FDA-2025-E-0707 for “Determination of Regulatory Review Period for Purposes of Patent Extension; DAYVIGO.” Under these acts, a product's regulatory review period forms the basis for determining the amount of extension an applicant may receive. Determination of Regulatory Review PeriodFDA has determined that the applicable regulatory review period for DAYVIGO is 3,004 days. This determination of the regulatory review period establishes the maximum potential length of a patent extension. In its application for patent extension, this applicant seeks 930 days of patent term extension.