“Purple Book” is different to “Orange Book,” the orange book is named for the FDA publication (Approved Drug Products with Therapeutic Equivalence Evaluations) that contains therapeutic equivalence evaluations for approved multisource prescription drug products. The original print version had a distinctive orange cover.

Purple Book

The Purple book is a database, that contains information of biological products, including biosimilar and interchangeable biological products, licensed (approved) by the FDA under the Public Health Service (PHS) Act.
The FDA introduced the Purple Book in list format in September 2014. These lists are designed to provide information about biological products licensed by the Food and Drug Administration (FDA), including biological products that the FDA has determined to be biosimilar or interchangeable with a reference biological product.
The lists cross-reference the names of biological products licensed under section 351(a) of the Public Health Service (PHS) Act with the names of biosimilar or interchangeable biological products licensed under section 351(k) of the PHS Act by the FDA.

The Purple Book lists include the following information about biological products:

• The date on which the product was licensed under section 351(a) of the PHS Act.
• Whether FDA evaluated the product for reference product exclusivity.
• Whether the product has been determined to be biosimilar or interchangeable with a reference product (i.e., a previously licensed biological product).
• To facilitate use of Purple Book information, biosimilar products and interchangeable products are grouped under the reference product to which biosimilarity or interchangeability was demonstrated.

There are separate lists for those biological products regulated by the Center for Drug Evaluation and Research (CDER) and the Center for Biologics Evaluation and Research (CBER). These are updated periodically.
The current Purple Book lists are available on the FDA website.
The FDA is working to expand the Purple Book by transitioning the current list format into a searchable database that is accessible online. This improved Purple Book will be released in multiple phases. The first phase was released on 24th Feb, 2020, that contains information on licensed biosimilar and interchangeable products, as well as their reference products. Future releases will expand the number of FDA-licensed biological products until the Purple Book online database includes information about all FDA-licensed biological products.
The Purple Book lists will continue to be updated periodically until all functionality and all BLAs are available on the new Purple Book online database.
Once the Purple Book database is completed, it will provide information about all licensed biological products, including exclusivity. Then after Purple Book list will no longer be updated or available.
The first phase of purple book online database available on FDA website. The database home page looks like the image below.
Purple book link: https://purplebooksearch.fda.gov/
Currently, the “Purple Book” is available in two versions,

1. Lists format

1. Online searchable database.

The lists contain information about all FDA-licensed biological products. The new, searchable database contains information about a limited number of FDA-licensed biological products: licensed biosimilar and interchangeable products, and their reference products.
Biosimilar and interchangeable biological products licensed under section 351(k) of the PHS Act will be listed under the reference product to which biosimilarity or interchangeability was demonstrated.

What is a reference product?

A reference product is the single biological product licensed by the FDA under section 351(a) of the PHS Act against which a proposed biological product is evaluated in an application submitted under section 351(k).

What is a biosimilar product?

Biosimilar or Biosimilarity means that the biological product is highly similar to the reference product notwithstanding minor differences in clinically inactive components, and there are no clinically meaningful differences between the biological product and the reference product in terms of the safety, purity and potency of the product.

What is an interchangeable product?

An interchangeable biological product is a product that has been shown to be biosimilar to the reference product and can be expected to produce the same clinical result as the reference product in any given patient.

In addition, for a biological product that is administered more than once to an individual to be determined to be interchangeable, it must be shown that the risk in terms of safety or diminished efficacy of alternating or switching between use of the biological product and the reference product is not greater than the risk of using the reference product without such alternation or switch.
This new database of the Purple Book will make more information about FDA-licensed biological products more accessible, increasing transparency for patients, industry users and other stakeholders.
It will meet the needs of a wide range of users, from providing a simple search for patients and consumers, to a more advanced search for prescribers, researchers and industry representatives that may have a need for more technical information.
Providing stakeholders with more information about biological products through a modernized platform should better facilitate the acceptance and use of existing biosimilar products and the development of new ones, potentially leading to lower costs for patients and improved access to safe, effective, high-quality medications.