Metabolic Comparison

Maritide vs Tirzepatide

Comparison of Amgen's long-acting investigational GLP-1/GIP dual agonist maritide with FDA-approved tirzepatide for obesity and type 2 diabetes.

Last updated: January 28, 2026

Dossier labels summarize each dossier's research scope. They do not establish comparative treatment benefit or safety. Read the comparison below in that context.

MariTide

Dossier overview

Moderate Evidence
View full dossier

Tirzepatide

Dossier overview

High Evidence
View full dossier

Overview

Maritide (AMG 133) is Amgen’s investigational dual GLP-1/GIP receptor agonist being developed for obesity, while tirzepatide (Mounjaro, Zepbound) is an FDA-approved dual agonist from Eli Lilly for type 2 diabetes and obesity.

Key distinction: Tirzepatide is an approved medication with extensive clinical data; maritide is still in clinical development with promising but limited data.

Key Facts

AspectMaritide (AMG 133)Tirzepatide
DeveloperAmgenEli Lilly
ClassGLP-1 agonist / GIP antagonistGLP-1/GIP dual agonist
FDA StatusInvestigational (Phase 2)Approved (2022/2023)
Brand NamesN/AMounjaro, Zepbound

Mechanism Comparison

AspectMaritideTirzepatide
GLP-1 ReceptorAgonistAgonist
GIP ReceptorAntagonistAgonist
ApproachBlocks GIP while activating GLP-1Activates both receptors
Half-life~21+ days~5 days

How They Work

Maritide:

  • GLP-1 receptor agonist component stimulates insulin secretion and satiety
  • GIP receptor antagonist component blocks GIP action
  • Rationale: Some research suggests GIP antagonism may enhance weight loss
  • Long half-life allows monthly dosing
  • Bispecific antibody-peptide fusion technology

Tirzepatide:

  • Dual agonist at both GLP-1 and GIP receptors
  • GIP activation enhances GLP-1 effects on metabolism
  • Single peptide molecule with dual receptor activity
  • Weekly dosing maintains consistent drug levels

Evidence Quality

Maritide Research

Trial PhaseStatusKey Findings
Phase 1CompletedDemonstrated GLP-1 agonism + GIP antagonism
Phase 2 (Obesity)Ongoing/ReportedSignificant weight loss (up to ~15-17% reported)
Phase 3Not yet initiatedPending
Long-term dataNot available—

Current evidence:

  • Limited to Phase 1/2 data
  • Promising weight loss results in early trials
  • Monthly dosing demonstrated feasibility
  • Full safety profile not yet established

Tirzepatide Research

Trial PhaseStatusKey Findings
SURPASS (T2D)Completed1.5-2.4% A1c reduction
SURMOUNT (Obesity)Completed15-22% weight loss
Phase 3ExtensiveMultiple completed trials
Real-world dataGrowingPost-marketing experience

Established evidence:

  • Largest RCTs in obesity showed ~20%+ weight loss
  • Superior efficacy to semaglutide in head-to-head trials
  • Approved for both type 2 diabetes and chronic weight management
  • Well-characterized safety profile from large trials

Evidence Strength Comparison

FactorMaritideTirzepatide
Peer-reviewed studiesLimitedExtensive
Phase 3 trialsNone completedMultiple completed
Total patients studiedHundredsThousands
Long-term safetyUnknownEstablished (2+ years)
Overall qualityLow (early development)High

Efficacy Comparison

Weight Loss

MetricMaritideTirzepatide
Phase 2 weight loss~14-17% (reported)15-22%
Phase 3 weight lossPending15-22%
Maintenance dataNot availableAvailable
CertaintyLowHigh

Glycemic Control

MetricMaritideTirzepatide
A1c reductionLimited data1.5-2.4%
Diabetes indicationNot pursuedFDA approved
Data qualityEarlyRobust

Side Effects

Maritide (Limited Phase 2 Data)

Side EffectReportedNotes
NauseaYesCommon with GLP-1 class
VomitingYesCommon with GLP-1 class
DiarrheaYesGI effects expected
Injection site reactionsYes—

Tirzepatide (Established Profile)

Side EffectIncidenceManagement
Nausea12-33%Dose titration helps
Diarrhea12-21%Usually transient
Vomiting5-12%Dose-dependent
Constipation6-12%Common
Injection site reactions2-7%Mild, transient

Safety Considerations

Maritide:

  • Full safety profile unknown
  • Long-acting nature could prolong adverse effects
  • Monthly dosing may be advantage if well-tolerated
  • GIP antagonism effects long-term unknown

Tirzepatide:

  • GI side effects most common, usually improve with time
  • Rare pancreatitis risk (class warning)
  • Thyroid C-cell tumor warning (rodent findings)
  • Not for patients with MEN2 or medullary thyroid cancer history

Regulatory Status

AspectMaritideTirzepatide
FDA (T2D)Not approvedApproved (Mounjaro, 2022)
FDA (Obesity)Not approvedApproved (Zepbound, 2023)
EMANot approvedApproved
Development stagePhase 2Post-marketing
AvailabilityClinical trials onlyPrescription available

Cost Considerations

FactorMaritideTirzepatide
Current costN/A (investigational)~$1,000+/month retail
Insurance coverageN/AVariable, often limited
Projected costUnknown—

Who Might Consider Each

Tirzepatide May Be Appropriate For:

  • Type 2 diabetes requiring additional glycemic control
  • Chronic weight management with BMI criteria
  • Those who want established, approved treatment
  • Patients who can manage weekly injections

Maritide (If Approved) Could Be For:

  • Patients preferring less frequent injections
  • Those who have tried other GLP-1 agents
  • Obesity treatment (primary focus)
  • Must await regulatory approval

Summary

FactorMaritideTirzepatide
Evidence qualityLow (Phase 2)High (Phase 3, approved)
Efficacy (weight loss)Promising (~15-17%)Established (15-22%)
MechanismGLP-1 agonist / GIP antagonistGLP-1/GIP dual agonist
AvailabilityInvestigationalPrescription
Safety profileIncompleteWell-characterized

Key takeaway: Tirzepatide is an approved medication with extensive data supporting its use. Maritide shows promise with monthly dosing and a novel mechanism but remains investigational. Patients should only access maritide through clinical trials until approval.


This comparison is for educational purposes only. Maritide is not FDA-approved; tirzepatide requires a prescription. Consult a healthcare provider for treatment decisions.

Stay Updated on Peptide Comparisons

Get notified when we publish new comparison dossiers and evidence reviews.

No spam. Unsubscribe anytime.

Disclaimer: This comparison is for educational purposes only and does not constitute medical advice. Individual responses to medications vary. Always consult a qualified healthcare provider before making treatment decisions.