Prescription Dispensing for Insulin Glargine After Interchangeable Biosimilar Designation

Area of Science:

• Health Economics and Outcomes Research
• Pharmaceutical Policy
• Pharmacoeconomics

Background:

• The US Food and Drug Administration (FDA) approved the first interchangeable biosimilar, insulin glargine (Semglee), in 2021, allowing pharmacy substitution.
• The impact of this interchangeable designation on prescription dispensing patterns remained largely unknown prior to this study.

Purpose of the Study:

• To evaluate the effect of Semglee's transition to interchangeable designation on its prescription dispensing.
• To assess the role of interchangeability in the utilization of biosimilar medications.

Main Methods:

• An economic evaluation analyzed insulin glargine dispensing data from September 2019 to June 2024.
• Data sources included IQVIA's National Prescription Audit and PayerTrak for US pharmacy dispensing.
• Dispensing changes were assessed before and after the November 2021 interchangeable designation, controlling for formulary changes.

Main Results:

• A significant increase in aggregate Semglee/insulin glargine-yfgn dispensing (47.41%) was observed post-interchangeable designation (P=.001).
• Dispensing increased across retail, mail, and long-term care channels, indicating broad utilization growth.
• Insulin glargine-yfgn adoption outpaced Semglee in Medicare Part D, Medicaid, and cash channels after launch.

Conclusions:

• The first FDA interchangeable designation for insulin glargine was associated with a substantial increase in its dispensing.
• Interchangeability appears to be a key factor in driving biosimilar utilization and market share.
• This designation holds promise for reducing healthcare costs and improving patient access to biosimilar prescription drugs.