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Preventing Substitution Errors Among Interchangeable Denosumab Biosimilars
- By: Margaret Ridley
- On: 03/06/2026 12:36:09
- In: KPhA Updates
Preventing Substitution Errors Among Interchangeable Denosumab Biosimilars
Many pharmacies are familiar with Prolia® (denosumab) for the treatment of osteoporosis in women after menopause who are high risk for fracture or cannot use another osteoporosis medication (or the other medications weren't efficacious). There is another denosumab product (brand name Xgeva®) approved for bone problems due to cancer. Prolia® and Xgeva® are not interchangeable because their strengths and dosing schedules differ.
In 2025, there were at least 14 denosumab interchangeable biosimilars approved for Prolia® and Xgeva® alone. The question with the multiple approved products is how to determine which ones can be used for each of the reference products. The FDA Purple Book is the go-to reference for differentiating between biosimilars and helping with substitution.
One example is denosumab-bbdz (proprietary names: Jubbonti®, Wyost®). Jubbonti® is only interchangeable to Prolia® and Wyost® to Xgeva®. These substitutions can be made without authorization from the prescriber (if your state law allows). When ordering a denosumab product from wholesalers, you will want to make sure that the one you order is interchangeable to the originally prescribed product.
PAAS Tips:
Many pharmacies are familiar with Prolia® (denosumab) for the treatment of osteoporosis in women after menopause who are high risk for fracture or cannot use another osteoporosis medication (or the other medications weren't efficacious). There is another denosumab product (brand name Xgeva®) approved for bone problems due to cancer. Prolia® and Xgeva® are not interchangeable because their strengths and dosing schedules differ.
In 2025, there were at least 14 denosumab interchangeable biosimilars approved for Prolia® and Xgeva® alone. The question with the multiple approved products is how to determine which ones can be used for each of the reference products. The FDA Purple Book is the go-to reference for differentiating between biosimilars and helping with substitution.
One example is denosumab-bbdz (proprietary names: Jubbonti®, Wyost®). Jubbonti® is only interchangeable to Prolia® and Wyost® to Xgeva®. These substitutions can be made without authorization from the prescriber (if your state law allows). When ordering a denosumab product from wholesalers, you will want to make sure that the one you order is interchangeable to the originally prescribed product.
PAAS Tips:
- If you are in doubt as to whether products may be substituted
- Call the prescriber to obtain approval and document with a full clinical note
- Contact a PAAS National® expert for assistance
By Trenton Thiede, PharmD, MBA, President at PAAS National®, expert third party audit assistance, FWA/HIPAA and USP 800 compliance.
Copyright © 2026 PAAS National, LLC. Unauthorized use or distribution prohibited. All use subject to terms at https://paasnational.com/terms-of-use/.
What does this mean for Kentucky:
A Kentucky pharmacist cannot substitute a biologic unless they also follow Kentucky's specific regulatory steps. These regulatory steps include:
- The biosimilar must be FDA-designated interchangeable with the specific reference biologic (not just “biosimilar”). To identify which products are interchangeable, use the FDA Purple Book.
- The substituted product must be lower in price than the prescribed product.
- The pharmacist must notify the prescriber of which product was dispensed (name and manufacturer) within five business days.
- The pharmacist must label the dispensed product appropriately.
Written by Allison Grant, APPE Student Intern, KPhA.