Metformin ER – Can I Substitute?
Many pharmacies struggle with identifying which metformin ER product they can dispense or substitute. There are three different strengths and three different extended-release mechanisms. The FDA uses Therapeutic Equivalency (TE) codes to show which generic products can be substituted for a specific brand name. When there are multiple branded versions of an identical active drug ingredient, form, and route of administration, then the FDA must assign each brand an additional identifier such as AB, AB1, AB2 and AB3. The brand names below are different due to their extended-release mechanisms. Generic versions may only be substituted for the brand with the same TE code.
Brand Name | Strengths (mg) | FDA Orange Book
TE Codes |
Extended-Release Format |
Glucophage XR® | 500, 750 | AB, AB1 | Dual hydrophilic polymer system |
Fortamet® | 500, 1000 | AB2 | Single-Composition Osmotic Technology (SCOT) |
Glumetza® | 500, 1000 | AB3 | Gastric Retention Technology |
For example, if you receive a prescription for Fortamet® 1000 mg, you may dispense with the brand name product or a generic formulation with a TE code of AB2
PAAS Tips:
the patient has been on or which “version” the prescriber prefers and notate on the prescription
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