A Boxed Warning regarding lactic acidosis has been added to the label for Metformin Hydrochloride ER, effective 2026-06-09. This significant label revision highlights the potential for serious adverse outcomes, including death, hypothermia, hypotension, and resistant bradyarrhythmias, associated with metformin use. The onset of metformin-associated lactic acidosis is often subtle.
Background
Metformin Hydrochloride ER is an extended-release formulation of metformin, a widely prescribed oral antihyperglycemic agent. It is primarily used in the management of type 2 diabetes mellitus to improve glycemic control. Metformin belongs to the biguanide class of drugs and works by decreasing hepatic glucose production, decreasing intestinal absorption of glucose, and improving insulin sensitivity by increasing peripheral glucose uptake and utilization. Lactic acidosis is a rare but serious metabolic complication that can occur due to metformin accumulation, particularly in patients with impaired renal function or other predisposing conditions. The Boxed Warning emphasizes the severity of this risk, which has been identified through postmarketing cases of metformin-associated lactic acidosis.
What this means
The addition of a Boxed Warning to the Metformin Hydrochloride ER label serves as a critical update for healthcare providers and patients. It underscores the importance of vigilance for the signs and symptoms of lactic acidosis, which include death, hypothermia, hypotension, and resistant bradyarrhythmias. Clinicians should carefully assess patient risk factors, such as renal impairment, concomitant use of certain drugs, and conditions that can lead to hypoperfusion or hypoxemia, before initiating or continuing metformin therapy. Patient education regarding the symptoms of lactic acidosis and the need for immediate medical attention is also paramount. This label change reinforces the need for careful patient selection and monitoring to mitigate this severe, potentially fatal, adverse event.
Source
The information regarding this label revision was obtained from the FDA, as documented on DailyMed. This update, effective 2026-06-09, can be verified through the official record on dailymed.nlm.nih.gov.