Metformin

Original Editor - Ashton Randolph

Top Contributors - Lucinda hampton, Ashton Randolph and Aminat Abolade  

Introduction

Metformin, FDA-approved in 1994, is an antidiabetic agent used in type 2 diabetes mellitus. Metformin comes in both immediate-release and extended-release and is available in several combination products with other antidiabetic agents.[1]

Typically at diagnosis of type 2 diabetes, lifestyle management such as diet and exercise are recommended. Metformin is often used as monotherapy or in combination when diet and exercise are not effective at lowering hyperglycemia. According to the American Diabetes Association (ADA), metformin is the preferred first-line agent in patients with type-2 diabetes mellitus in adults and children ten years and older.

Administration

Metformin is an oral medication typically dosed from 500 to 2550 mg per day and administered with a meal to decrease GI upset. The daily dose is often titrated weekly in increments of 500 mg or 850 mg to reduce this risk.

• Recommendations are to take metformin at the same time every day.
• Extended-release tablets are typically taken once daily with an evening meal and should be swallowed with a full glass of water.

Adverse Effects

Metformin is generally regarded as safe and well-tolerated.

• Gastrointestinal side effects, including diarrhea, nausea, and vomiting, are very common and typically occur in up to 30% of patients taking metformin.
• Occurring less frequently, some patients experience chest discomfort, headache, diaphoresis, hypoglycemia, weakness, and rhinitis.
• Decreased vitamin B12 levels are associated with long-term metformin and should be monitored, particularly in anemic or peripheral neuropathy patients. Supplementation of vitamin B12 may be necessary

While being one of the safest options in the biguanide class, metformin consumers may still experience serious side effects.

• Lactic acidosis, a rare but dangerous side-effect experienced, may present with confusion, lethargy, stupor, shallow breathing, hypotension, nausea and vomiting.
• Hypoglycemia may display as anxiety, restlessness, paresthesia, cold sweat, confusion, headache, instability, and irritability

Those taking metformin should be wary of the consumption of certain items which may increase metformin’s side effect profile. Substances that should be cautioned include:

• Alcohol, which increases the risk of lactic acidosis
• The use of amiloride, digoxin, and morphine, because of their competition for elimination pathways
• Cimetidine and furosemide which increase metformin’s effect.

Education

Education is also is extremely important when working with a patient taking metformin. Therapists must educate the patient on their role in monitoring their glucose levels. They should be reminded to eat before therapy or physical activity, to avoid hypoglycemia. They must monitor for changes and signs and symptoms of hyperglycemia, hypoglycemia, lactic acidosis, vitamin B deficiencies, and gastrointestinal discomfort. Patients must also be counseled on proper administration, and storage of metformin at room temperature, avoiding extreme temperatures and light. Abnormalities, or apprehensions must be reported and discussed with primary healthcare provider so dosage can be modified or patient switched to a different medication.

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