MariTide
Phase 3 program (MARITIME) under way; no approved dose.
An antibody that blocks the receptor, carrying two peptides that switch on . The draw is a dose once a month, possibly less often. Made by Amgen, also called Maridebart cafraglutide and AMG 133.
What the evidence shows
Side effects and risks
Who should avoid it: Anyone outside a clinical trial.
How it works
- Where it acts
- It blocks GIP receptors with an antibody, while its two attached peptides switch on GLP-1 receptors.
- What it changes
- Lower appetite. The antibody lasts for weeks, which is what allows a monthly dose.
- What people notice
- Up to about 20% weight loss over a year in phase 2. Nausea and vomiting, mostly after the first dose.
How it has been given in trials
Injection under the skin once a month. Eight-weekly and quarterly maintenance doses are being tested. There is no approved dose.
Getting it in the United States
The legal route for MariTide
Not approved. The only lawful way to get it is to join a clinical trial.
Company phase 3 trial enrolment
Not approved anywhere. The only reported route is joining a MARITIME trial, checked through the sponsor study website. Participants may get placebo, and phase 2 showed frequent early vomiting in some dosing groups.
Source: Amgen, 2025-06
Routes people use for any peptide in the United States
Telehealth prescribing
Online clinics prescribe after a questionnaire, sometimes with no live doctor visit, and mail the drug. FDA moved in February 2026 to restrict mass-marketed compounded copies and claims that they are generic equivalents.
Risk: Thin medical screening. Compounded versions are not reviewed by FDA for quality.
Covers: Approved GLP-1 drugs, compounded semaglutide and tirzepatide
Source: GZERO Media, Apr 2026
Clinical trial enrolment
The only lawful way to get an unapproved peptide drug with medical monitoring. ClinicalTrials.gov lists eligibility, sites and phone numbers. Researchers note recruitment is hard when people can buy the drug on the gray market instead of risking placebo.
Risk: Possible placebo assignment, strict eligibility and travel to a study site.
Covers: Investigational peptide drugs still in development
Source: NIH, finding a clinical trial
Routes people use for any peptide in the United States
Compounding pharmacy with prescription
A clinician prescribes and a pharmacy compounds. Twelve peptides left the FDA do-not-compound category in April 2026 and a panel backed six in July, but they are not yet formally eligible. Pharmaceutical-grade ingredient is scarce.
Risk: Legal status is unsettled until FDA rulemaking ends. Pharmacies may use research-grade ingredient.
Covers: BPC-157, TB-500, KPV, MOTS-c, Semax, Epitalon and similar
Source: Frier Levitt, Apr 2026
Med spas and weight-loss clinics
Very common. Secret shoppers called 75 clinics and med spas in two states after shortages ended. 92 percent offered compounded semaglutide and 87 percent tirzepatide, often mixed with B vitamins to look custom.
Risk: Four of 23 suppliers lacked sterile compounding licenses and four had disciplinary records.
Covers: Compounded semaglutide and tirzepatide
Source: American Med Spa Association on JAMA Health Forum study, Jul 2026
Concierge and longevity doctors
Cash-pay physicians build peptide plans for wealthy clients. Reporting from San Francisco says some source from overseas channels, domestic research-use-only sellers or the few compounding pharmacies that will supply clinicians.
Risk: A doctor's involvement does not guarantee a pharmaceutical-grade product.
Covers: BPC-157, thymosin alpha-1, Selank, Semax, CJC-1295, ipamorelin, retatrutide
Source: San Francisco Standard, Sep 2025
Cross-border purchase or import
FDA says importing drugs for personal use is illegal in most cases but it may not object to small personal quantities in limited situations. Reporting also describes people travelling to Mexico for injections.
Risk: Packages can be seized. Product origin and cold-chain handling are hard to check.
Covers: Approved prescription peptides sold abroad
Source: FDA, personal importation
Routes people use for any peptide in the United States
Research-chemical websites
Sites sell vials marked for research or not for human consumption, with no prescription. FDA says some ship direct to consumers with dosing directions, and it has sent warning letters. Retatrutide exists only through this route or trials.
Risk: Unknown identity, strength and sterility. No pharmacist or prescriber involved.
Covers: Retatrutide, semaglutide, tirzepatide, BPC-157 and most unapproved peptides
Source: FDA, unapproved GLP-1 drugs page
Direct orders from Chinese factories
Buyers message factory sales agents and pay by crypto or payment app. A minimum order of about ten vials pushes people to buy in bulk and share. A blockchain analysis found US buyers were the largest source of funds.
Risk: Many of the same vendors list fentanyl precursors. Lab reports sent by sellers cannot be verified.
Covers: GLP-1 copies, melanotan II, BPC-157, TB-500, GHK-Cu, epitalon
Source: TRM Labs, Oct 2026
Chat groups and social sellers
Dealers are found through Telegram, WhatsApp, Discord and influencer discount codes. In a May 2026 survey of 1,000 US users, 14.5 percent bought this way and three quarters asked an AI chatbot for dosing.
Risk: 45 percent of social media buyers in that survey reported an emergency or urgent care visit for a reaction.
Covers: Retatrutide and other research-use-only peptides
Source: The Ethos, May 2026
This describes what people do. It is not advice. The decision is yours.
More contextWhat public figures say, videos and articles and when options run out
What experts and influencers say
Paraphrased from the linked sources.
