Zepbound, made by Eli Lilly, is the newest GLP-1 agonist medication approved by the FDA for weight loss. It contains tirzepatide, the same active ingredient in Mounjaro; this drug is unique in its mechanism of action, being the first and only treatment of its kind that activates both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) hormone receptors.
Here are six things to know about this in-demand medication before it hits pharmacy shelves.
1. When will Zepbound be available?
It’s expected to be available by the end of November, but Eli Lilly isn’t making any promises. Even once Zepbound technically becomes available, it might not be easy to get right away. High demand for the drug might make it challenging for manufacturers to meet market needs. (We’ve already seen this happen with the other brand-name GLP-1s.) Additionally, the issue of insurance coverage is a critical aspect to consider. New medications, especially those in specialized categories like weight management drugs, may not be immediately covered by insurance companies. This lack of immediate coverage can pose an additional barrier to access, especially for a drug like Zepbound that may be in high demand. It's advisable for individuals interested in Zepbound to check with their insurance providers to ascertain whether this medication will be covered and, if so, when that coverage might begin. This step is crucial as it helps in planning both financially and in terms of managing expectations regarding the availability of the medication for personal use.
2. What’s different about Zepbound, and how does it work?
Zepbound is a weekly injectable weight-loss drug that contains tirzepatide, the same active ingredient in Mounjaro. Zepbound and Mounjaro are essentially the same medication with different branding; furthermore they’re available in the same dosages. They have different names because Zepbound is approved by the FDA to manage weight loss while Mounjaro is approved for Type 2 diabetes. (The same goes for Wegovy and Ozempic, which both contain semaglutide but are approved to treat weight loss and diabetes, respectively.)
More often than not, tirzepatide is described as a GLP-1 drug (including in this article). This is almost correct: Tirzepatide is very similar to GLP-1s, but it’s technically a GLP-1/GIP dual agonist. While GLP-1 drugs mimic the effects of one appetite-regulating hormone, tirzepatide acts on two. This is a small but potentially important difference, as tirzepatide has shown to be even more effective in clinical trials than true GLP-1s. Over 72 weeks, trial participants taking the maximum recommended dose of tirzepatide lost 18% of their body weight, on average. By comparison, the average weight loss in trials for semaglutide was 15% over two years, and 4-6% over 68 weeks for liraglutide.
As with all GLP-1s, tirzepatide is intended to be combined with a reduced-calorie diet and exercise for optimal effects.
3. Who’s Zepbound for?
Zepbound is approved for 1) people who have obesity, defined as a body mass index (BMI) of 30 or higher, and 2) people who have a BMI of 27 or higher and also have weight-related comorbidities, such as hypertension. The other two GLP-1 drugs approved for weight loss, Wegovy and Saxenda, have the same qualifications.
4. Could I just take Mounjaro for weight loss instead?
Maybe, but it would cost a lot. The FDA approved Mounjaro for Type 2 diabetes in May 2022. There’s been steady demand to use it off-label for weight loss, but insurance plans are unlikely to cover brand-name drugs for off-label use when other FDA-approved options are available. Without coverage, Mounjaro costs $1,000 per month or more. Zepbound’s approval won’t affect how insurers cover Mounjaro.
The impending arrival of a tirzepatide medication that’s specifically approved for weight loss is big news because more people will be able to afford to take it.
5. So, Zepbound will be covered by my insurance? How much will it cost?
Zepbound will be eligible for coverage for people who meet the diagnostic criteria (having obesity or being overweight and also having a related health condition). But coverage policies will likely vary by plan. Many commercial plans already cover Wegovy and/or Saxenda, and coverage for Zepbound should be similar. Government insurance plans do not currently cover GLP-1s for weight loss.
If your plan covers Zepbound, the price might be as low as a monthly $25 copay, according to Eli Lilly, the drug manufacturer. If you have commercial insurance that does not cover Zepbound, the price might be as low as $500 per month. That’s certainly not cheap, but it’s about half the list price for the drug, which is $1,059.
6. What are Zepbound’s side effects?
In clinical trials, the reported side effects of tirzapetide were similar to those for all GLP-1s. The most common was nausea, followed by other gastrointestinal issues — diarrhea, vomiting, constipation and acid reflux. The FDA approval also mentions burping and hair loss, which have been anecdotally reported for other GLP-1s too. There are more serious side effects and adverse reactions, but they’re rare. You can see the full list in the medication guide, which also has info on contraindications.