MariTide
Also known as: Maridebart Cafraglutide
Amgen's monthly weight loss injection — and the only one in late-stage development you only have to take every four weeks rather than every week. Unusually, it activates GLP-1 but blocks GIP (most other dual drugs activate both). In Phase 2 it produced around 20% body weight loss at 52 weeks, with the added benefit of slow weight regain after stopping treatment in animal studies. Phase 3 MARITIME trials started in 2026. Generic name maridebart cafraglutide.
Dosage
Fixed dose: 140-420 mg subcutaneous monthly (titrated)
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Administration
Subcutaneous injection (once monthly)
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Effects
Weight Loss
Approximately 20% body weight loss at 52 weeks in Phase 2 with monthly dosing.
Monthly Dosing
Only late-stage obesity drug with once-monthly dosing — 21-day half-life via antibody conjugation.
Slow Weight Regain
Animal data suggests slower post-discontinuation regain than weekly GLP-1 agonists.
Novel Mechanism
GLP-1 agonist + GIP antagonist (opposite of tirzepatide which agonises both).
Mechanism of Action
MariTide (maridebart cafraglutide) is a peptide-antibody conjugate combining a GLP-1 receptor agonist peptide with a GIP receptor antagonist antibody. This dual GLP-1 agonist + GIP antagonist mechanism is distinctive — most competing dual incretin drugs (tirzepatide, CT-388, VK2735) activate both receptors. The rationale for GIP antagonism is based on genetic and pharmacological evidence that loss-of-function in GIP signalling is associated with reduced obesity, suggesting that blocking rather than activating GIP may produce superior weight-loss outcomes.
The GLP-1 agonist component drives the established appetite-suppression and glycemic-control effects of the incretin pathway. The GIP receptor antagonist antibody simultaneously blocks GIP signalling at adipocytes and centrally, which preclinical data suggest enhances energy expenditure, reduces lipid storage, and amplifies the weight-loss effect of GLP-1 receptor activation. Whether GIP agonism (as in tirzepatide) or GIP antagonism (as in MariTide) is superior remains an open question that Phase 3 head-to-head data may eventually resolve.
The antibody-conjugated structure produces an exceptional pharmacokinetic profile, with a half-life of approximately three weeks. This supports once-monthly subcutaneous dosing — a unique practical advantage over the once-weekly schedules of all other late-stage obesity drugs. Phase 2 results showed roughly 20% body weight loss at 52 weeks. Animal studies have also suggested slower weight regain after discontinuation than seen with shorter-acting GLP-1 agonists, possibly due to the prolonged drug exposure during the washout period. Phase 3 MARITIME trials launched in 2026 will define the molecule's clinical positioning.
Regulatory Status
Not yet FDA approved. Phase 3 MARITIME trials in obesity and type 2 diabetes began in 2026 (Amgen).
Risks & Safety
Common
nausea, vomiting (notably high incidence at first dose, requiring careful titration), diarrhea, decreased appetite.
Serious
pancreatitis, gallstones, possible muscle loss.
Rare
thyroid C-cell tumour class warning, severe allergic reactions. Monthly dosing means side-effect peaks are concentrated around injection time — different tolerability profile from weekly drugs.
Compare MariTide With
Research Papers
5Published: April 23, 2026
AI Summary
The Amgen discovery paper describing how AMG 133 (later named maridebart cafraglutide / MariTide) was designed by linking a GLP-1 peptide to a GIP receptor blocking antibody. Animal studies showed sustained weight loss with weekly dosing, supporting the move into human trials.
Published: February 1, 2026
AI Summary
A mouse study comparing the two opposing approaches to the GIP receptor used in tirzepatide (agonism) and MariTide (antagonism). Both lowered food intake and weight, but the antagonist worsened insulin sensitivity in this model, raising questions for long-term human use.
Published: September 4, 2025
AI Summary
The phase 2 trial in 592 adults showing once-monthly MariTide produced average weight loss of 12-16% at 52 weeks in people with obesity (8-12% in those who also had diabetes), compared with around 2% on placebo. Gastrointestinal side effects were common but eased with slower dose escalation.
Published: May 29, 2025
AI Summary
A review trying to make sense of why both blocking and activating the GIP receptor can help weight loss when paired with GLP-1 activation. It traces the evidence behind both tirzepatide and MariTide.