Warned that the stepped dose escalation planned for phase 3 may still not cut vomiting enough, after very high vomiting rates in some phase 2 groups.
Source: Fierce Biotech, 2025-06
Salim SyedWebsiteMixed view
Photo source: mizuhogroup.com
Said the phase 2 data and a low-dose starting study shaped the phase 3 design, and argued that monthly or less frequent dosing could help people stay on treatment.
Source: Fierce Biotech, 2025-06
Jay BradnerWebsiteRecommends
Money: Amgen executive
Photo source: learn.hms.harvard.edu
Raised concern that phase 1 data hinted at an effect on bone mineral density. Amgen shares fell. Amgen later said it saw no link between the drug and bone density changes.
Source: Clinical Trials Arena, 2024-11
Cantor FitzgeraldSourceWarns against
Said the stepped start should lower side effect rates but weakens the convenience argument for a long-acting injection.
Source: Fierce Biotech, 2025-06
Citi ResearchSourceMixed view
Presented second-year phase 2 findings at an investor conference: most participants kept their weight loss on lower monthly or quarterly dosing, with little nausea or vomiting reported.
Source: Finviz news, 2026-01
Robert BradwayWikipediaRecommends
Money: Amgen executive
Were not surprised by the second-year data and questioned which dose would support quarterly maintenance, since the high dose used is not in the current phase 3 trials.
Source: Finviz news, 2026-01
William BlairSourceMixed view
Watch and read
Explainers, reporting and podcasts worth your time. Summaries are ours. No sellers.
ADA 25: MariTide Treatment for Obesity in Patients with or without Type 2 Diabetes
Conference presentation of the phase 2 MariTide trial in adults with obesity, with and without type 2 diabetes, covering weight loss and tolerability.
Trial data straight from the scientific meeting.
Weight-Loss Drug MariTide Gains Momentum in Phase II Trial
Caitlin E. Cox, TCTMD reporter
Covers the published phase 2 results for once-monthly MariTide, including large weight loss, very common side effects, industry funding and the need for longer trials.
Pairs the headline results with the caveats.
Monthly GLP-1: How does MariTide Work?
Dr Rob Swanda, science educator
A science educator explains the design of MariTide, an antibody-based drug aiming for monthly dosing, and how it acts on gut hormone pathways.
Easy mechanism walk-through of a very new drug.
Amgen shares fall on anti-obesity drug | REUTERS
Short news clip on the drop in Amgen's share price after data on its experimental anti-obesity drug, showing how investors judged the results.
Quick reality check on how the market viewed the data.
When options run out
Uses people turn to when standard treatment has failed.
Quarterly maintenance after initial weight loss
- Who
- People who lose weight on the drug and want far fewer injections to hold the loss.
- Evidence
- Second year of a phase 2 trial, reported by the company at an investor conference. Not yet tested at this schedule in phase 3.
- Route
- MARITIME phase 3 programme
Source: Finviz news, 2026-01
Obesity with heart, kidney or sleep disease
- Who
- People with obesity plus heart failure, cardiovascular disease, kidney disease or obstructive sleep apnoea.
- Evidence
- No results yet. Amgen said it was exploring phase 3 studies in these groups and later reported six phase 3 studies under way.
- Route
- MARITIME phase 3 programme
Source: Amgen, 2025-06
Legal last-resort routes
Expanded access (compassionate use)
For a serious or life-threatening condition with no comparable alternative and no trial you can join. Your physician asks the company for the drug, then files with FDA and an ethics board. The company can refuse. Costs are often not insured.
Right to Try
For a life-threatening condition after approved options are exhausted and no trial is open to you. The drug must have finished Phase 1 and be in active development. Your doctor asks the manufacturer directly. FDA does not review requests.
Source: FDA, Right to Try
Trial finders
Search ClinicalTrials.gov by condition or drug name, check eligibility and call the listed site. ResearchMatch is a free NIH-funded registry that lets researchers find you. Discuss risks with your own clinician before enrolling.
Source: NIH, finding a clinical trial
Personal import for serious conditions
FDA may not object when a US citizen imports up to about three months of a drug for a serious condition with no effective US treatment, with written personal-use confirmation and a US doctor's details. It is discretion, not a right.
Source: FDA, personal importation
Patient-specific compounding
When the approved product cannot meet a specific need of an identified patient, a prescriber can order a compounded version from a licensed pharmacy. Lower price alone does not qualify. Ingredients must be pharmaceutical grade.
Questions people ask
How often is MariTide given?
Once a month as an injection under the skin in trials. Eight-weekly and quarterly maintenance doses are being tested.
How much weight loss did MariTide give?
Up to about 20% average loss at one year in phase 2. In the second year most people kept the loss on lower monthly or quarterly doses.
How does MariTide work?
It is an antibody that blocks the GIP receptor, carrying two attached peptides that switch on GLP-1 receptors. The antibody lasts for weeks, which allows a monthly dose.
What are the side effects of MariTide?
Nausea and vomiting, strongest after the first doses. Longer-term safety is not known.
Is MariTide approved?
No. The phase 3 program, MARITIME, is under way, and there is no approved dose.
Your notebook
Taking it? A ten-second daily check-in keeps a record of how you feel, to talk through with your clinician.
Sources
Structure: PubChem