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Liraglutide

Liraglutide

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Acylated GLP-1 receptor agonist — a long-acting analog of human glucagon-like peptide-1 (GLP-1) engineered with a C-16 fatty acid chain enabling albumin binding and once-daily subcutaneous dosing for type 2 diabetes and chronic weight management.

Quick Facts

Property Value
Also Known As Victoza (T2D, 1.8 mg), Saxenda (obesity, 3.0 mg), NN2211
Category Metabolic / Weight Loss / GLP-1 Receptor Agonist
Sequence Modified human GLP-1 (7-37) with Arg34 substitution and C-16 palmitic (palmitoyl) fatty acid attached via glutamic acid spacer at Lys26
Molecular Weight 3751.2 Da
Molecular Formula C172H265N43O51
PubChem CID 16134956
Administration SubQ (once daily)
Typical Dose Range Victoza: 0.6-1.8 mg/day (T2D); Saxenda: 0.6-3.0 mg/day titrated (obesity)
Half-Life ~13 hours (albumin binding via C-16 fatty acid chain)
Storage Refrigerated (2-8C) before first use; room temperature (15-30C) for up to 30 days after first use. Protect from light. Do not freeze.
FDA Status APPROVED — Victoza (T2D, January 2010), Saxenda (chronic weight management, December 2014). CV risk reduction indication added to Victoza (2017) based on LEADER trial.
WADA Status Not prohibited (FDA-approved prescription medication)

Mechanism of Action

Liraglutide is a 97% sequence-homologous analog of native human GLP-1 (7-37) that acts as a full agonist at the GLP-1 receptor (GLP1R, UniProt P43220). The critical structural modification — attachment of a C-16 palmitic acid (palmitoyl) fatty acid chain via a glutamic acid spacer at position 26 (replacing the native lysine with arginine at position 34 to prevent acylation at that site) — enables reversible non-covalent binding to serum albumin. This albumin binding serves three functions: (1) it shields liraglutide from degradation by dipeptidyl peptidase-4 (DPP-4), (2) it reduces renal clearance, and (3) it creates a circulating depot that extends the plasma half-life from approximately 2 minutes (native GLP-1) to approximately 13 hours, enabling once-daily subcutaneous injection (PMID-26597252).

Upon binding the GLP-1 receptor (a class B G protein-coupled receptor), liraglutide activates the Gs-adenylyl cyclase-cAMP-PKA signaling cascade across multiple target tissues. In pancreatic beta cells, this potentiates glucose-dependent insulin secretion (i.e., insulin is released only when glucose is elevated, minimizing hypoglycemia risk), promotes beta-cell proliferation, and inhibits apoptosis. In pancreatic alpha cells, liraglutide suppresses glucagon secretion in a glucose-dependent manner. In the central nervous system, it activates GLP-1 receptors in the hypothalamic arcuate nucleus and brainstem nucleus tractus solitarius, promoting satiety and reducing food intake — the mechanism primarily responsible for weight loss. In the gastrointestinal tract, it delays gastric emptying, contributing to postprandial glucose control and satiety (PMID-26597252).

The cardiovascular benefits demonstrated in the LEADER trial (PMID-27295427) appear to involve direct and indirect mechanisms: reduced inflammation (lower hsCRP), improved endothelial function, modest reductions in blood pressure and atherogenic lipids, and potential direct cardioprotective effects via GLP-1R expressed on cardiomyocytes and vascular endothelium.

Comparison to semaglutide: Both are acylated GLP-1 analogs, but semaglutide uses a longer C-18 fatty di-acid chain with additional modifications (Aib8 substitution) that confer greater albumin affinity and DPP-4 resistance, extending its half-life to ~168 hours (enabling weekly dosing). Semaglutide also achieves superior weight loss (-15.8% vs -6.4% for liraglutide in the head-to-head STEP 8 trial), though both act through the same GLP-1R-mediated pathways.

Key Research Areas

  1. Cardiovascular outcomes in T2D — The LEADER trial (n=9,340) demonstrated a 13% reduction in 3-point MACE (HR 0.87, p=0.01), 22% reduction in CV death (HR 0.78, p=0.007), and 15% reduction in all-cause mortality, establishing liraglutide as the first GLP-1 RA with proven cardiovascular superiority (PMID-27295427)
  2. Chronic weight management — The SCALE Obesity trial (n=3,731) showed -8.0% mean weight loss at 56 weeks with liraglutide 3.0 mg vs -2.6% with placebo, with 63.2% achieving >=5% weight loss (PMID-26132939)
  3. Weight maintenance after dietary intervention — The SCALE Maintenance trial demonstrated that liraglutide prevents weight regain and promotes additional -6.2% weight loss after an initial -6.0% diet-induced loss (PMID-23812094)
  4. Prediabetes reversal — In the SCALE trial, liraglutide reduced progression from prediabetes to T2D by 80% over 3 years (PMID-26132939)
  5. Nephroprotection — LEADER trial showed 22% reduction in new or worsening nephropathy (HR 0.78, p=0.003), primarily driven by reduced new-onset macroalbuminuria (PMID-27295427)
  6. Pooled safety profile — Meta-analysis of 6 RCTs (n=5,218) confirmed -5.25 kg weight loss vs placebo with acceptable safety; GI events are the primary tolerability concern (PMID-32127832)

