Metformin Extended-Release Oral Solution

Metformin hydrochloride extended-release oral suspension (Riomet ER) is a reformulation of a biguanide that was approved by the U.S. Food and Drug Administration on 29 August 2019 for the treatment of type 2 diabetes (1). The American Diabetes Association’s Standards of Medical Care in Diabetes—2021 recommends metformin as the preferred initial pharmacological agent for treatment of type 2 diabetes (2). These guidelines also recommend that, once initiated, metformin should be continued as tolerated. Before the approval of Riomet ER, metformin was available as immediate-release tablets, extended-release tablets, and an immediate-release oral solution. Metformin is the only biguanide agent currently available in the United States. According to GoodRx, it was the eighth most commonly prescribed medication in the United States as of August 2020 (3). Riomet ER is indicated to be used in combination with diet and exercise to improve glycemic control in both adults and children ≥10 years of age with type 2 diabetes (4). Riomet ER is available as 47.31 g metformin hydrochloride for reconstitution in a 473-mL bottle. Upon reconstitution, the final concentration is 500 mg/5 mL. The recommended starting dose is 5 mL (500 mg) orally once daily with the evening meal. The dose can be increased in 5-mL increments weekly up to a maximum dose of 20 mL (2,000 mg) once …