As Prescribed


The Purple Book—a database containing information about all licensed biological products—is set for a revamping that offers more patent transparency regarding reference biologics.

The Purple Book, which was first published in 2014, a year before the 2015 approval of the first biosimilar product, lists FDA-licensed biological products (including biosimilars) and currently provides information on the biologic’s name, application number, approval date, date of first licensure, and biosimilar information. However, because the Purple Book is less established than its small molecule older sibling (the Orange Book), not all the foregoing information is regularly populated for every biologic product (e.g., first licensure date is frequently omitted). Additionally, it was only in February 2020 that the Purple Book transitioned from two separate tables (one for the Center for Drug Evaluation and Research and one for the Center for Biologics Evaluation and Research) to a single searchable database.

Despite the progress made with respect to the Purple Book, the one item included in the Orange Book that is missing from the Purple Book is patent information. This, however, will be changing next month (assuming FDA meets statutory timelines). Under the Purple Book Continuity Act (PBCA), enacted in December 2020 as part of the Consolidated Appropriations Act, the Purple Book will include the following additional data elements:

  • Exclusivity Information – The Purple Book must identify unexpired reference product and interchangeable product exclusivity periods where FDA has made an eligibility decision. Notably, however, under the text of the statute, the listed exclusivity periods would only include the 12-year reference product exclusivity and exclusivity granted to interchangeable biosimilar products. To determine whether a product is subject to periods of orphan drug exclusivity, companies will still need to refer to FDA’s orphan drug database. It is also unclear whether six-month pediatric exclusivity extensions will be added onto the Purple Book exclusivity periods. Moreover, the statute only requires that exclusivities be posted if FDA has made an exclusivity eligibility determination. At least with respect to small molecules, FDA frequently does not make official exclusivity determinations until the issue becomes ripe (e.g., through the filing of an abbreviated new drug application or 505(b)(2) New Drug Application). If the Purple Book follows in the Orange Book’s steps, exclusivity periods will not necessarily be included for every newly licensed biologic as FDA may not have made an official exclusivity determination in every case.
  • Patent Information – Within 30 days of disclosing a patent list to a biosimilar product applicant, the reference product sponsor must submit the list to FDA for inclusion in the Purple Book. Interestingly, however, the statute leaves open the question of what happens if the biosimilar sponsor decides not to engage in the patent dance. Moreover, unlike the Orange Book, the Purple Book’s patent posting requirements would not be triggered until there is a first biosimilar product applicant. Accordingly, until a biosimilar filing, patent information would not be posted in the FDA database. Finally, and also unlike the Orange Book, there is no obligation for product sponsors to keep patent information in the Purple Book current. Accordingly, subsequent applicants should not solely rely on the Purple Book when trying to understand potential patent challenges under FDA’s statutes.

For analysis of the Purple Book’s new data elements from a patent perspective, and particularly from the perspective of small- and medium-sized enterprises, please see this April 26 Law Flash, authored by our colleagues.