MariTide (Maridebart Cafraglutide / AMG 133)

MariTide (AMG 133): UK Research & Regulatory Information

MariTide, also known as maridebart cafraglutide and AMG 133, is an investigational medicine being developed by Amgen for chronic weight management and related metabolic conditions.

MariTide is a differentiated antibody-peptide conjugate that activates the GLP-1 receptor while antagonising the GIP receptor. Its long-acting design is being studied with monthly or less frequent dosing. Amgen’s 2026 pipeline update states that Phase 3 MARITIME-1 and MARITIME-2 studies are ongoing.

MariTide is not currently an MHRA-authorised medicine for routine prescribing in the UK. It should therefore be presented as an investigational treatment under clinical development rather than as an approved weight-loss product available for ordinary purchase.

What Is MariTide?

MariTide is the development name for maridebart cafraglutide, formerly known as AMG 133. It is being investigated as a long-acting treatment for adults living with overweight or obesity, including people with and without type 2 diabetes.

The medicine uses an antibody-peptide conjugate structure intended to provide prolonged activity. This has allowed researchers to investigate dosing schedules that may require substantially fewer administrations than conventional weekly injectable weight-management medicines.

How Does MariTide Work?

MariTide has a distinctive mechanism involving two incretin-related pathways:

• GLP-1 receptor activation: GLP-1 signalling can affect appetite, food intake and glucose regulation.
• GIP receptor antagonism: MariTide blocks rather than activates the GIP receptor.

This differs from tirzepatide, which activates both GIP and GLP-1 receptors. It also differs from semaglutide, which primarily activates the GLP-1 receptor.

Because MariTide remains investigational, its eventual approved indications, dosing schedule, long-term safety profile and position in clinical practice cannot yet be assumed.

MariTide and Weight Management Research

MariTide has progressed from early clinical development into Phase 3 research for chronic weight management.

Amgen’s 2026 pipeline information identifies MARITIME-1 as a Phase 3 study in adults with overweight or obesity without type 2 diabetes and MARITIME-2 as a Phase 3 study involving adults with overweight or obesity and type 2 diabetes. Both programmes are ongoing.

Earlier Phase 2 research evaluated maridebart cafraglutide in adults with overweight or obesity, both with and without type 2 diabetes. ClinicalTrials.gov records the Phase 2 study as completed and identifies Amgen as the sponsor.

Researchers are continuing to evaluate the medicine to determine its longer-term effects, safety, tolerability and appropriate dosing.

How Often Could MariTide Be Given?

One of MariTide’s distinguishing features is its long-acting design.

Amgen states that MariTide is designed to support monthly dosing, with continued treatment potentially requiring as few as four or six doses per year depending on the development programme and dosing strategy. These schedules are investigational and should not be interpreted as an approved dosing recommendation.

Clinical trials have also investigated different subcutaneous presentations and dosing regimens. A 2026 Phase 1 study compared two subcutaneous presentations of maridebart cafraglutide.

MariTide and Type 2 Diabetes Research

MariTide is being studied in people with overweight or obesity who also have type 2 diabetes.

The MARITIME-2 Phase 3 programme is specifically evaluating chronic weight management in adults living with overweight or obesity and type 2 diabetes.

This research may help establish whether the medicine has a useful role across different metabolic populations. However, type 2 diabetes or weight-management use cannot be considered authorised in the UK solely because clinical trials are taking place.

MariTide and Cardiovascular Research

Amgen is also studying MariTide in cardiovascular outcomes.

The MARITIME-CV Phase 3 study is enrolling adults with established atherosclerotic cardiovascular disease and overweight or obesity. ClinicalTrials.gov identifies maridebart cafraglutide, AMG 133 and MariTide as names associated with the investigational treatment.

Cardiovascular-outcome research is important because obesity and metabolic disease are associated with cardiovascular risk. However, trial participation does not establish a cardiovascular indication for MariTide.

MariTide and Obstructive Sleep Apnoea Research

MariTide is also being investigated in adults with obesity and obstructive sleep apnoea.

ClinicalTrials.gov records Phase 3 studies evaluating maridebart cafraglutide in adults with obstructive sleep apnoea, including studies involving participants who are and are not using positive airway pressure therapy.

These studies are intended to determine whether weight reduction and the medicine’s metabolic effects may have clinical relevance in this population.

MariTide vs Semaglutide and Tirzepatide

Medicine	Mechanism	Current UK position
MariTide	GLP-1 receptor agonism + GIP receptor antagonism	Investigational
Semaglutide	GLP-1 receptor agonist	Authorised medicines exist for specific UK indications
Tirzepatide	GIP + GLP-1 receptor agonist	Authorised in the UK for specific indications

MariTide is therefore pharmacologically different from both semaglutide and tirzepatide. It should not be described simply as a stronger or newer version of either medicine.

For information about established medicines, see our Mounjaro (tirzepatide) and Ozempic (semaglutide) pages.

Is MariTide Approved in the UK?

MariTide is not currently authorised for routine prescribing in the UK.

