Glucagon-like peptide-1 receptor agonists / incretin mimetics
GLP-1 receptor agonists
Injectable (and oral semaglutide) drug class for type 2 diabetes and, at higher doses, weight management. Slow gastric emptying, augment glucose-dependent insulin secretion, and suppress glucagon.
Indications
- Type 2 diabetes mellitus — usually as second- or third-line therapy after metformin, often when cardiovascular risk reduction or weight loss is also a goal
- Weight management in adults with obesity (semaglutide 2.4 mg weekly as Wegovy; liraglutide 3.0 mg daily as Saxenda; tirzepatide as Mounjaro per current NICE / NHS criteria)
- Cardiovascular risk reduction in established CVD with T2DM (semaglutide, liraglutide, dulaglutide)
Dosing
Examples
Semaglutide SC: start 0.25 mg once weekly, titrate to 0.5–1.0 mg weekly (Ozempic) or up to 2.4 mg weekly (Wegovy). Liraglutide SC: start 0.6 mg daily, titrate weekly to 1.8 mg (Victoza) or 3.0 mg (Saxenda). Always titrate slowly to limit GI side effects.
Oral semaglutide (Rybelsus)
Take on an empty stomach with no more than 120 mL of plain water; wait at least 30 minutes before food, drink, or other oral medicines.
Always confirm doses against the current BNF — this summary is for study, not prescribing.
Monitoring
- HbA1c at 3–6 months and periodically thereafter (T2DM)
- Weight, BMI and waist circumference (obesity indication)
- Renal function in those with CKD or volume depletion
- Pancreatitis vigilance — abdominal pain history
- Gallbladder symptoms during weight-loss regimens
Contraindications
- Personal or family history of medullary thyroid carcinoma or MEN2 (precaution)
- Severe gastroparesis
- Pregnancy and breastfeeding
- Diabetic ketoacidosis (not a substitute for insulin)
Important interactions
- Insulin and sulfonylureas — increased hypoglycaemia risk; reduce dose at initiation
- Drugs requiring rapid GI absorption (some antibiotics, levothyroxine, oral contraceptives at higher BMIs) — slowed gastric emptying may affect absorption; counsel and monitor
- Warfarin — small risk of altered INR around dose changes; monitor as usual
Counselling points
- Inject subcutaneously into abdomen, thigh, or upper arm; rotate sites
- Refrigerate before first use; in-use storage per the SmPC (often up to 6 weeks at room temperature)
- Nausea is the most common side effect — eat smaller, slower meals; titrate slowly
- Stop and seek urgent help for severe abdominal pain (pancreatitis) or gallbladder pain
- Use additional contraception around weight loss and consider that absorption of oral contraceptives may be reduced — discuss with prescriber
- Continue cardiovascular risk-factor management — these are not a substitute for lifestyle change
Red flags
- Acute pancreatitis — severe upper abdominal pain radiating to the back; stop the drug urgently
- Severe ongoing nausea or vomiting → risk of dehydration and AKI
- Pregnancy — stop and refer to a diabetes-in-pregnancy team
Practice for the CRA
Drug-specific questions, calculations, and full mock exams aligned to the GPhC Common Registration Assessment.