What it is
Liraglutide is a 31-amino-acid peptide drug built on GLP-1(7-37), the active form of glucagon-like peptide-1 — a hormone the gut releases after a meal. The Victoza label describes two changes to the natural hormone:
- Arginine for lysine at position 34 — a single swapped amino acid, which is why the label calls it 97% homologous to human GLP-1;
- A 16-carbon fatty acid (palmitic acid) attached through a glutamic-acid spacer to the lysine at position 26.
The peptide chain is made in baker's yeast using recombinant DNA; the fatty acid is attached afterwards. The finished molecule weighs 3,751.2 daltons.
Why the fatty-acid tail matters
Natural GLP-1 barely survives in the blood. The label gives its half-life as 1.5 to 2 minutes, because two enzymes — DPP-4 and neutral endopeptidase — cut it almost as soon as it is released. Liraglutide resists both, and its half-life after an injection under the skin is 13 hours: roughly 400 to 500 times longer.
The label credits three mechanisms: molecules clumping together at the injection site so they are absorbed slowly, binding to blood proteins (more than 98% bound), and resistance to enzymatic breakdown. That is what turned a hormone lasting minutes into a once-a-day medicine — and the same idea, pushed further, produced once-weekly semaglutide.
How it works
Liraglutide switches on the GLP-1 receptor. In the pancreas that increases insulin release only when blood sugar is raised — the label notes that insulin release subsides as blood sugar returns toward normal — and lowers glucagon release in the same glucose-dependent way. It also slows stomach emptying. The Saxenda label adds that GLP-1 receptors sit in brain areas that regulate appetite, and that in animal studies liraglutide reached the hypothalamus.
What it is approved for
| Brand | Approved use (current US label) | Dose range the label describes |
|---|---|---|
| Victoza (2010) | Type 2 diabetes, adults and children 10+; reducing cardiovascular events in type 2 diabetes with heart disease | 0.6–1.8 mg once daily |
| Saxenda (2014) | Weight management in adults with obesity, or overweight plus a weight-related condition; children 12+ above 60 kg with obesity | Titrated to 3 mg once daily |
| Xultophy (2016) | Type 2 diabetes — a fixed combination with insulin degludec | Combination product |
Both single-ingredient pens hold the same solution: 6 mg per mL, 18 mg per pen. The brands differ by indication and dose, not by what is in the cartridge.
The trial record
Heart outcomes — LEADER. 9,340 people with type 2 diabetes and established heart disease were randomised to liraglutide or placebo on top of usual care. The hazard ratio for a first heart attack, stroke or cardiovascular death was 0.87 (95% CI 0.78–0.97). The Victoza label carries that result as an approved claim.
Weight — the Saxenda trials. Three 56-week, placebo-controlled studies, each with diet and activity counselling in both arms:
| Study | People | Weight change, liraglutide 3 mg | Placebo | Lost ≥5% of body weight |
|---|---|---|---|---|
| 1 — obesity or overweight with a condition | 3,731 | −7.4% | −3.0% | 62.3% vs 34.4% |
| 2 — with type 2 diabetes | 635 | −5.4% | −1.7% | 49.0% vs 16.4% |
| 3 — after ≥5% loss on a diet run-in | 422 | −4.9% | +0.3% | 44.2% vs 21.7% |
Two details from the label that summaries usually drop: 27% of the liraglutide group and 35% of the placebo group stopped the study drug early, and Study 3 admitted only people who had already lost 5% by dieting, so the label warns its results "may not reflect those expected in the general population."
Safety
Both labels open with a boxed warning: liraglutide causes thyroid C-cell tumours in rats and mice at clinically relevant exposures, and whether it does so in humans has not been determined. It is contraindicated with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2. The listed serious reactions include acute pancreatitis, gallbladder disease, kidney injury from dehydration, severe gastrointestinal reactions and aspiration during anaesthesia. The most common are nausea, diarrhoea, vomiting, constipation and reduced appetite.
Where it stands
FDA application data list 11 liraglutide applications on 2026-09-24: the three brand products above and eight generic applications, all marketed on prescription, the earliest approved on 23 December 2024. PubMed indexes 5,938 records, 576 tagged as randomised controlled trials — a human evidence base measured in tens of thousands of trial participants, unlike most compounds in this library.
Related reading
Liraglutide's successors are semaglutide, the once-weekly GLP-1 analogue, and tirzepatide, which adds a second hormone receptor. GLP-1 shares 14 of its first 29 amino acids with glucagon, the hormone it was named after. For the size line that keeps liraglutide a peptide, see how US law separates peptides from proteins.