Evidence Level Summary

Evidence Type Count Notes
Human RCTs 3 LEADER (CV outcomes, n=9,340), SCALE Obesity (n=3,731), SCALE Maintenance (n=422)
Human observational 0 —
Animal in vivo 0 —
In vitro 0 —
Systematic reviews 1 Meta-analysis of 6 RCTs in obese non-diabetic individuals (n=5,218)
Narrative reviews 1 Comprehensive PK/PD review of clinical pharmacology

Note: As an FDA-approved medication with extensive Phase I-IV clinical data, liraglutide has a substantially larger evidence base than most peptides in this vault. The 5 studies above represent landmark trials; the full liraglutide literature encompasses hundreds of clinical studies including the LEAD 1-6 trials, SCALE Diabetes, SCALE Sleep Apnea, and numerous real-world evidence studies.

Clinical Applications

  • Weight Management — FDA-approved (Saxenda 3.0 mg) for chronic weight management in adults with BMI >=30 or >=27 with weight-related comorbidity
  • Fat Loss — Clinically significant fat mass reduction with preferential visceral fat loss
  • Type 2 Diabetes — FDA-approved (Victoza 1.2-1.8 mg) for glycemic control; also approved for CV risk reduction in T2D with established CVD
  • Metabolic Syndrome — Improvements across multiple metabolic parameters (glucose, lipids, blood pressure, waist circumference)

Protocols Using This Peptide

Ageless Peps Products

Note: A Liraglutide Vial (WC ID 701, $45) exists in the Ageless Peps WooCommerce catalog in DRAFT status. Product note will be created when the product is published. As an FDA-approved prescription medication, regulatory considerations for retail sale differ significantly from RUO peptides — clinical-use labeling via wholesale.agelesspeps.com may be more appropriate.

Dosing Reference

FDA-Approved Dosing (Prescribing Information)

Indication Starting Dose Titration Target Dose Route Frequency
T2D (Victoza) 0.6 mg Increase to 1.2 mg after 1 week; may increase to 1.8 mg if needed 1.2-1.8 mg SubQ Once daily (any time, independent of meals)
Obesity (Saxenda) 0.6 mg Increase by 0.6 mg weekly over 4 weeks 3.0 mg SubQ Once daily (any time, independent of meals)

Titration Schedule (Saxenda)

Week Dose
Week 1 0.6 mg/day
Week 2 1.2 mg/day
Week 3 1.8 mg/day
Week 4 2.4 mg/day
Week 5+ 3.0 mg/day (maintenance)

Dose escalation rationale: Gradual titration is critical to minimize GI adverse events (nausea, vomiting). If a patient cannot tolerate a dose increase, delay for an additional week before retrying. Discontinue if 3.0 mg cannot be tolerated. Per FDA labeling, Saxenda should be discontinued if >=4% weight loss is not achieved by 16 weeks at 3.0 mg.

Cycling

Liraglutide is FDA-approved for chronic (indefinite) use — it is not cycled. Weight regain is expected upon discontinuation, consistent with obesity being a chronic disease requiring ongoing treatment. The SCALE Maintenance trial demonstrated that continuous treatment is necessary to sustain weight loss (PMID-23812094).

Contraindications & Safety

BLACK BOX WARNING

Thyroid C-Cell Tumors: Liraglutide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors (adenomas and carcinomas) at clinically relevant exposures in both genders of rats and mice. It is unknown whether liraglutide causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans. Liraglutide is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

  • Contraindications:

    • Personal or family history of medullary thyroid carcinoma (MTC)
    • Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
    • Known hypersensitivity to liraglutide or any product component
    • Pregnancy (Category X — teratogenic in animal studies)
    • Do not use Victoza and Saxenda concurrently
    • Do not use with other GLP-1 receptor agonists concurrently
    • Do not use with insulin (Saxenda)

  • Common side effects:

    • Nausea (40% at 3.0 mg, usually transient, peaks in first 4-8 weeks)
    • Diarrhea (21%)
    • Vomiting (16%)
    • Constipation (14%)
    • Headache (14%)
    • Decreased appetite (10%)
    • Dyspepsia (9%)
    • Injection site reactions (13%)

  • Serious adverse events (rare but monitored):

    • Acute pancreatitis (discontinue if suspected; do not restart)
    • Gallbladder disease (cholelithiasis, cholecystitis — incidence increases with rapid weight loss)
    • Acute kidney injury (usually in setting of dehydration from GI adverse events)
    • Suicidal ideation and behavior (FDA monitoring; causal relationship not established)
    • Hypoglycemia (rare as monotherapy; risk increases with sulfonylureas or insulin)
    • Anaphylaxis and angioedema (rare)
    • Increased heart rate (mean increase 2-3 bpm)

