Exenatide (Byetta) GLP1 agonist 💊
💉 Administration: Each dose should be given by subcutaneous injection into the thigh, abdomen, or upper arm. Injection sites should be rotated to reduce risk of local irritation.
📘 About
- Always check the BNF for latest prescribing advice.
- Exenatide is a GLP-1 receptor agonist used as an add-on therapy for patients with T2DM who have inadequate glycaemic control despite maximally tolerated metformin and/or sulfonylurea therapy.
- It is available in both intermediate-release (twice daily) and modified-release (once weekly) formulations.
⚙️ Mode of Action
- GLP-1 analogue that mimics the incretin hormone.
- Stimulates glucose-dependent insulin secretion.
- Suppresses inappropriate glucagon secretion.
- Slows gastric emptying → promotes satiety and weight loss.
💊 Indications & Example Doses
- T2DM with metformin and/or sulfonylurea (± pioglitazone):
- Intermediate release: 5 micrograms SC BD for ≥1 month, then increase to 10 micrograms SC BD if required. Administer within 1 hour before two main meals (≥6 hours apart).
- Modified release: 2 mg SC once weekly, regardless of meals.
- T2DM with basal insulin (± metformin/pioglitazone):
- Intermediate release as above: start 5 micrograms SC BD, may increase to 10 micrograms BD.
🔄 Interactions
- Risk of hypoglycaemia when combined with sulfonylureas or insulin – dose reduction of these agents may be needed.
- Delays gastric emptying → may alter absorption of oral medicines (especially narrow therapeutic index drugs).
⚠️ Cautions
- Do not reduce insulin too rapidly when switching/adding therapy (risk of DKA).
- Weight loss can be problematic in frail or elderly patients.
- Stop if renal function deteriorates (risk of accumulation and adverse effects).
- Monitor for symptoms of pancreatitis (severe abdominal pain radiating to the back).
🚫 Contraindications
- Moderate to severe renal impairment (eGFR <30 mL/min/1.73m²).
- History of severe gastrointestinal disease (e.g., gastroparesis).
💥 Side Effects
- GI: Nausea, vomiting, diarrhoea, constipation, abdominal discomfort.
- Weight loss (can be beneficial but may be excessive in older adults).
- Hypoglycaemia (especially with sulfonylurea or insulin).
- Slows gastric emptying → can worsen gastroparesis.
- Rare: Pancreatitis, injection-site reactions.
📖 References
📝 Revisions
- September 2025 – Expanded with renal cautions, pancreatitis risk, and UK NICE context.
