Metformin dosage, side effects

Metformin dosage, side effects:

Metformin is a widely prescribed oral medication primarily used to manage type 2 diabetes. It belongs to the biguanide class of drugs and works by improving insulin sensitivity, reducing glucose production in the liver, and enhancing glucose uptake by muscles. It is often the first-line treatment for type 2 diabetes, especially in overweight or obese patients.

Mechanism of Action

Reduces hepatic glucose production: Metformin inhibits gluconeogenesis (the process of glucose production in the liver).
Improves insulin sensitivity: It enhances the body’s response to insulin, particularly in muscle tissues.
Decreases intestinal glucose absorption: It modestly reduces glucose absorption from the intestines.
Increases GLP-1 levels: Metformin may increase levels of glucagon-like peptide-1 (GLP-1), a hormone that promotes insulin secretion.

Indications

Type 2 Diabetes Mellitus: As monotherapy or in combination with other antidiabetic medications.
Polycystic Ovary Syndrome (PCOS): Off-label use to improve insulin resistance and regulate menstrual cycles.
Prediabetes: Sometimes used to prevent progression to diabetes.
Weight Management: May aid in modest weight loss in some patients.

Brand Names

Metformin is sold under various brand names worldwide. Some of the most common include:

United States:

Glucophage (immediate-release)
Glucophage XR (extended-release)
Fortamet (extended-release)
Glumetza (extended-release)
Riomet (liquid formulation)

International Brand Names:

Glycoran (India)
Metforal (France)
Siofor (Europe)
Dianben (Spain)
Diabex (Australia)
Metfogamma (Germany)
Cidophage (Middle East)

Dosage Forms

Immediate-Release (IR) Tablets: Typically taken 2-3 times daily.
Extended-Release (ER or XR) Tablets: Taken once daily, usually with the evening meal.
Oral Solution: Available as Riomet for patients who have difficulty swallowing tablets.

Dosage

Initial Dose: Usually 500 mg once or twice daily, or 850 mg once daily.
Maintenance Dose: Can be increased gradually to a maximum of 2000-2550 mg per day, depending on the formulation.
Extended-Release: Max dose is typically 2000 mg once daily.

Side Effects

Common side effects are usually gastrointestinal and may include:

Nausea
Diarrhea
Abdominal discomfort
Bloating
Metallic taste in the mouth

Rare but serious side effects:

Lactic acidosis: A rare but potentially life-threatening condition, especially in patients with kidney or liver impairment.
Vitamin B12 deficiency (with long-term use).

Contraindications

Severe kidney impairment (e.g., eGFR < 30 mL/min).
Metabolic acidosis or history of lactic acidosis.
Severe liver disease.
Hypersensitivity to metformin.

Drug Interactions

Alcohol: Increases the risk of lactic acidosis.
Iodinated contrast dye: Temporarily discontinue metformin before and after procedures involving contrast dye.
Cimetidine: May increase metformin levels.
Thiazide diuretics: May reduce glucose control.

Special Populations

Elderly: Use with caution due to increased risk of kidney impairment.
Pregnancy: Generally considered safe (Category B) but consult a doctor.
Breastfeeding: Metformin passes into breast milk but is considered compatible with breastfeeding.

Advantages

Effective in lowering blood glucose without causing hypoglycemia (when used alone).
May promote modest weight loss or weight neutrality.
Low cost and widely available.

Disadvantages

Gastrointestinal side effects can be bothersome for some patients.
Requires dose adjustment or discontinuation in kidney impairment.
Rare risk of lactic acidosis.

Conclusion

Metformin remains a cornerstone in the management of type 2 diabetes due to its efficacy, safety profile, and low cost. It is also used off-label for conditions like PCOS. However, it is essential to monitor kidney function and educate patients about the signs of lactic acidosis. Always consult a healthcare provider for personalized medical advice.