Although garden-variety metformin hasn’t really changed in 50 years, several new formulations have been introduced since that time. For people who have a hard time swallowing pills, metformin comes in a liquid formulation called Riomet. The most popular variant, however, is an extended-release version of the drug. Metformin is only absorbed within the body at the very upper part of the gastrointestinal tract, and any portion of the drug that passes further “downstream” is simply excreted. The trick to extending the action of the drug, then, is to keep the pill in the stomach longer while releasing the medicine slowly.
The most commonly prescribed extended-release version of metformin is Glucophage XR. This pill accomplishes its mission with a polymer that turns into a gel in the stomach, which blocks quick absorption of the medicine. This XR formulation has been shown to prolong the absorption of the drug to a peak of around seven hours, compared with traditional metformin’s three-hour peak in working action.
Indian researchers have also experimented with a floating pill that would stay in the stomach for even longer, slowly releasing metformin the entire time. For as long as metformin remains a popular diabetes drug, it is a safe bet that researchers will be trying to create new and innovative ways to deliver it to the body.
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