Liraglutide: GLP-1 Receptor Agonist for Diabetes and Obesity
Liraglutide (Victoza for diabetes, Saxenda for obesity) is a glucagon-like peptide-1 (GLP-1) receptor agonist with 97% sequence homology to native GLP-1. The fatty acid chain extends the half-life to ~13 hours, allowing once-daily dosing.
Approved for type 2 diabetes (glycaemic control), obesity/overweight (BMI ≥30 or ≥27 with comorbidity), and cardiovascular risk reduction in T2DM patients with established CVD. First GLP-1 RA proven to reduce major cardiovascular events (LEADER trial).
Mechanism of Action
Stimulates GLP-1 receptors: glucose-dependent insulin secretion (reduces hypoglycaemia risk), suppresses glucagon, delays gastric emptying (reducing postprandial glucose), and acts centrally to reduce appetite and food intake. Dose-dependent weight loss through central satiety regulation.
Indications & Use
T2DM: as add-on to metformin or other agents; preferred in patients with CVD or high CVD risk. Obesity: BMI ≥30, or ≥27 with comorbidity (diabetes, hypertension, dyslipidaemia). LEADER trial: 13% reduction in MACE in T2DM with established CVD.
Dosage
T2DM (Victoza): start 0.6 mg/day SC, escalate weekly: 1.2 mg/day (1 week), then 1.8 mg/day. Obesity (Saxenda): start 0.6 mg/day, escalate by 0.6 mg/week to target 3.0 mg/day (5 weeks). Administer at any time of day, regardless of meals.
Side Effects
Common: nausea (most common — 15–40%, usually improves in 4–8 weeks), vomiting, diarrhoea. Rare but serious: pancreatitis (discontinue if suspected), medullary thyroid carcinoma (MTC — black box warning in rodents; contraindicated with MTC history). Injection site reactions. Heart rate increase (~2–3 bpm).
Drug Interactions
Insulin: additive hypoglycaemia risk — reduce insulin dose. Sulfonylureas: additive hypoglycaemia — consider dose reduction. Delayed gastric emptying: may affect absorption of oral medications — take critical oral medications (warfarin, antibiotics) when liraglutide effect is lower.
Contraindications
Personal or family history of medullary thyroid carcinoma (MTC), MEN type 2, hypersensitivity. Type 1 diabetes or DKA. Severe renal impairment (limited data). Pregnancy (discontinue when pregnancy detected).
Frequently Asked Questions
How much weight can be lost with liraglutide?
In the SCALE trial (Saxenda 3 mg/day), average weight loss was ~8% of body weight (vs. ~2.6% placebo) over 56 weeks. About 63% of patients lost ≥5% of body weight. Weight loss is greatest in the first 6 months and requires concurrent lifestyle modification.
Is there a risk of thyroid cancer?
A black box warning exists for medullary thyroid carcinoma (MTC) based on rodent studies. To date, no increased MTC risk has been conclusively demonstrated in humans. Liraglutide is contraindicated in patients with personal or family history of MTC or MEN2 syndrome.
What is the difference between liraglutide and semaglutide?
Both are GLP-1 receptor agonists. Semaglutide has greater potency and produces greater weight loss (~15% vs. ~8% with liraglutide). Semaglutide also has oral formulation (Rybelsus). Semaglutide (Ozempic/Wegovy) is now generally preferred due to superior efficacy.
References
- EMA Victoza/Saxenda SPC 2023
- LEADER trial: Marso SP et al. NEJM 2016
- SCALE trial: Pi-Sunyer X et al. NEJM 2015
Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice.