GLP-1 RECEPTOR AGONIST

Liraglutide: The First Daily GLP-1

A 31-amino-acid GLP-1 analogue with a C16 fatty-acid tail. Approved as Victoza (T2D) and Saxenda (obesity) before semaglutide replaced it as first-line.

🔬 HighPeptides perspective: Liraglutide is now second-line for most GLP-1 use — once-daily injections lost to semaglutide's once-weekly schedule. But it remains the most-studied GLP-1 in pediatric and adolescent obesity, where weekly dosing has less long-term data.
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Mean weight loss at 56 weeks (SCALE Obesity, 3.0 mg)
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Of patients lost ≥5% body weight (SCALE Obesity)
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Typical HbA1c reduction in T2D (LEAD trials)

How It Works

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GLP-1 receptor agonist

Binds the GLP-1 receptor in pancreas, gut, and brain. Triggers glucose-dependent insulin secretion (low hypoglycemia risk) and suppresses glucagon.

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Slows gastric emptying

Food stays in the stomach longer, increasing satiety and reducing post-meal glucose spikes. The mechanism behind most GI side effects.

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Central appetite suppression

Acts on hypothalamic GLP-1 receptors to reduce hunger and food reward. Patients report eating less without conscious effort.

Once-daily half-life

C16 fatty-acid acylation extends half-life to ~13 hours via albumin binding. Requires daily subcutaneous injection — semaglutide's C18 diacid extends to ~7 days.

What the Data Shows

SCALE Obesity (no T2D)
3.0 mg/day, 56 weeks, n=3,731
−8.4 kg
SCALE Insulin (T2D + insulin)
3.0 mg/day, 56 weeks
−5.8%
LEAD-3 monotherapy (T2D)
1.8 mg/day, 52 weeks
−1.1% HbA1c
SCALE Sleep Apnea
3.0 mg/day, 32 weeks
−12.2 AHI
Semaglutide STEP-1 (comparison)
2.4 mg/week, 68 weeks
−14.9%

Daily Dosing Schedule

TimeCompounds
Week 10.6 mg/day SC injection (any time, with or without food)
Week 21.2 mg/day
Week 31.8 mg/day (Victoza max for T2D)
Week 42.4 mg/day
Week 5+3.0 mg/day (Saxenda max for obesity)

Key Takeaways

✅ What We Know
  • Mean 8.4 kg (≈8%) weight loss at 56 weeks at 3.0 mg/day in non-diabetics (SCALE Obesity, NEJM 2015).
  • Reduces HbA1c by ~1.0–1.5% in T2D at 1.2–1.8 mg/day (LEAD program).
  • Approved for adolescents (12+) with obesity — broader pediatric data than semaglutide.
  • Reduces apnea-hypopnea index by ~12 events/hour in obese OSA patients.
  • Cardiovascular benefit shown in LEADER trial (13% MACE reduction in T2D + high CV risk).
  • Same drug class as semaglutide, tirzepatide — same dose-titration logic for GI tolerability.
⚠️ What We Don't Know
  • Long-term (>5 yr) head-to-head vs semaglutide on weight maintenance.
  • Whether daily vs weekly dosing changes adherence-adjusted real-world outcomes meaningfully.
  • Optimal protocol for off-cycle weight maintenance after stopping.
  • Long-term thyroid C-cell tumor risk in humans (boxed warning is rodent-data driven).
  • Whether the daily-dosing requirement gives any clinical advantage over weekly semaglutide.

Frequently Asked Questions

What is liraglutide?

Liraglutide is a once-daily GLP-1 receptor agonist sold as Victoza (1.2–1.8 mg, type 2 diabetes) and Saxenda (3.0 mg, chronic weight management). It was the first long-acting GLP-1 analog approved for obesity in 2014 and produced ~8% mean weight loss over 56 weeks in the SCALE Obesity trial.

How does liraglutide compare to semaglutide?

Same drug class, same mechanism. Semaglutide has a longer half-life (once-weekly vs once-daily) and produces nearly twice the weight loss in head-to-head data (~15% vs ~8% over 1+ year). Liraglutide remains useful when daily dosing is preferred, in adolescents, or when semaglutide is unavailable.

Why is liraglutide injected daily when semaglutide is weekly?

Liraglutide uses a C16 monoacyl fatty-acid modification that extends its half-life to ~13 hours via albumin binding. Semaglutide uses a C18 fatty diacid linker that pushes the half-life to ~7 days, enabling weekly dosing. The structural change came directly from learning what worked with liraglutide.

What are the side effects of liraglutide?

Most common: nausea, vomiting, diarrhea, constipation, and injection-site reactions — mostly mild-to-moderate and usually subside after dose escalation. Boxed warning for thyroid C-cell tumors based on rodent data; contraindicated with personal/family history of medullary thyroid carcinoma or MEN-2.

Is liraglutide still used in 2026?

Yes, but mostly as second-line. Most new GLP-1 prescriptions now go to semaglutide or tirzepatide for better efficacy and weekly dosing. Liraglutide retains use in pediatric obesity (12+), patients who prefer daily dosing, or where supply chain constraints favor older GLP-1s.

⚠️ Disclaimer

Educational purposes only. Not medical advice.

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