Can You Cut Or Split Metformin ER In Half?

Many medications have some type of "modified-release mechanism". These include formulations such as 'extended-release' and 'delayed-release'. In general, these medications should not be crushed or cut as this can compromise the release mechanism. Having said that, there are some examples of medications that are OK to split, even though they have a modified release mechanism. In this article, we answer whether or not it is OK to cut Metformin ER tablets.

Oct 03, 2017

Beatrice asked

Can I Cut My Metformin ER Tablet In Half? They Are Very Large & I Am Having Trouble Swallowing Them?


There are 3 different Metformin ER products available:

  • ​Glucophage XR
  • Glumetza ER 
  • Fortamet ER

All 3 formulations are available generically but they are not interchangeable as they all use different release mechanisms.

Glucophage XR uses a dual hydrophilic polymer system. The drug is slowly released by diffusing through a gel matrix, also known as GelShield diffusion system. Once the tablet is swallowed, the outer layer of the tablet forms a gel layer and the metformin contained within is slowly released. Due to this release mechanism, Glucophage XR can not be cut or split.​​​​

Glumetza ER uses a mechanism known as gastro-retentive technology (also known as 'Modified Release'). The tablets are designed to remain in the stomach and deliver metformin to the upper GI tract over an extended period of time. Like Glucophage XR, Glumetza ER can not be cut or split. 

​Fortamet ER uses single-composition osmotic technology (SCOT). After taking a tablet by mouth, water is taken up through the tablet membrane, which dissolves the drug in the core. The drug then slowly exits through a small hole in the tablet. Medications that use this technology are typically visible in the stool as the actual tablet does not dissolve. Like the other metformin products, ​Fortamet ER can not be cut or split.​

After reviewing all of the different extended release formulations, we can see that unfortunately there are no metformin ER products that can be cut or split. If you cannot swallow the tablets, consider the immediate release or liquid formulation.

Splitting, cutting or the crushing of tablets (or ER capsules) with a controlled release mechanism, can cause what is known as “dose dumping,”. This can lead to a overdose and toxic effects of the drug. For this reason, Metformin ER formulations should not be altered.​​

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