Practitioner Updates

Pharmacist’s Corner: Semglee vs. Lantus:  What’s the Difference?

It is impossible to chemically synthesize an exact and identical copy of a biological.

In July 2021, the FDA approved Semglee (insulin glargine-yfgn), the first interchangeable biosimilar insulin product for Lantus (insulin glargine).1 Insulin glargine is a basal long-acting human insulin analog used to manage patients with type I and type II diabetes. Semglee is available as a 100 unit/ mL solution, as a 3 mL pen and a 10 mL vial, exactly like Lantus.2

Is a biosimilar the same as a generic?

A “generic” is a non-biologic product that undergoes approval with the FDA to establish that the generic drug has the same active ingredients, route of administration, dosage form, and strength and have the same rate and extent of bioavailability at the site of action as the original product. It can have different coloring, shape, excipients, and binders from the original manufactured product.

A “biosimilar” is a biologic product derived from living organisms or cells that is approved based on its ability to show no clinically meaningful differences in terms of safety and efficacy between an already FDA-approved reference product. Due to the complexity and size of biologicals, it is impossible to chemically synthesize an exact and identical copy, as in generic medications. Biosimilars go through a separate FDA approval process. Neither biosimilars nor generics can enter the market before the brand drug patent expires.3

What about other insulin glargine products?

Basaglar, another insulin glargine product, was produced before the creation of the biosimilar comparison process with a reference product. Since Lantus was not studied as the reference product, Basaglar and Lantus cannot be exchanged without authorization from the prescriber.4 Since Semglee is an interchangeable biosimilar to Lantus, it is not interchangeable with Basaglar. In December 2021, the FDA approved a new biosimilar for Lantus called Rezvoglar (insulin glargineaglr), but it currently does not have interchangeable status and requires a prescription written specifically for the product.5 Toujeo, insulin glargine available in 300 units/mL, remains under investigation for use in veterinary patients.6

What is the cost difference between Lantus and Semglee?

The average wholesale price for a 5-pack of insulin pens is $177.58 for Semglee and $510.31 for Lantus. The average wholesale price for a 10-mL vial is $118.38 for Semglee and $340.27 for Lantus. These prices can further be reduced using discount cards or possibly ordering through a veterinary drug distributor.7

Is Semglee safe for veterinary use?

Semglee contains the same active ingredients that are found in Lantus and is expected to have the same side effects and efficacy.6 However, no studies are currently completed confirming the expected outcome in veterinary patients. Veterinarians should use clinical judgment on an individual patient basis to determine whether Semglee would be an appropriate choice for their patients.


1. FDA approves first interchangeable biosimilar insulin product for treatment of diabetes [Internet]. U.S. Food and Drug Administration. FDA; 2021 [cited 2022Mar15]. Available from:

2. Semglee [package insert]. Morgantown, WV: Mylan Pharmaceuticals; 2021.

3. What are biosimilars and Biologics? [Internet]. Pfizer Biosimilars. 2021 [cited 2022Mar15]. Available from:

4. Newsome C. Basaglar [Internet]. American Diabetes Association; 2017 [cited 2022Mar15]. Available from:

5. FDA approves second biosimilar insulin product, Rezvoglar (insulin glargine-AGLR) [Internet]. PracticeUpdate. 2021 [cited 2022Mar15]. Available from:

6. Plumb DC. Insulin glargine. Plumb’s Veterinary Drugs. May 2020. [cited 2022 Mar 11]. Available from:

7. RED BOOK. IBM Micromedex [database online]. Truven Health Analytics/IBM Watson Health; 2022 [cited 2022Mar15].

Maria Faber, recently a pharmacy intern in our hospital, earned her PharmD from the University of Findlay, Findlay, Ohio, last month.