The medicine remains in clinical development, with Phase 3 studies ongoing according to Amgen’s 2026 pipeline information.

Clinical-trial activity should not be confused with UK marketing authorisation. A medicine must receive the appropriate regulatory authorisation before it can be routinely marketed and prescribed in the UK.

Can You Buy MariTide Online?

MariTide should not be marketed as an approved UK weight-loss medicine or offered as a routine prescription product while it remains investigational.

Websites offering research-stage medicines outside legitimate clinical research arrangements may expose consumers to risks involving authenticity, quality, storage, contamination and incorrect dosing.

If you are looking for information about established treatment options, visit our weight-management medicines category or read our health and medicine articles.

Safety and Side Effects

The complete long-term safety profile of MariTide has not yet been established because clinical development is ongoing.

Clinical studies continue to assess adverse reactions, tolerability and the effects of different dosing regimens. Gastrointestinal effects are among the types of adverse events monitored during development of medicines affecting incretin pathways.

Patients should not assume that an investigational medicine has the same safety profile as an authorised GLP-1 medicine. Safety conclusions must be based on the complete clinical-development programme and future regulatory assessment.

Clinical Trials for MariTide

Several clinical studies have evaluated or are evaluating maridebart cafraglutide.

• Phase 2 obesity study: NCT05669599 evaluated dose response, efficacy, safety and tolerability in adults with overweight or obesity, with or without type 2 diabetes.
• MARITIME cardiovascular study: NCT07037433 evaluates MariTide in adults with atherosclerotic cardiovascular disease and overweight or obesity.
• Subcutaneous presentation study: NCT07313761 evaluated two subcutaneous presentations of maridebart cafraglutide.
• Liver-fat research: NCT07441252 evaluates MariTide in adults with elevated liver fat and overweight or obesity.

Frequently Asked Questions

What is MariTide?

MariTide is the development name for maridebart cafraglutide, also known as AMG 133. It is an investigational antibody-peptide conjugate being studied for chronic weight management and related metabolic conditions.

Is MariTide a GLP-1 medicine?

MariTide activates the GLP-1 receptor and antagonises the GIP receptor. Its mechanism is therefore different from medicines that activate both GLP-1 and GIP receptors.

Is MariTide the same as Mounjaro?

No. Mounjaro contains tirzepatide, which activates both GIP and GLP-1 receptors. MariTide is being investigated as a GLP-1 receptor agonist combined with GIP receptor antagonism.

Is MariTide the same as Ozempic?

No. Ozempic contains semaglutide, a GLP-1 receptor agonist. MariTide has a different molecular structure and mechanism involving GLP-1 activation and GIP receptor antagonism.

Is MariTide approved in the UK?

No. MariTide remains an investigational medicine and is not currently authorised for routine UK prescribing.

How often is MariTide taken?

MariTide is being developed as a long-acting subcutaneous treatment. Amgen reports that its design supports monthly dosing and potentially fewer administrations, but the final approved dosing schedule has not been established.

Can MariTide be prescribed by a UK doctor?

It should not be treated as a routinely prescribable UK medicine while it remains investigational. Access to investigational medicines is generally restricted to appropriate authorised clinical research arrangements.

Is MariTide available to buy online?

MariTide should not be marketed as an ordinary UK prescription product while it remains investigational. Products claiming to contain research-stage medicines may also present authenticity and safety concerns.

Who is developing MariTide?

MariTide is being developed by Amgen. The company identifies maridebart cafraglutide/AMG 133 as a major clinical-development programme in its 2026 pipeline updates.

Key Product Information

Product	MariTide (maridebart cafraglutide / AMG 133)
Developer	Amgen
Drug type	Antibody-peptide conjugate
Mechanism	GLP-1 receptor agonist + GIP receptor antagonist
Administration under investigation	Subcutaneous injection
Dosing concept under investigation	Monthly or less frequent administration
Primary research area	Chronic weight management
Additional research	Type 2 diabetes, cardiovascular outcomes, liver fat and obstructive sleep apnoea
UK authorisation	Not currently authorised for routine prescribing
Regulatory status	Investigational

Authoritative Resources

• Amgen – Q2 2026 MariTide pipeline update
• ClinicalTrials.gov – Phase 2 MariTide study
• ClinicalTrials.gov – MariTide cardiovascular study
• ClinicalTrials.gov – MariTide subcutaneous presentation study
• ClinicalTrials.gov – MariTide liver-fat study

Related Medicines and Information

For information about established medicines, see Mounjaro (tirzepatide), Ozempic (semaglutide) and Rybelsus (semaglutide).

You can also browse our weight-management category, diabetes category and health and medicine blog.

Important Disclaimer

This page is provided for educational and research information. MariTide (maridebart cafraglutide / AMG 133) is an investigational medicine and should not be presented as an MHRA-authorised treatment for routine UK prescribing. Clinical-trial and regulatory information can change as development progresses. Patients should speak with an appropriately qualified healthcare professional about authorised treatment options.