  • Drug interactions:

    • Sulfonylureas / insulin: increased hypoglycemia risk — dose reduction of sulfonylurea or insulin may be needed
    • Oral medications: delayed gastric emptying may affect absorption; take narrow therapeutic index oral medications with caution
    • Warfarin: monitor INR more frequently when initiating or changing liraglutide dose

  • Pregnancy/nursing: Contraindicated in pregnancy (Category X). Discontinue at least 2 months before planned pregnancy. Unknown if excreted in human milk; not recommended during breastfeeding. Pooled human pregnancy-exposure data (Parker 2025, PMID 40329607, Diabetes Obes Metab 2025;27(8):4102-4108): Class-level review of unplanned pregnancies occurring during FDA- and EMA-submitted regulatory clinical trials for GLP-1 RAs (including liraglutide). Incidence of congenital abnormalities appeared relatively low in the pooled dataset, though sample size is limited and evidence in planned pregnancies is lacking. Authors call for prospective pregnancy registries. Standard clinical guidance unchanged — discontinue upon pregnancy awareness. Liraglutide's shorter half-life (~13 hours) permits a shorter pre-conception washout than semaglutide; consult current Saxenda/Victoza prescribing information for specific guidance.

  • Special populations:

    • Renal impairment: No dose adjustment for mild-to-moderate. Use caution in severe impairment (limited data). Monitor renal function in patients reporting GI adverse events due to dehydration risk.
    • Hepatic impairment: No dose adjustment for mild-to-moderate. Not recommended in severe hepatic impairment (not studied).
    • Pediatric: Saxenda approved for adolescents >=12 years with obesity (2020). Victoza approved for children >=10 years with T2D (2019).
    • Geriatric: No dose adjustment needed. Clinical experience in patients >75 years is limited.

Synergistic Combinations

Note on clinical context: As an FDA-approved prescription medication, liraglutide combination strategies are guided by prescribing information and clinical guidelines, not the off-label stacking approaches used with research peptides.

  • Metformin + Liraglutide — Complementary mechanisms (hepatic glucose output reduction + incretin effect); standard first-line combination in T2D
  • SGLT2 inhibitors + Liraglutide — Additive CV and renal benefits; mechanistically complementary (renal glucose excretion + GLP-1 agonism)
  • Lifestyle intervention + Liraglutide — SCALE Maintenance demonstrated enhanced outcomes when liraglutide is added after dietary weight loss (PMID-23812094)

Important clinical note regarding semaglutide: Semaglutide (Ozempic/Wegovy, weekly dosing) has largely superseded liraglutide (Victoza/Saxenda, daily dosing) for most clinical applications due to greater dosing convenience and superior weight loss efficacy. In the head-to-head STEP 8 trial, semaglutide 2.4 mg weekly produced -15.8% weight loss vs -6.4% for liraglutide 3.0 mg daily. However, liraglutide remains an important clinical option: it was the first GLP-1 RA approved specifically for obesity (Saxenda, 2014), has a longer post-marketing safety record, may be preferred when a shorter half-life is clinically desirable (e.g., peri-procedural settings, patients concerned about prolonged adverse effects), and remains widely available.

Related Research

PMID Title Year Study Type
PMID-27295427 Liraglutide and Cardiovascular Outcomes in Type 2 Diabetes 2016 RCT
PMID-26132939 A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management 2015 RCT
PMID-32127832 Efficacy and safety of liraglutide in obese, non-diabetic individuals: systematic review and meta-analysis 2019 Systematic Review / Meta-Analysis
PMID-26597252 Liraglutide in Type 2 Diabetes Mellitus: Clinical Pharmacokinetics and Pharmacodynamics 2016 Narrative Review
PMID-23812094 Weight maintenance and additional weight loss with liraglutide after low-calorie-diet-induced weight loss: the SCALE Maintenance randomized study 2013 RCT
PMID-40329607 – Parker GLP-1 Pregnancy Regulatory Safety Data Parker: GLP-1 RA Use in Pregnancy — Pooled Regulatory Trial Safety Data 2025 Regulatory review

References

  • PMID-27295427 — Marso SP et al. LEADER trial. NEJM 2016.
  • PMID-26132939 — Pi-Sunyer X et al. SCALE Obesity trial. NEJM 2015.
  • PMID-32127832 — Zhang P et al. Liraglutide safety meta-analysis. Afr Health Sci 2019.
  • PMID-26597252 — Jacobsen LV et al. PK/PD review. Clin Pharmacokinet 2016.
  • PMID-23812094 — Wadden TA et al. SCALE Maintenance. Int J Obes 2013.
  • PMID-40329607 — Parker CH et al. GLP-1 RA use during pregnancy: regulatory clinical trials safety data. Diabetes Obes Metab. 2025;27(8):4102-4108.

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