Diabeta vs Micronase: What’s the Difference?

Roni Shye
Roni Shye, PharmD BCGP BCACP, is a licensed pharmacist in the states of Florida, Ohio, and Pennsylvania.
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As you may already know, there are two different forms of glyburide, regular nonmicronized glyburide (Micronase, Diabeta) and micronized glyburide (Glynase) that can’t be substituted for each other. So, what about Diabeta and Micronase? Both have glyburide as an active ingredient, both are used type 2 diabetes to improve glycemic control and lower blood sugar levels, and they come in the same dosages—however, they also can’t be substituted for each other.

Is Diabeta therapeutically equivalent to Micronase?

No. As a matter of fact, although they may share glyburide as an active ingredient, Diabeta is not equivalent to any other medication available. It is BX rated by the FDA to all other glyburide products.

What does a BX rating mean?

Per the FDA:

The code BX is assigned to specific drug products for which the data that have been reviewed by the Agency are insufficient to determine therapeutic equivalence . . . In these situations, the drug products are presumed to be therapeutically inequivalent until the Agency has determined that there is adequate information to make a full evaluation of therapeutic equivalence.

Often the problem is with specific dosage forms rather than with the active ingredients.

So, there may not be specific evidence that Diabeta is not equivalent to other glyburide medications, but there isn’t enough evidence to prove that it is equivalent. It may be that the dosages or forms of Diabeta are not similar enough, rather than a difference in the active ingredient.

Can generic glyburide be substituted for Diabeta?

No. Diabeta does not have a generic glyburide counterpart. If your doctor writes a prescription for Diabeta, it MUST be dispensed as Diabeta.

Can a generic glyburide be substituted for Micronase?

Yes. Generic glyburide can be substituted for Micronase; they are equivalent. The exception would be micronized glyburide, which is equivalent to Glynase instead.

Can Diabeta and Micronase be substituted for one another?

No. Here’s where it gets a little complicated. Even though the generic for both Diabeta and Micronase is glyburide, they have not been deemed therapeutically equivalent by the FDA. Diabeta, Micronase, and generic glyburide also cannot be substituted for Glynase or micronized glyburide.

FYI:

I attempted to contact the company that makes Diabeta, Sanofi-Aventis, regarding the exact reason why the medication is not rated as equivalent to other glyburide products. However, they could not give me the exact reason. They said it is an older drug from 1984 that they inherited from another pharmaceutical company, Hoechst.

Check out this article for more insight into this glyburide debacle.

As it stands no one can really explain the exact reason of its therapeutic inequivalence to the generics just that Diabeta CANNOT be substituted.

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