What is Zepbound® (tirzepatide)? Eli Lilly’s Newest Weight Loss Medication

Medically reviewed by: Kristin Baier, MD

The FDA recently greenlit a new weight-loss drug, Zepbound® (tirzepatide), sharing the same active ingredient as Mounjaro® (tirzepatide). Both drugs are manufactured by Eli Lilly & Co. and both are delivered as once-weekly injections. Learn more about Zepbound®, its availability, and why the news of its approval is so exciting. 

What is Zepbound® and how does it work? 

Like other well-known GLP-1 drugs—such as Wegovy®, made by competitor Novo Nordisk—Zepbound® is a once-weekly injectable medication that helps regulate blood sugar levels. It is meant to be used alongside lifestyle changes—i.e. changes to food, sleep, and exercise—to help adults with obesity or overweight lose weight. 

Zepbound® works similarly to the other drugs in the GLP-1 family, but it contains an extra molecule. It mimics the action of not one but two incretin hormones involved in blood sugar control: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). This unique dual action makes it the first FDA-approved weight loss medicine to act on both of these receptors.

Zepbound’s FDA approval on November 8, 2023, was based on data from the SURMOUNT-1 and SURMOUNT-2 trials.

SURMOUNT-1, involving 2,539 adults, unveiled Zepbound's effectiveness as an adjunct to diet and exercise, with study participants seeing substantial weight loss over 72 weeks. At the highest dose, participants shed an average of 48 lbs, compared to 7 lbs with a placebo. Notably, one in three individuals at the highest dose witnessed over 58 lbs (25% body weight) in weight loss, indicating the potential for remarkable progress in weight management.

While not directly treating these conditions, clinical trials also revealed positive changes in cholesterol, blood pressure, and waist size in individuals using Zepbound® for obesity or overweight with related medical issues.

What’s the difference between Zepbound® and Mounjaro®?

Zepbound®, FDA-approved for weight loss, shares its active ingredient (tirzepatide) with Mounjaro®, approved for type-2 diabetes. Despite different names and uses, both contain the same active ingredient and are packaged in the same dosages. 

What’s the difference between tirzepatide (like Zepbound®) and semaglutide (like Ozempic®)?

Semaglutide is available under multiple brand names: There’s Wegovy®, as well as Ozempic® and Rybelsus®. All three are manufactured by Danish pharmaceutical company Novo Nordisk. Ozempic® and Rybelsus® are indicated for type 2 diabetes, whereas Wegovy® is specifically indicated for the treatment of overweight and obesity. 

Tirzepatide, on the other hand, is recently available under two brand names: Mounjaro® and Zepbound®. Mounjaro® is indicated for the treatment of type 2 diabetes; Zepbound® is indicated for weight loss in those with obesity or overweight. Both are manufactured by Eli Lilly. 

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist (RA)—whereas tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist (RA). The latter works on an additional molecule, potentially giving tirzepatide a slight edge over semaglutide in efficacy. 

Zepbound® availability, dosage, cost, & side effects

Zepbound® is currently available to patients at pharmacies across the US. The medication will be available in six dosages mirroring Mounjaro's strengths, from 2.5 mg to 15 mg.

The drug is currently priced at $1,059.87 per fill as of 2024. Comparatively, Mounjaro® costs $1,023.04 per month, making Zepbound® marginally more expensive. Commercially insured individuals may obtain a one- or three-month prescription for as little as $25, subject to insurance coverage. 

Like other drugs in the GLP-1 family (GLP-1s and dual GIP/GLP-1s), clinical trials found that Zepbound® may cause mild gastrointestinal side effects. It’s also important to note that, like Mounjaro®, the drug’s label carries a Boxed Warning for the following scenarios:

• Do not use Zepbound® if you or any of your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC)
• Do not use Zepbound® if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
  

Is Zepbound® prescribed by Calibrate clinicians? 

Throughout the Calibrate program, our members make small, sustainable changes to help alter their set point, meet their weight loss goals, and improve their metabolic health. GLP-1 medication is just one piece of the puzzle—however, Calibrate does currently prescribe Zepbound® (tirzepatide) to members where clinically appropriate and insurance-eligible once the drug becomes available in pharmacies. 

Why Calibrate? 

Research shows that programs like ours can actually change your biology to reinforce metabolic changes, helping members lose 10% or more of their body weight—and keep it off. 

We're so confident in our program, we offer a Results Money Back Promise: you may qualify for a refund of your Membership Fees (minus a $250 fee for your initial clinical visit) if you do not achieve a minimum of 10% weight loss at the end of your Metabolic Reset Program.

Losing 10% of your body weight is clinically significant, as it lowers several risk factors for cardiovascular disease including high blood pressure, high cholesterol, and diabetes, while also reducing symptoms of depression, arthritis, and sleep apnea. 

Find out if you’re eligible today. 

Zepbound® for weight loss: Key takeaways

• Zepbound® stands out as the first FDA-approved weight loss medication to activate both GIP and GLP-1 hormone receptors. The drug’s efficacy was demonstrated in the recent SURMOUNT trials, with participants on the highest dose experiencing significant weight reductions compared to a placebo.
• While not an approved treatment for these conditions specifically, Zepbound® also showed positive impacts on cholesterol, blood pressure, and waist size in clinical trials.
• Gastrointestinal side effects and a Boxed Warning on thyroid C-cell tumors accompany Zepbound's use: As with all GLP-1-family medications, your Calibrate clinician will carefully review your medical and family history before prescribing Zepbound®.

Are you ready to make healthy and sustainable changes that will help you lose weight, improve your metabolic system, break the weight loss plateau cycle, and settle into a new, healthier set point for the long term? Learn more about Calibrate.