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Sulphonylurea Pregnancy: Contraindicated — risk of neonatal hypoglycaemia. Use insulin in pregnancy.

Glimepiride

Brand names: Amaryl

Adult dose

Dose: Starting: 1–2mg OD; maintenance 1–4mg OD; maximum 6mg OD in exceptional cases
Route: Oral
Frequency: Once daily with breakfast (or first main meal)
Max: 6mg OD
Long-acting sulphonylurea — once-daily dosing. Lower risk of hypoglycaemia compared to glibenclamide. NICE NG28: sulphonylureas are third-line after metformin + SGLT2i or DPP-4i when HbA1c inadequately controlled.

Paediatric dose

Route: Oral
Frequency: Once daily
Max: Not applicable
Not licensed under 18 years. Seek specialist opinion.

Dose adjustments

Renal

eGFR 30–60: use with caution and reduce dose; eGFR <30: avoid (risk of prolonged hypoglycaemia due to active metabolite accumulation).

Hepatic

Moderate-severe hepatic impairment: avoid — impaired glycogenolysis and drug metabolism both increase hypoglycaemia risk.

Clinical pearls

  • Antidote for sulphonylurea-induced hypoglycaemia: if conscious — oral glucose; if unconscious — IV dextrose 10% 150–200mL (preferred over glucagon for sulphonylurea OD as it avoids rebound hypoglycaemia from further insulin secretion stimulus)
  • Prolonged hypoglycaemia (up to 24+ hours) with long-acting sulphonylureas — patients may need hospital admission and dextrose infusion
  • Octreotide 50–100 micrograms SC 8-hourly used as antidote in sulphonylurea overdose to suppress insulin secretion
  • Sick day rules: withhold during acute illness — risk of hypoglycaemia when eating poorly

Contraindications

  • Type 1 DM
  • Diabetic ketoacidosis
  • Severe renal impairment (eGFR <30)
  • Severe hepatic impairment
  • Porphyria
  • Hypersensitivity to sulphonylureas or sulphonamides

Side effects

  • Hypoglycaemia (dose-related, prolonged episodes possible)
  • Weight gain
  • GI upset (nausea, diarrhoea)
  • Hyponatraemia (SIADH — rare)
  • Photosensitivity rash
  • Blood dyscrasias (rare)

Interactions

  • Alcohol — unpredictable hypoglycaemia; flushing reaction
  • Fluconazole, miconazole — inhibit CYP2C9 → increase glimepiride levels → hypoglycaemia
  • Rifampicin — CYP2C9 induction → reduced efficacy
  • Beta-blockers — mask hypoglycaemia symptoms
  • ACE inhibitors, salicylates — additive hypoglycaemic effect

Monitoring

  • Blood glucose (hypoglycaemia monitoring)
  • HbA1c 3–6 monthly
  • Renal function (annually)
  • Weight

Reference: BNFc; BNF 90; NICE NG28 (Type 2 DM). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways