MariTide
MariTide (Maridebart Cafraglutide)
Also called MariTide, maridebart cafraglutide, AMG 133
The monthly incretin
MariTide is Amgen's attempt at a once-a-month weight-loss injection instead of a weekly one. It is an antibody with two GLP-1 peptides stuck to it, which is why it lasts so long. In its Phase 2 trial people lost around 20% of their body weight. Not approved yet.
MariTide is Amgen's answer to a simple annoyance: nobody enjoys injecting themselves every week. It is built to last a month. To manage that, it is not really a peptide at all but an antibody with two small peptides attached, which is a much bigger, slower molecule that your body takes weeks to clear. In its Phase 2 trial people lost around 20% of their body weight on twelve injections a year. It is still in testing.
- Half-life
- Weeks rather than days, which is the whole point of the design
- Route
- One injection under the skin, once a month
- Typical dose
- Trials ran up to 420 mg monthly
- Availability
- Research-only
Human trials published, with more underway
What people use MariTide for
Reported uses, roughly in order of how often they are the reason someone goes looking. Whether it works for any of them is a separate question, answered under each one.
- Weight loss without a weekly injection
- The pitch is convenience. Twelve injections a year instead of fifty-two, for weight loss in roughly the same range as the weekly drugs.
- Weight that stays off after stopping
- Because it clears so slowly, weight regain after the last dose looked slower than usual in the trial. Interesting, but a Phase 2 observation rather than a settled fact.
Mechanism of Action
How MariTide works
The interesting thing here is the delivery, not the destination.
- What it does. The business end is the same as Wegovy: it copies GLP-1 to turn appetite down.
- Why it lasts a month. Those peptides are bolted onto an antibody, the same kind of large protein your immune system uses. Antibodies are built to hang around for weeks, so the appetite signal keeps running long after a normal injection would have washed out.
- The other half of the design. It also blocks a receptor called GIP rather than activating it, which is the opposite of what tirzepatide does. Two drugs doing opposite things to the same receptor and both producing weight loss is one of the genuinely odd puzzles in this field, and nobody has fully explained it.
- What that means for you. A month of coverage from one shot, but also a month of commitment. If a dose disagrees with you, waiting it out takes weeks rather than days.
MariTide dosage calculator
Opens at 420 mg, from the doses reported for MariTide. Change any box to match your own vial. It works out where to pull the plunger to.
How much is in the vial?
Printed on the label, in milligrams
How much water did you add?
Bacteriostatic water, in millilitres
What dose are you taking?
The dose you already intend to use
Which syringe?
Barrel size, printed on the wrapper
Draw to
Too much
That dose is 84 mL, more than a 0.5 mL syringe holds. Use a larger syringe, or add less water.
- Strength once mixed
- 5 mg/mL
- Doses in the vial
- Less than one
10 mg in 2 mL makes 5 mg/mL. A 420 mg dose is 84 mL of that, which is more than the barrel holds.
This is arithmetic, not advice. It converts a dose you already have into a mark on a syringe. It does not tell you what dose to take, and MariTide is not prescribed by us. Dosing belongs with a qualified clinician.
MariTide side effects: what people reported
Stomach upset again, but with a twist that comes from the monthly schedule: instead of a mild weekly wave, people describe a heavier few days after each shot.
What most people notice
- Nausea concentrated in the days right after an injection
- Vomiting
- Appetite falling away for most of the month
Worth keeping an eye on
- A rougher first week than weekly drugs, because the whole dose lands at once
- If a dose disagrees with you, it is a long wait for it to clear
Dose matters. Starting at a full dose rather than building up caused noticeably more of it, which is why later trial arms introduced a ramp.
Source: Phase 2 trial, New England Journal of Medicine, 2025. This is a summary of published findings, not a complete safety profile and not medical advice. MariTide should only be considered with a qualified clinician who knows your history.
Your Genetics & MariTide
The genes involved in how MariTide works
MariTide works through the receptors these genes build, and the genes vary from person to person. Researchers have linked some of that variation to differences in how people respond. A DNA report tells you which versions you carry.
