Zepbound vs Mounjaro: What’s the difference?

Zepbound and Mounjaro are both names for the drug tirzepatide. So what is the difference between the two?
Team Habitual
2/12/2024
5
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Checked by
2/12/2024
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Quick summary

Pharmaceutical company Eli Lilly hit the headlines early in November when they received approval for their latest weight loss drug—Zepbound. 

Zepbound joins the ranks of popular weight loss medications such as Wegovy, Ozempic, and Saxenda, as well as another drug manufactured by Eli Lilly—Mounjaro. Zepbound and Mounjaro are both brand names for the drug tirzepatide, which belongs to the GLP-1 class of medications. 

So what is the difference between Zepbound and Mounjaro? We break down everything you need to know about the two drugs and how you can choose between the two. 

A recap on tirzepatide

As previously mentioned, Zepbound and Mounjaro are both names for the drug tirzepatide. Tirzepatide is a type of GLP-1 agonist (otherwise known as GLP-1), like the drugs semaglutide and liraglutide, which have proven particularly popular as medication for helping you achieve weight loss. 

One key difference is that tirzepatide contains both GLP-1 and glucose-dependent insulinotropic polypeptide (GIP). Both of these have different effects which can help with management of blood sugar levels. 

GLP-1s and GIP mimic the effects of two gut hormones which are ordinarily released naturally after you have eaten. By mimicking these, they help release insulin to manage blood sugar levels, but also creates a feeling of fullness for longer. 

Tirzepatide is considered among the most effective of this class of medications, certainly compared to semaglutide. A 2023 study found that tirzepatide resulted in a weight loss of 17.8%, compared to 12.4% for semaglutide [1]. 

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Zepbound vs Mounjaro: What is the difference?

Zepbound and Mounjaro are practically considered the same drug. So in short, there aren’t really any key differences. Both come as a single-use injection pen, to be taken once a week. 

The main difference is in who they are prescribed for. Zepbound is designated for patients with obesity (with a BMI of 30+) or overweight (with a BMI of 27+) with weight related chronic health issues such as hypertension, dyslipidemia, or type 2 diabetes. Mounjaro, meanwhile, was initially designated for patients with type 2 diabetes, to help them lose weight in order to start to reverse some of the effects of the disease. 

That said, Mounjaro is more commonly prescribed off-label for patients looking to lose weight. In fact, it is widely considered that Zepbound has been developed to alleviate some of the supply challenges with Mounjaro. 

Dosage slightly varies between the two, with Zepbound allowing for a slightly stronger titration to have its full effect. With Mounjaro—you start at a 2.5mg concentration for weeks 1-4, then increase to 5mg for at least four weeks and as long as you stay on the drug. With Zepbound—you start with the same titration, but can increase at 2.5mg increments up to 15mg, which is the highest concentration. 

Neither Zepbound or Mounjaro are available yet in the UK—although with tirzepatide now approved by the UK regulators, both drugs are likely to start to hit the shelves in early 2024. It remains to be seen if either will become available via NHS prescription. 

References

[1] Azuri, J., Hammerman, A., Alboalhasan, E., et al (2023). Tirzepatide versus semaglutide for weight loss in patients with type 2 diabetes mellitus: A value for money analysis, Diabetes Obes Metab Apr 2023; 25(4):961-964. Accessible here

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