Published: November 1, 2024
AI Summary
A broad safety-focused review by Daniel Drucker discussing GLP-1 drugs including MariTide, with attention to muscle, bone, anesthesia and cancer-related concerns. A useful cautious counterweight to weight-loss-only headlines.
Frequently Asked Questions
What is MariTide?
Amgen's monthly weight loss injection — and the only one in late-stage development you only have to take every four weeks rather than every week. Unusually, it activates GLP-1 but blocks GIP (most other dual drugs activate both). In Phase 2 it produced around 20% body weight loss at 52 weeks, with the added benefit of slow weight regain after stopping treatment in animal studies. Phase 3 MARITIME trials started in 2026. Generic name maridebart cafraglutide.
What is MariTide used for?
Amgen's monthly weight loss injection — and the only one in late-stage development you only have to take every four weeks rather than every week. Unusually, it activates GLP-1 but blocks GIP (most other dual drugs activate both). In Phase 2 it produced around 20% body weight loss at 52 weeks, with the added benefit of slow weight regain after stopping treatment in animal studies. Phase 3 MARITIME trials started in 2026. Generic name maridebart cafraglutide.
What is the dosage for MariTide?
Phase 2 trials: 140-420 mg subcutaneous once monthly. Phase 3 MARITIME trials testing fixed-dose maintenance regimens after a stepwise escalation. Practical advantage of one injection every 4 weeks vs weekly for competitors.
What are the side effects of MariTide?
Common: nausea, vomiting (notably high incidence at first dose, requiring careful titration), diarrhea, decreased appetite. Serious: pancreatitis, gallstones, possible muscle loss. Rare: thyroid C-cell tumour class warning, severe allergic reactions. Monthly dosing means side-effect peaks are concentrated around injection time — different tolerability profile from weekly drugs.
How does MariTide work?
MariTide (maridebart cafraglutide) is a peptide-antibody conjugate combining a GLP-1 receptor agonist peptide with a GIP receptor antagonist antibody. This dual GLP-1 agonist + GIP antagonist mechanism is distinctive — most competing dual incretin drugs (tirzepatide, CT-388, VK2735) activate both receptors. The rationale for GIP antagonism is based on genetic and pharmacological evidence that loss-of-function in GIP signalling is associated with reduced obesity, suggesting that blocking rather than activating GIP may produce superior weight-loss outcomes. The GLP-1 agonist component drives the established appetite-suppression and glycemic-control effects of the incretin pathway. The GIP receptor antagonist antibody simultaneously blocks GIP signalling at adipocytes and centrally, which preclinical data suggest enhances energy expenditure, reduces lipid storage, and amplifies the weight-loss effect of GLP-1 receptor activation. Whether GIP agonism (as in tirzepatide) or GIP antagonism (as in MariTide) is superior remains an open question that Phase 3 head-to-head data may eventually resolve. The antibody-conjugated structure produces an exceptional pharmacokinetic profile, with a half-life of approximately three weeks. This supports once-monthly subcutaneous dosing — a unique practical advantage over the once-weekly schedules of all other late-stage obesity drugs. Phase 2 results showed roughly 20% body weight loss at 52 weeks. Animal studies have also suggested slower weight regain after discontinuation than seen with shorter-acting GLP-1 agonists, possibly due to the prolonged drug exposure during the washout period. Phase 3 MARITIME trials launched in 2026 will define the molecule's clinical positioning.
How is MariTide administered?
MariTide is administered via subcutaneous injection (once monthly).
What is the half-life of MariTide?
The half-life of MariTide is Approximately 21 days, supporting once-monthly dosing.
Is MariTide legal?
Not yet FDA approved. Phase 3 MARITIME trials in obesity and type 2 diabetes began in 2026 (Amgen).
Sources. This profile is built from peer-reviewed papers indexed on PubMed, FDA-approved labelling where available, and published clinical guidelines. The 5 primary sources used are listed in the Research Papers section above, each linked to its PubMed entry. See our editorial standards for how we research and review peptide profiles.
Last reviewed. by the Peptide Reference Editorial Team. Spot an error? Email a correction.
Not medical advice. Information on this page is for educational and research reference only. Many peptides covered are not approved for human use. See our full medical disclaimer.
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