This treatment is in clinical trials and has not been approved by the FDA or any regulatory authority. It is not available for prescription. Current stage: Phase 3 ongoing. Estimated approval: 2027+ (estimated — not confirmed) — subject to change.
MariTide
Amgen · Code: AMG 133
MariTide takes a completely different approach to other weight loss drugs. While tirzepatide activates the GIP receptor, MariTide blocks it — using the opposite strategy — while also activating GLP-1. This antibody-peptide conjugate (a different drug class entirely from small molecules or peptide injections) only needs to be injected once a month or less, which could be transformative for adherence.
Quick read · 4 min
- •MariTide is an investigational drug — it has not yet been approved by any regulatory authority
- •Best trial result so far: up to 20% average weight loss
- •Current stage: Phase 3 ongoing
- •Expected approval: 2027+ (estimated — not confirmed) — this is an estimate and not confirmed
Based on clinical trials · No rankings · Every claim linked to source
Last reviewed: March 2026
How it works
MariTide is an antibody-peptide conjugate that simultaneously blocks GIP receptors (antagonist) and activates GLP-1 receptors (agonist). This is the opposite of tirzepatide, which activates GIP. Both approaches produce significant weight loss — suggesting GIP plays a complex role in appetite regulation that can be targeted in different ways. The monthly dosing is made possible by the antibody component, which has a much longer half-life than peptide drugs.
Phase 2 trial data by dose
In the Phase 2 trial (where people were randomly assigned to different doses or a dummy pill), participants on different doses lost the following amounts of weight. Phase 3 data is pending.
| Dose | At 24 weeks | At 48 weeks |
|---|---|---|
| –% | –% | |
| –% | –% |
Side effects (early-stage data)
Frequencies from Phase 2 trial data. Final Phase 3 safety profile may differ.
Notable findings
- ✓Monthly (or less frequent) dosing — potentially much better adherence than weekly injections
- ✓Works differently from all current approved drugs — a new mechanism class
- ✓~17% weight loss in participants with type 2 diabetes (Phase 2, 52 weeks)
- ✓Weight had not plateaued by 52 weeks in Phase 2 — suggesting potential for greater loss with longer treatment
How it differs from approved drugs
MariTide's defining difference is twofold: it's given monthly (not weekly), and it blocks the GIP receptor rather than activating it. All other approved and pipeline drugs that work on GIP (tirzepatide, retatrutide) activate GIP — MariTide blocks it. The fact that both approaches produce significant weight loss is scientifically surprising and suggests GIP is more complex than originally thought.
Community insights
These are personal experiences shared in public online communities — not medical advice.
“The monthly injection is the big draw here — a lot of people on Zepbound or Wegovy say weekly injections become routine, but monthly would be even easier to stick with long-term.”
Sources & references
- [1]Phase 2 randomised dose-finding studyAdults with obesity (with and without type 2 diabetes) · 52 weeksUp to ~20% weight loss (non-diabetic cohort) and ~17% (type 2 diabetes cohort) at 52 weeks. No weight plateau observed. Monthly dosing confirmed feasible.Nature Medicine / Amgen press release (2024) ↗