. The FDA approval occurs in two phases: a testing phase, followed by an approval phase. If there is a patent on the new animal drug, the patent owner may request for extension of the patent term to restore the patent life lost during the duration of the FDA review. The extension that may be obtained is half of the duration of the test phase plus the entire duration of the approval phase. The extension cannot exceed five years and cannot include any regulatory review period occurring before the patent issues.
The testing phase begins when a drug sponsor obtains FDA’s permission to begin clinical testing of the drug or initiates a major health or environmental effects test. During the testing phase, the sponsor submits investigational data to the FDA, and this data is stored in an Investigational New Animal Drug (INAD) file. In the traditional regulatory review process, the testing phase ends, and the approval phase begins, when the sponsor submits a New Animal Drug Application (NADA) to the FDA. The NADA contains all the information required by 21 USC 360b(b) in a single submission.
The FDA now offers sponsors a phased review as an alternative to the traditional review. The phased review is a streamlined process in which the information required by 21 USC 360b(b) can be submitted to the FDA in a piecemeal fashion as technical sections. The FDA reviews each technical section as it receives the technical section and sends the sponsor a complete letter when the review is completed. Once the sponsor has a complete set of complete letters, the sponsor can file an administrative NADA.
In Wyeth Holdings, Corp. v. Sec. of Health and Human Services (Federal Circuit 2009-1368, decided 3 May 2010), a question arose as to how to determine the onset date for the approval phase, for the purpose of calculating patent term extension, when the sponsor uses the phased review. The FDA had weighed in on the matter and informed the U.S. Patent and Trademark Office that the onset date for the approval phase is the date on which an administrative NADA is submitted. Wyeth wanted the FDA to set the onset date for the approval phase as the date the first technical section is submitted, but the FDA declined to do so. The District Court judged in favor of the FDA’s interpretation of when the approval phase begins for phased review, and the Federal Circuit affirmed the decision of the district court.