GIPR · ••
The Glu354Gln (E354Q) variant is a reduced-function, lower-BMI-associated allele. It's mechanistically congruent with a GIP-antagonist drug — but honesty matters here: no human pharmacogenetic study yet shows an E354Q carrier responds better to a GIP antagonist than to a GIP agonist. Treat it as a hypothesis, not a prediction.
GIPR · ••
A second reduced-function GIPR allele in the same direction. It adds to the mechanistic plausibility of the antagonist class, with the same caveat that direct response data don't yet exist.
FTO · ••
FTO risk alleles raise appetite drive and set-point. As with all incretins, a higher genetic set-point is the case where a high-efficacy agent is most justified.
GLP1R · ••
Shapes the GLP-1-agonist arm of MariTide. Weak-signaling variants can blunt the agonist component independent of the GIP-antagonist effect.
The dots after each gene are where your own result goes. Your report fills them in with the two letters you carry at that position.
Which variants do you carry?
Upload your DNA data, or get tested through our partner, to find out.
Commonly combined with
What MariTide is most often paired with, and why:
Tesamorelin
Visceral Fat StackStrong EvidenceTesamorelin (GHRH Analog)
A stabilized growth-hormone-releasing-hormone (GHRH) analog and the only GH-axis peptide with an FDA approval (Egrifta, for visceral fat in HIV-associated lipodystrophy). It stimulates your own pulsatile GH release, which drives IGF-1 and preferential breakdown of visceral (deep belly) fat — backed by real randomized trial data on VAT reduction. Off-label use for visceral fat is common. WADA-banned in sport.
3
Gene variants
40+
Studies
Bimagrumab
Lean-Mass StackEmerging EvidenceBimagrumab (Anti-ActRII Monoclonal Antibody)
Every other drug on this list makes you eat less. Bimagrumab does something different: it takes the brakes off muscle. Your body runs a signal that stops muscle growing past a point, and this blocks it. The result in trials was unusual, people lost about a fifth of their body fat while actually gaining muscle, which is the opposite of what normally happens when you lose weight. It is given by drip in a clinic, not injected at home, and it is not approved.
3
Gene variants
15+
Studies
Sourcing & access
Where to buy MariTide
MariTide is sold as a research compound, not a licensed medicine, so quality and legal status vary widely by country and vendor. If you're sourcing it, treat independent purity testing as non-negotiable.
- Insist on a recent third-party Certificate of Analysis (COA) for the exact batch — labs like Janoshik verify purity and identity.
- Check the legal status where you live before ordering — it differs from country to country.
- Reconstitute correctly with bacteriostatic water and start at a conservative dose.
Before you buy: see whether your DNA actually responds to MariTide, and at what dose. Analyze my DNA — $99 →
Educational information only, not medical advice. Some outbound links are affiliate links (disclosed, at no extra cost to you). Most peptides are not FDA-approved — consult a qualified professional and check your local laws before purchasing.
Worth knowing before you consider MariTide
Interactions and situations where there is a specific reason to be careful. Where the honest answer is that nobody has studied something, it says so and says what that leaves open.
- Not available
- Phase 2 done, larger trials running. No prescription route exists.
- A monthly dose is hard to take back
- The convenience cuts both ways. With a weekly drug a bad reaction fades in days; here you are living with the dose for weeks.
Last updated
Frequently Asked Questions
What is MariTide?
MariTide (maridebart cafraglutide) is an investigational once-monthly weight-loss drug from Amgen. It combines GLP-1 receptor agonism with GIP receptor antagonism in an antibody-peptide conjugate, and its standout feature is monthly rather than weekly dosing.
Why does MariTide block GIP when tirzepatide activates it?
It's one of the genuine open questions in obesity pharmacology — both activating and blocking the GIP receptor appear to support weight loss through different mechanisms. MariTide bets on antagonism; tirzepatide on agonism. The Phase 3 data will help settle which wins for whom.
Is MariTide approved?
No. As of 2026 MariTide is investigational, in the Phase 3 MARITIME programme. It is not an available prescription.
Your next move
Two ways forward with MariTide.
Not sure it's for you?
How does MariTide relate to your genes?
Your report scores MariTide against your receptor, pharmacogene and pathway variants and shows the genetic markers relevant to it, with commonly cited dosing information to review with a clinician.
Analyze my DNA — $99