What Is Zepbound Made Of? A Guide to Zepbound’s Ingredients and How It’s Made

Tirzepatide is the primary ingredient in Zepbound, an injectable medication for weight loss and obstructive sleep apnea. But tirzepatide isn’t its only ingredient. Several others help keep Zepbound stable and working the way it’s supposed to.

What are Zepbound’s ingredients? And how is it made?

What is the active ingredient in Zepbound?

Tirzepatide is the active ingredient in Zepbound. Once injected, it acts like two natural gut hormones:

• Glucose-dependent insulinotropic polypeptide (GIP)

• Glucagon-like peptide-1 (GLP-1)

Tirzepatide works in certain areas of your brain that help regulate appetite and food cravings. It also slows the movement of food through your digestive tract, helping you feel full faster and for longer. And it might counteract certain hunger hormones that play a role in weight gain.

Beyond this, tirzepatide also tells your pancreas to release more insulin after you eat. And it signals your liver to make less new glucose (sugar). This is why tirzepatide is also approved to treat Type 2 diabetes under the brand name Mounjaro.

What other ingredients make up Zepbound?

Zepbound has only one active ingredient (tirzepatide). But it has several inactive ingredients. These substances don’t affect how tirzepatide works in the body. They generally help maintain Zepbound’s shelf life and stability. They also help reduce pain during injection.

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Zepbound contains the following inactive ingredients:

• Sodium chloride (makes injections less painful)

• Sodium phosphate dibasic heptahydrate (buffer to keep Zepbound stable)

• Water for injection (carries tirzepatide into your body)

• Hydrochloric acid (adjusts acidity)

• Sodium hydroxide (adjusts acidity)

Do Zepbound vials have different ingredients from Zepbound pens?

No. Zepbound vials and Zepbound pens have the same active and inactive ingredients.

Keep in mind, Zepbound and compounded tirzepatide are not the same. Compounded versions may vary in the amount of tirzepatide and the type of inactive ingredients they contain. So it’s likely that there are differences between compounded tirzepatide vials and Zepbound vials or pens.

Does Zepbound contain preservatives?

No. Zepbound doesn’t contain preservatives. This is why the pens and vials are single-use only. So don’t try to split Zepbound doses or save leftover liquid inside vials for later.

Do Zepbound and Mounjaro have the same ingredients?

Yes. Zepbound and Mounjaro both contain tirzepatide as their active ingredient. What’s more, they contain the same inactive ingredients. And they offer the same range of doses in both a pen and vial.

EXPERT PICKS: WHAT TO READ NEXT

• How does Zepbound work? Pharmacists explain the science behind how Zepbound’s active ingredient, tirzepatide, works.

• Possible side effects: Learn about Zepbound side effects — from diarrhea to hair loss — and how to manage them.

• Cost considerations: Find out how much Zepbound costs (with and without insurance), plus ways you can save.

Zepbound and Mounjaro vary in their approved uses. They also have different recommended maintenance doses for each condition they treat.

Can any ingredients in Zepbound cause an allergic reaction?

Yes. It’s possible to have an allergic reaction to any of Zepbound’s active or inactive ingredients. This is very rare. But allergic reactions can be serious or even life-threatening. If you have allergies, make sure to review these with your prescriber and pharmacist before starting Zepbound.

If you experience allergic reactions, such as hives or a rash, contact your prescriber right away. If you have any symptoms that seem severe, such as trouble breathing, call 911 or go to the ER.

How is Zepbound made?

Zepbound is made using a process called hybrid solid-phase peptide synthesis/liquid-phase peptide synthesis (SPPS/LPPS). This process takes amino acids (protein building blocks) and puts them in a certain order to form tirzepatide. Once formed, scientists purify and freeze dry tirzepatide to create the final version that’s placed into Zepbound pens and vials.

Natural GIP and GLP-1 hormones only last for a few minutes in your body before it’s broken down. But the SPPS/LPPS process produces tirzepatide, a molecule that’s designed to resist rapid breakdown, keeping it active for much longer. This is why you have to inject Zepbound only once a week.

How to save on Zepbound

There are ways to save on Zepbound, which is available as a brand-name medication. If you have commercial insurance, you may be eligible to pay as little as $25 for a 1- or 3-month supply of Zepbound pens through the manufacturer’s copay savings program. If your plan doesn’t cover Zepbound, you may be able to pay $650 for a 30-day supply with the copay card.

Subscribers to GoodRx for Weight Loss can also access FDA-approved, brand-name GLP-1 medications like Zepbound. Lower-cost single-dose vials are also available through LillyDirect for $299 (2.5 mg), $399 (5 mg), and $449 (7.5 mg, 10 mg, 12.5 mg, and 15 mg) per month.

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Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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