Metformin Nursing Considerations

Metformin is a biguanide antidiabetic medication commonly prescribed as the first-line treatment for type 2 diabetes mellitus. It decreases glucose production in the liver and improves insulin sensitivity in body tissues.

Generic names: Metformin hydrochloride

Brand names: Glucophage, Glucophage XR, Fortamet, Glumetza, Riomet

Pharmacologic class: Biguanide

Therapeutic class: Antidiabetic, Oral hypoglycemic agent

Mechanism of action: Metformin reduces hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

Indications for use: Type 2 diabetes mellitus management, prediabetes, polycystic ovary syndrome (PCOS), and weight management in conjunction with lifestyle modifications.

Precautions and contraindications: Renal impairment (eGFR < 30 mL/min), acute or chronic metabolic acidosis, severe hepatic dysfunction, and hypersensitivity to metformin. Use cautiously in elderly patients and those undergoing radiologic studies with iodinated contrast materials.

Drug Interactions

• ACE inhibitors and ARBs may increase the risk of hypoglycemia
• Alcohol may increase the risk of lactic acidosis
• Cationic drugs (amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, vancomycin) may reduce metformin elimination.
• Carbonic anhydrase inhibitors (topiramate, zonisamide) may increase the risk of lactic acidosis.
• Corticosteroids, thiazide diuretics, and thyroid products may decrease metformin’s effectiveness.

Adverse Effects

• Gastrointestinal disturbances: diarrhea, nausea, vomiting, abdominal bloating, flatulence
• Metallic taste in the mouth
• Vitamin B12 deficiency with long-term use
• Hypoglycemia (rare when used alone)
• Lactic acidosis (rare but serious)
• Weight loss or anorexia
• Weakness, myalgia
• Headache, dizziness

Administration Considerations

Available preparations: Immediate-release tablets (500mg, 850mg, 1000mg), extended-release tablets, oral solution

Adult dosages: Initial: 500mg twice daily or 850mg once daily with meals. Maximum daily dose: 2550mg divided into 2-3 doses.

Onset of action: 3-5 days
Peak effect: 2-3 weeks
Duration: 24 hours

Nursing Considerations for Metformin

Related Nursing Diagnoses

• Risk for unstable blood glucose
• Imbalanced nutrition
• Risk for acute confusion related to hypoglycemia
• Knowledge deficit related to medication regimen
• Risk for injury related to hypoglycemic episodes

Nursing Assessment

1. Assess blood glucose levels regularly, including fasting and postprandial readings.
2. Monitor renal function through BUN and creatinine levels, as the kidneys clear metformin.
3. Assess for signs and symptoms of lactic acidosis: weakness, fatigue, muscle pain, difficulty breathing, abdominal pain, dizziness.
4. Evaluate the patient’s understanding of diabetes management and medication regimen.
5. Monitor weight and dietary intake, as metformin may affect appetite.

Nursing Interventions

1. Administer metformin with meals to reduce gastrointestinal side effects.
2. Monitor for signs of vitamin B12 deficiency, especially in long-term use.
3. Assess for and document any side effects, particularly gastrointestinal disturbances.
4. Regularly monitor blood glucose levels and maintain accurate records.
5. Discontinue metformin 48 hours before and after procedures using iodinated contrast materials.

Patient Teaching Associated with Metformin

1. Take medication with meals to minimize gastrointestinal upset.
2. Do not crush or break extended-release tablets; swallow them whole.
3. Maintain consistent carbohydrate intake throughout the day.
4. Monitor blood glucose regularly and keep a log of readings.
5. Report symptoms of lactic acidosis immediately: unusual muscle pain, difficulty breathing, unusual sleepiness, slow/irregular heartbeat.
6. Avoid excessive alcohol consumption while taking metformin.
7. Continue regular exercise and follow the prescribed diet plan.
8. Carry glucose tablets or quick-acting sugar source for potential hypoglycemic episodes.
9. Wear medical identification indicating diabetes and metformin use.
10. Store medication at room temperature away from moisture and heat.

This is not an all-inclusive list of possible drug interactions, adverse effects, precautions, nursing considerations, or patient instructions. Please consult with a pharmacist for complete information.

References

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