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What Is the New Weight Loss Drug Zepbound, and Why Has It Been Approved?

A measuring tape wrapped around a fork.
Credit: Diana Polekhina/ Unsplash
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The US Food and Drug Administration (FDA) has approved Zepbound™ (tirzepatide) for use in conjunction with a reduced-calorie diet and increased exercise to help obese adults manage their bodyweight.

The obesity “epidemic”

The World Health Organization has described obesity as an issue of “epidemic proportions”. In 2017, 4 million people died as a result of being obese. It’s a growing problem in both adults and children, with worldwide obesity tripling since 1975.

Being obese or overweight increases a person’s risk of diseases such as heart disease, stroke and diabetes, but research has shown that modest weight loss can prevent progression to type 2 diabetes, improve blood pressure and lower blood cholesterol.

The FDA announced it has granted fast-track approval of Zepbound™ specifically for adults with obesity (defined as a body mass index (BMI) of over 30 kg/m2 ) or overweight adults with at least one weight-related condition, including high blood pressure, type 2 diabetes or high cholesterol.

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It is administered once per week by injection and was shown to be effective for weight loss and management in two randomized, double-blind and placebo-controlled phase 3 trials.

John Sharetts, director of the Division of Diabetes, Lipid Disorders and Obesity at the FDA’s Center for Drug Evaluation and Research said, “In light of increasing rates of both obesity and overweight in the United States, today’s approval addresses an unmet medical need.”

How effective is Zepbound?

One of the trials looked at the efficacy of Zepbound™ in adults without diabetes, and the other studied adults with diabetes. Participants of both trials were either obese or overweight with a weight-related condition and received the drug or placebo alongside making changes to diet and physical activity.

In both trials, participants receiving either 5, 10 or 15 mg Zepbound saw a statistically significant reduction in bodyweight compared to those receiving the placebo.

In the trial that included people with diabetes, those taking the highest dosage of Zepbound lost 12% of their bodyweight on average. For those without diabetes, this figure was 18% when compared to  the placebo group.

Drug-based interventions are in high demand

In 2021, the FDA approved Wegovy™ (semaglutide) for weight management, the first drug to be approved for this purpose since 2014. The need for Wegovy is so high that the manufacturer, Novo Nordisk, reported that “demand continues to outpace our increasing production of Wegovy”.

How does Zepbound work?

Zepbound™ reduces appetite and food intake by activating receptors of glucagon-like peptide 1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP) hormones secreted by the intestine during digestion.

As well as reducing appetite, GLP-agonists like Zepbound™ can slow the emptying of the stomach so that it takes longer for the body to absorb nutrients, and help with blood sugar control by assisting the body to make more insulin. Tirzepatide, the active ingredient in Zepbound, has already been approved by the FDA for improving blood sugar levels in patients with type 2 diabetes.

Not the perfect solution

The trials illustrated that Zepbound™ can cause side effects including nausea, diarrhea, vomiting and fatigue. The FDA has noted that there are contraindications associated with taking Zepbound™, including patients with a family history of medullary thyroid cancer or those already taking a GLP-1 receptor agonist drug.

The drug is expected to be made available in the US by the end of 2024. 

This article is a rework of a press release issued by the FDA. Material has been edited for length and content.