Author byline as per print journal: Joseph P Park1, PhD; Gillian R Woollett2, MA, DPhil

Abstract:
US Food and Drug Administration’s (FDA) current thinking on interchangeability has evolved since the legal designation was first created in 2010. Based on experience, FDA now acknowledges that clinical switching studies are not generally needed for the interchangeability designation as quality, safety and efficacy are established by biosimilarity already.

Approval pathways for biosimilars and interchangeable biosimilars were first introduced in the US through enactment of Biologics Price Competition and Innovation Act of 2009 (BPCI Act) (itself Title VII part of the Patient Protection and Affordable Care Act) on 23 March 2010 [1]. The interchangeability designation, unique to the US, enables pharmacists (subject to state law) to substitute the US Food and Drug Administration (FDA)-designated biosimilars for the reference product without involving the original healthcare providers (HCPs) (albeit they will be notified subsequently). As such, an interchangeability designation is about dispensing, not prescribing. The basis upon which the FDA designation is given has been a subject of much debate, and on 21 June 2024, FDA issued a Draft Guidance ‘Considerations in Demonstrating Interchangeability With a Reference Product: Update [2]’ clarifying that biosimilar sponsors may apply for the designation at any time without the previously generally required additional clinical switching studies.

Submitted: 16 July 2024; Revised: 6 August 2024; Accepted: 8 August 2024; Published online first: 21 August 2024

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This manuscript has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.