Liraglutide is a once-daily analog of human glucagon-like peptide-1 (GLP-1), sold as Victoza for type 2 diabetes and as Saxenda for chronic weight management. Novo Nordisk built it by attaching a C16 palmitate chain so the peptide rides albumin instead of vanishing in minutes. It is the GLP-1 that opened the obesity-pen era, and it is not weekly semaglutide.

TL;DR

  • Same receptor, different clock. Native GLP-1 lasts about 1.5 minutes after an IV dose. Liraglutide’s plasma half-life after subcutaneous dosing is about 13 hours, which is why the approved products are once daily (Knudsen and Lau, 2019; FDA Victoza label).
  • SCALE Obesity and Prediabetes: 3,731 adults, 56 weeks. Mean weight change was -8.4 kg on liraglutide versus -2.8 kg on placebo. 63.2% versus 27.1% lost at least 5% (Pi-Sunyer et al., 2015).
  • LEADER (diabetes product, not the obesity pen): fewer major cardiovascular events on liraglutide than placebo, hazard ratio 0.87 (Marso et al., 2016).
  • STEP 8: weekly semaglutide beat daily liraglutide on the scale, -15.8% versus -6.4% at 68 weeks (Rubino et al., 2022).
  • FDA products, not a catalog vial. Saxenda is an approved pen. A research vial labeled “liraglutide” is not that product.

What is liraglutide, and how is it different from semaglutide?

Liraglutide is human GLP-1(7-37) with two edits. Lysine 34 becomes arginine so a single lysine remains. Palmitate (C16) is then attached to lysine 26 through a gamma-glutamic acid spacer. That is the albumin tag (Knudsen and Lau, 2019).

Semaglutide is the later weekly analog from the same shop. It swaps alanine 8 for Aib to block DPP-4, and it uses a C18 di-acid instead of palmitate. The chemistry primer is on Peptides 101, and the later incretin comparison is tirzepatide versus semaglutide.

Victoza and Saxenda are the same peptide under two labels. Victoza is the diabetes product. Saxenda is the obesity product.

Why does a C16 chain turn a 2-minute hormone into a daily shot?

Native GLP-1 is cleared by dipeptidyl peptidase-4 (DPP-4) and by the kidney almost as soon as it appears. After intravenous dosing the half-life is about 1.5 minutes, which is why the hormone itself was never a practical drug (Knudsen and Lau, 2019).

Albumin is the reservoir. Palmitate lets liraglutide bind serum albumin reversibly. Bound peptide is shielded from DPP-4 and from glomerular filtration. The free fraction can still hit GLP-1 receptors in pancreas, gut, and brain.

The injection site is the other half. Liraglutide self-associates into heptamers, which slows subcutaneous absorption. The Victoza label puts those facts together: delayed absorption plus albumin binding, plasma half-life about 13 hours, once-daily coverage (FDA Victoza label). The GLP-1 mechanism article covers the receptor pathway.

What did SCALE actually measure?

Pi-Sunyer and colleagues randomized 3,731 adults without type 2 diabetes who had obesity, or overweight plus dyslipidemia or hypertension, to daily liraglutide or placebo for 56 weeks plus diet and activity counseling. Mean weight was 106.2 kg. Mean BMI was 38.3.

Study Who was enrolled Design Main finding
Pi-Sunyer 2015, SCALE Obesity and Prediabetes 3,731 adults without T2D, mean BMI 38.3 Daily liraglutide vs placebo, 56 weeks Mean weight -8.4 kg vs -2.8 kg; 63.2% vs 27.1% lost at least 5%
Marso 2016, LEADER 9,340 adults with T2D and high CV risk Daily liraglutide vs placebo MACE 13.0% vs 14.9%, HR 0.87
Rubino 2022, STEP 8 338 adults with overweight or obesity, no diabetes Weekly semaglutide vs daily liraglutide, 68 weeks Mean weight -15.8% vs -6.4%

The scale moved, and the tails mattered. A 5.6 kg mean gap is the headline. Responder rates were 63.2% versus 27.1% at 5%, and 33.1% versus 10.6% above 10% (Pi-Sunyer et al., 2015).

Gastrointestinal events were the tolerability story. On the 2014 Saxenda label, nausea was 39.3% versus 13.8% on placebo, with diarrhea 20.9% versus 9.9% and vomiting 15.7% versus 3.9%. Discontinuations for adverse events were 9.8% versus 4.3% (FDA Saxenda label). The same label carries a boxed warning about thyroid C-cell tumors in rodents, with unknown relevance in humans, and contraindicates use with a personal or family history of medullary thyroid carcinoma or MEN 2.

What did LEADER add that SCALE did not?

SCALE asked about weight in people without diabetes. LEADER asked about hearts in people with type 2 diabetes.

Marso and colleagues assigned 9,340 adults with type 2 diabetes and high cardiovascular risk to liraglutide or placebo on top of standard care. The primary composite (cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke) occurred in 608 of 4,668 on liraglutide (13.0%) versus 694 of 4,672 on placebo (14.9%). The hazard ratio was 0.87 (95% CI 0.78 to 0.97) (Marso et al., 2016).

That readout belongs to the diabetes product and a high-risk T2D population. It is not a substitute for the obesity-pen trials.

Did weekly semaglutide retire daily liraglutide?

On mean weight, STEP 8 said weekly wins. Rubino and colleagues compared once-weekly semaglutide with once-daily liraglutide for 68 weeks in 338 adults with overweight or obesity and no diabetes. Mean change was -15.8% versus -6.4% (Rubino et al., 2022).

That gap is why Wegovy took the slot Saxenda opened. Liraglutide remains the first approved GLP-1 obesity analog, with a shorter half-life and a smaller mean effect than the weekly successor. Weight tends to return when the pharmacology stops, which is the point of the withdrawal-trial article.

Is a research vial the same as Saxenda?

No. Saxenda is an FDA-approved, multi-dose pen with a defined solution, a boxed warning, and a weight-management indication as an adjunct to diet and activity (FDA Saxenda label). Victoza is the separate diabetes brand of the same analog.

A catalog vial labeled “liraglutide” is not either product. Sequence, salt, sterility, and dose accuracy are the usual gaps. Licensed incretin products, when they are the topic, show up in pharmacy and telehealth channels on the provider directory and the price index.

Handling education for research peptides lives on the reconstitution guide and the calculator. Clinician voices on metabolic peptides are collected on experts.

Bottom line: Liraglutide is a real, FDA-approved daily GLP-1 analog with SCALE weight data and a LEADER cardiovascular readout in type 2 diabetes. Weekly semaglutide later posted a larger mean weight change. A research vial is not Saxenda.

Educational only. Not medical advice. Not a recommendation to use liraglutide, Saxenda, Victoza, or any research-grade GLP-1 peptide.