My Dog’s Better Than Your Dog: Tirzepatide vs Semaglutide

Bragging rights. Yesterday, Lilly claimed them for its obesity medicine, the Zepbound brand of tirzepatide. The company announced topline results from a head-to-head trial of tirzepatide vs semaglutide for weight loss in persons with obesity or overweight and at least one obesity-related complication.

It should be no surprise that tirzepatide won this narrowly-defined contest. In a press release on results of the Surmount-5 open-label randomized trial, Lilly reported:

“On average, Zepbound led to a superior weight loss of 20.2% compared to 13.7% with Wegovy.i At 72 weeks, Zepbound beat Wegovy on both the primary endpoint and all five key secondary endpoints in this trial of adults living with obesity or overweight with at least one weight-related medical problem and without diabetes.

Note that all of the secondary endpoints were tied to weight. And it was clear from the pivotal trials for each of these drugs that the numbers for weight loss with tirzepatide were consistently higher than they were for semaglutide. If Lilly had not been confident of a win with this comparison, the company certainly would not have spent a hundred million dollars or more on this study.

Still, this counts as a win. Weight-related outcomes are important to persons living with obesity.

What About Health?

An obvious question, for now, remains unanswered: How do these drugs compare on health outcomes? It’s important because – as Lilly points out in its advertising – “health is not about what weight we lose.”

Currently, Novo Nordisk has the best claim on health outcomes, with definitive data showing semaglutide reduces the likelihood that persons with obesity and heart disease will have a stroke, a heart attack, or die if they take their drug. Lilly hopes to get such a claim, but the study to support that is still underway. Data on other important health outcomes are being collected in a wide range of studies. Over the next several years, we will have a lot to process on this subject

What Really Matters

We look forward to the full publication of these data on tirzepatide vs semaglutide.

But in the end, what really matters is finding medical care for obesity that improves life and health for each person it affects. Different people will have different responses to each of these drugs. Though weight outcomes are important, we would argue that longer term health outcomes are even more important. And those outcomes will vary from person to person.

Getting to the best possible health outcomes requires patience and careful follow-up over time.

Click here for Lilly’s statement on these new results, here, here, and here for further perspective.

Sawyer, photograph by Ted Kyle / ConscienHealth

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December 5, 2024