Maridebart cafraglutide vs tirzepatide: how do these two medicines compare?

What is maridebart cafraglutide, and how does it differ from tirzepatide mechanically?

Tirzepatide acts on two gut-hormone receptors simultaneously — GIP and GLP-1. That dual activation slows gastric emptying, reduces appetite and influences how the body handles blood glucose. It is the only dual-agonist weight-loss medicine currently licensed in the UK, approved by the MHRA and recommended by NICE (TA1026, published December 2024) for adults with a BMI of 35 or above and at least one weight-related condition.

Maridebart cafraglutide takes a broader approach. It is a triple hormone receptor agonist, targeting GLP-1, GIP and glucagon receptors in a single molecule. In theory, activating the glucagon pathway adds a further lever on energy expenditure beyond what the dual mechanism in tirzepatide achieves. Whether that theoretical advantage translates into meaningfully superior real-world outcomes remains the central question the ongoing phase 3 trials are trying to answer. At the time of writing, maridebart cafraglutide has no MHRA licence for weight management in the UK.

It is worth pausing on that distinction. Tirzepatide has already completed large-scale phase 3 trials, with results published in the New England Journal of Medicine (SURMOUNT-1), and those results underpinned its UK regulatory approval. Maridebart cafraglutide is promising, but promising is not the same as approved.

What does the available evidence show about weight loss with each medicine?

For tirzepatide, the SURMOUNT-1 trial (2,539 adults with obesity, 72 weeks) reported average body-weight reductions of around 20–21% at the 15mg maintenance dose. The SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, found tirzepatide produced greater average weight loss than semaglutide 2.4mg over 72 weeks, the most directly comparable licensed alternative. Those figures come from large, peer-reviewed, phase 3 data.

Early phase 2 data for maridebart cafraglutide (from Amgen's MARITIME study programme) showed weight reductions of roughly 15–19% at varying doses over 52 weeks, which is competitive but comes from a smaller trial population than SURMOUNT-1. Phase 3 results are not yet available. This comparison table summarises where each medicine stands right now:

Comparing phase 2 data from one medicine against phase 3 data from another is not straightforward. Trial designs, populations and follow-up periods differ. The gap may narrow, widen or reverse when maridebart cafraglutide's phase 3 results land.

Can someone in the UK get maridebart cafraglutide today?

No. Maridebart cafraglutide is not licensed by the MHRA, cannot be prescribed through legitimate UK channels for weight management, and is not available at any GPhC-registered pharmacy, including ours. Any seller offering it as a ready-to-purchase weight-loss injection is not operating within the licensed UK supply chain. The MHRA's Yellow Card scheme exists to report suspect sellers, a quick check of any online pharmacy against the GPhC register takes under a minute and is the single most useful habit for anyone buying medicines online.

Tirzepatide, by contrast, is available now via a private prescription from a registered prescriber. Eligibility under the SmPC covers adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. For those who meet the NICE criteria, there is also a phased NHS rollout, though access depends on location and qualifying conditions. Our treatment overview explains both routes clearly.

People curious about how tirzepatide stacks up against other currently available medicines (rather than pipeline candidates) may find our tirzepatide versus liraglutide comparison or the dulaglutide versus tirzepatide page more immediately useful.

Which medicine should you consider, and how is that decision made?

Right now, the practical answer is simple: only one of these medicines can legally be prescribed in the UK for weight management. When maridebart cafraglutide does complete its phase 3 programme and potentially seek MHRA approval, the comparison will gain real clinical depth. Until then, a conversation about treatment options is a conversation about tirzepatide, Wegovy and the other currently licensed choices, and if you are wondering whether liraglutide is better than tirzepatide, that question has its own dedicated page worth reading before you decide.

Choosing between tirzepatide and any other licensed medicine involves factors a checklist cannot weigh: existing health conditions, what you've tried before, how you respond to GI side effects, and what your prescriber concludes after reviewing your full medical picture. A page like this one can lay out the facts; it cannot replace that review.

Our clinical team reviews every consultation personally. There is no algorithm reading your answers and issuing a prescription. If you want to explore whether tirzepatide is right for you, or to ask questions about how the emerging pipeline medicines differ, the right next step is a consultation. You can also read about how tirzepatide compares to semaglutide's injectable form on our maritide versus tirzepatide page, or explore Mounjaro pricing to understand the cost context before you start.

Which medicine suits you is a clinical decision our prescribers make with you.