glp1versus

Byetta vs Zepbound

exenatide (GLP-1 receptor agonist) vs tirzepatide (Dual GIP and GLP-1 receptor agonist) — a complete side-by-side comparison.

AstraZenecaEli Lilly

Byetta weight loss

2.8%

Zepbound weight loss

22.5%

Byetta dosing

Twice daily (within 60 min before meals)

Zepbound dosing

Once weekly

Reviewed by Dr. Elena Vance, DOLast reviewed 14 sources cited

Quick Summary

Byetta (exenatide) and Zepbound (tirzepatide) are both incretin-based therapies. In clinical trials, Zepbound showed greater weight loss (22.5% vs 2.8%).

See the comparison table below for detailed side-by-side data.

Byetta vs Zepbound: Full Comparison

FeatureByetta(exenatide)Zepbound(tirzepatide)
Active Ingredientexenatidetirzepatide
Drug ClassGLP-1 receptor agonistDual GIP and GLP-1 receptor agonist
ManufacturerAstraZenecaEli Lilly
FDA Approved2005-04-282023-11-08
Approved Indications
  • Type 2 diabetes mellitus (adjunct to diet and exercise)
  • Chronic weight management in adults with BMI ≥30 or ≥27 with at least one weight-related comorbidity (adjunct to diet and exercise)
  • Treatment of moderate-to-severe obstructive sleep apnea in adults with obesity (December 20, 2024)
Routesubcutaneous injectionsubcutaneous injection
FrequencyTwice daily (within 60 min before meals)Once weekly
Starting Dose5 mcg twice daily2.5 mg weekly
Maintenance Dose10 mcg twice daily5 mg, 10 mg, or 15 mg weekly
Max Dose10 mcg twice daily15 mg weekly
Weight Loss (%)2.8%22.5%
A1C Reduction0.8%N/A (not indicated for diabetes)
Key TrialAC2993 Phase 3 (30 weeks)SURMOUNT-1 / SURMOUNT-5 (head-to-head vs semaglutide) (72 weeks)
List Price$800-$900/month$1,060-$1,176/month
With Insurance$25-$100/month (varies by plan)$25-$250/month (varies; weight-loss coverage is limited)
Savings CardLimited savings programs available$25/month (Lilly savings card, commercially insured)

Side Effects: Byetta vs Zepbound

Side EffectByettaZepbound
Nausea44%24-33%
Vomiting13%10-18%
Diarrhea13%18-25%
Headache9%Not reported
Dizziness9%Not reported
Dyspepsia6%7-10%
Jittery feeling4%Not reported
Pancreatitis (rare)<1%<1%
ConstipationNot reported13-17%
Abdominal painNot reported10-14%
Injection site reactionNot reported3-7%
Hair lossNot reported5-6%
Gallbladder eventsNot reported1.6%

Severity scale: 1 (mild) to 5 (serious). Based on FDA prescribing information and clinical trial data.

Related Comparisons

Byetta vs OzempicZepbound vs OzempicByetta vs WegovyZepbound vs WegovyByetta vs MounjaroZepbound vs MounjaroByetta vs RybelsusZepbound vs Rybelsus

Frequently Asked Questions

Sources & References

FDA & Regulatory

  1. Byetta FDA Drugs@FDA approval record — FDA
  2. Zepbound FDA Drugs@FDA approval record — FDA

Clinical Trial Records

  1. AC2993 Phase 3 clinical trial record — ClinicalTrials.gov
  2. SURMOUNT-1 / SURMOUNT-5 (head-to-head vs semaglutide) clinical trial record — ClinicalTrials.gov

Peer-Reviewed Literature

  1. DeFronzo RA et al. Effects of Exenatide on Glycemic Control and Weight Over 30 Weeks in Metformin-Treated Patients with Type 2 Diabetes. Diabetes Care 2005;28:1092-1100 — Diabetes Care
  2. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med 2022;387:205-216 — New England Journal of Medicine
  3. Malhotra A et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA). N Engl J Med 2024;391:1193-1205 — New England Journal of Medicine

Safety Communications

  1. FDA approves first medication for obstructive sleep apnea (Zepbound OSA indication, December 20, 2024) — FDA

Manufacturer Information

  1. Bydureon/Byetta patient website (AstraZeneca) — AstraZeneca
  2. Zepbound patient and healthcare provider website — Eli Lilly
  3. Lilly lowers price of Zepbound single-dose vials (December 1, 2025) — Eli Lilly Investor Relations
  4. SURMOUNT-5: Zepbound superior weight loss over Wegovy (May 11, 2025) — Eli Lilly Investor Relations

Reference Entries

  1. Exenatide entry on Wikipedia — Wikipedia
  2. Tirzepatide entry on Wikipedia — Wikipedia

This content is for informational purposes only and is not medical advice. Always consult your healthcare provider before making medication decisions. See our full medical disclaimer.