Detailed Guide with FAQs
Introduction
- Metformin is a first-line oral medication for managing Type 2 Diabetes Mellitus (T2DM).
- Belongs to the biguanide class, primarily improving insulin sensitivity and reducing glucose production.
- Known for its efficacy, safety, and additional benefits like weight stabilization and cardiovascular protection.
Class and Mechanism of Action
- Drug Class: Biguanides.
- Mechanism:
- Reduces hepatic glucose production (gluconeogenesis).
- Increases peripheral insulin sensitivity, enhancing glucose uptake by muscles.
- Decreases intestinal absorption of glucose.
Indications
- Type 2 Diabetes Mellitus (T2DM): First-line therapy for glycemic control.
- Polycystic Ovary Syndrome (PCOS): Off-label use to regulate menstrual cycles and improve insulin resistance.
- Prediabetes: Reduces progression to Type 2 Diabetes in high-risk individuals.
Dosage and Administration
- Formulations: Oral tablets (immediate-release and extended-release) and liquid solution.
Typical Dosage
- Immediate-Release Tablets:
- Initial dose: 500 mg once or twice daily with meals.
- Maintenance dose: 1,500–2,000 mg/day divided into 2–3 doses.
- Maximum dose: 2,550 mg/day.
- Extended-Release Tablets:
- Initial dose: 500 mg once daily with evening meal.
- Maximum dose: 2,000 mg/day.
Administration Guidelines
- Take with food to reduce gastrointestinal side effects.
- Swallow extended-release tablets whole; do not crush or chew.
Forms, Brand Names, Manufacturers, and Prices
- Brand Names: Glucophage (Merck), Glumetza, Fortamet.
- Price: ~$10–$30 per pack (generic versions available and significantly cheaper).
- Availability: Widely accessible globally in both branded and generic forms.
Contraindications and Precautions
- Contraindications:
- Severe kidney impairment (eGFR <30 mL/min/1.73 m²).
- Metabolic acidosis or diabetic ketoacidosis (DKA).
- Acute or chronic conditions that may cause hypoxia (e.g., heart failure, severe respiratory disease).
- Precautions:
- Avoid in patients with liver disease due to lactic acidosis risk.
- Temporarily discontinue before iodine contrast imaging and major surgeries.
Side Effects
Common Side Effects
- Nausea, diarrhea, abdominal discomfort.
- Metallic taste.
Less Common Side Effects
- Vitamin B12 deficiency with long-term use.
Rare but Serious Side Effects
- Lactic acidosis: A life-threatening condition; symptoms include weakness, fatigue, and labored breathing.
Drug Interactions
- Increased Risk of Lactic Acidosis:
- Alcohol.
- Iodinated contrast agents.
- Reduced Effectiveness:
- Corticosteroids and diuretics may elevate blood sugar levels.
- Increased Hypoglycemia Risk:
- When combined with insulin or sulfonylureas.
Monitoring Parameters
- Blood glucose levels (fasting and postprandial).
- HbA1c levels (every 3–6 months).
- Kidney function tests (eGFR) annually or more frequently in high-risk patients.
- Vitamin B12 levels periodically with long-term use.
Patient Counseling Points
- Take metformin with meals to minimize stomach upset.
- Report symptoms like severe fatigue, muscle pain, or labored breathing immediately (possible lactic acidosis).
- Limit alcohol consumption to reduce the risk of lactic acidosis.
- Maintain regular follow-ups to monitor kidney function and vitamin B12 levels.
- If a dose is missed, take it with the next meal; do not double the dose.
Use in Children
- Approved for children aged 10 years and older with Type 2 Diabetes.
- Dose adjustments based on weight and response.
Use in Pregnancy
- Considered safe for use during pregnancy for managing blood sugar.
- Often replaced by insulin for optimal glycemic control in some cases.
Use in Elderly
- Use with caution in elderly patients due to the increased risk of renal impairment and lactic acidosis.
- Regular monitoring of kidney function is essential.
FAQs About Metformin
Q1: What is metformin used for?
- It is primarily used for managing Type 2 Diabetes and is also used off-label for PCOS and prediabetes.
Q2: How does metformin work?
- It reduces glucose production in the liver and improves the body’s sensitivity to insulin.
Q3: Can metformin cause weight loss?
- While not a weight-loss drug, it may lead to modest weight reduction in some individuals.
Q4: What are the common side effects?
- Nausea, diarrhea, and stomach upset are common, especially during the initial weeks of treatment.
Q5: Is metformin safe for kidney patients?
- Not recommended for patients with severe kidney impairment (eGFR <30 mL/min/1.73 m²).
Q6: Can metformin cause low blood sugar?
- Rarely, unless combined with other diabetes medications like insulin or sulfonylureas.
Q7: What is lactic acidosis, and how is it linked to metformin?
- A rare but serious condition where lactate builds up in the blood; associated with metformin in patients with kidney, liver, or cardiac issues.
Q8: Can I take metformin while pregnant?
- Yes, it is generally considered safe but may be replaced by insulin in some cases.
Q9: Can metformin cause vitamin B12 deficiency?
- Long-term use can reduce vitamin B12 absorption, requiring supplementation if needed.
Q10: What should I do if I miss a dose?
- Take it with your next meal. Do not double the dose to catch up.
Q11: How long does it take for metformin to work?
- Blood sugar improvements can be seen within a few days, with maximum effects in 4–6 weeks.
Q12: Can I drink alcohol while taking metformin?
- Alcohol increases the risk of lactic acidosis; limit or avoid it.
Q13: Are there alternatives to metformin?
- Yes, alternatives include SGLT-2 inhibitors (e.g., empagliflozin), DPP-4 inhibitors (e.g., sitagliptin), and sulfonylureas (e.g., glimepiride).
Q14: Can metformin be stopped abruptly?
- Avoid stopping without consulting your doctor, as it may lead to uncontrolled blood sugar levels.
Q15: Is metformin available as a generic?
- Yes, it is widely available in generic form, making it affordable for most patients.
