Makindo Medical Notes

Metformin does not cause hypoglycaemia. ⚠️ Consider stopping if creatinine is elevated or eGFR <45 ml/min/1.73m². 🛑 Omit 48 h before IV contrast administration. 💊 If GI side effects occur with standard-release, consider trial of modified-release formulation.

💊 About

• Always check the BNF or local formulary for full prescribing advice.
• Biguanide class agent. Improves glycaemic control without weight gain.

⚙️ Mode of Action

• ↓ Hepatic glucose production (gluconeogenesis suppression).
• ↑ Peripheral glucose uptake (particularly skeletal muscle).
• ↑ Insulin sensitivity (reduces insulin resistance).
• ↓ Intestinal absorption of glucose (minor effect).

📌 Dose

• Typical range: 500–2000 mg/day orally, e.g. 1 g twice daily.
• Initial titration: start low and increase gradually to minimise GI side effects.
• If eGFR <45 ml/min/1.73m² → review dose, avoid initiation if <30.

🧾 Prescribing Advice

• Start: 500 mg OD with food for 1 week → then BD → then TDS as tolerated (max 2 g/day, licensed max 3 g/day).
• Titrate slowly, waiting until patient is side-effect free before each increase.
• If GI intolerance: reduce to highest tolerated dose; consider MR preparation.
• Some sensitive patients may tolerate very slow titration from as little as 125 mg daily.

🎯 Indications

• Type 2 Diabetes Mellitus — especially if overweight/obese.
• Polycystic Ovary Syndrome (PCOS).
• Adjunct in insulin-resistant states (e.g., NASH, insulin-requiring T2DM).
• Can be used in combination with sulfonylureas or insulin.

🚫 Contraindications

• Severe cardiac failure, liver failure, recent MI, severe dehydration, or shock.
• Renal impairment: avoid if creatinine >150 µmol/L or eGFR <30. Use with caution if eGFR 30–45.
• Avoid in pregnancy and breastfeeding.
• Avoid with alcohol misuse (↑ risk lactic acidosis).
• Withhold for 48 h before and after IV contrast.

⚠️ Side Effects

• GI upset: bloating, nausea, diarrhoea.
• Weight loss and anorexia (may be beneficial).
• Vitamin B12 deficiency with long-term use → check if anaemia or neuropathy develops.
• Lactic acidosis (rare but serious) — usually in presence of renal, cardiac, or hepatic dysfunction.

📚 References

• Summary of Product Characteristics
• BNF: Metformin