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The FDA approved an Eli Lilly request to market its type 2 diabetes medication tirzepatide (Mounjaro) as a weight loss drug. Antonio Diaz/Getty Images
  • Federal regulators have approved the drug Zepbound to treat obesity and weight-management issues.
  • The drug contains the active ingredient tirzepatide, which Eli Lilly uses in its drug Mounjaro that was approved last year as a treatment for type 2 diabetes.
  • Experts say the use of trizepatide as a weight-loss treatment is an important alternative, but they note that physicians should still closely monitor people who take the medication.

The Food and Drug Administration (FDA) has approved the use of a new weight loss drug sold by Eli Lilly & Co. under the brand name Zepbound.

Zepbound is an injectable drug that is being recommended for use in people who have obesity or who are overweight with at least one weight-related condition such as high blood pressure.

Regulators say it should be used along with a lower calorie diet and regular physical activity.

Zepbound contains tirzepatide, also in Eli Lilly’s diabetes drug Mounjaro. Tirzepatide has shown promise as a weight-loss treatment with one clinical trial reporting it reduced participants’ weight by as much as 22%.

The results were encouraging enough that FDA officials decided to fast-track the medication to be reviewed for treating obesity.

“Obesity and overweight are serious conditions that can be associated with some of the leading causes of death such as heart disease, stroke and diabetes,” said Dr. John Sharretts, the director of the Division of Diabetes, Lipid Disorders, and Obesity in the FDA’s Center for Drug Evaluation and Research, in a statement.

“In light of increasing rates of both obesity and overweight in the United States, today’s approval addresses an unmet medical need.”

Mounjaro was approved in 2022 as a weekly injectable, glucose-lowering treatment for type 2 diabetes (T2D).

Dr. Bubu Banini, an obesity medicine doctor and assistant professor of digestive diseases at the Yale School of Medicine in New Haven, Connecticut, told Healthline earlier this year that the dual use of trizepatide makes sense.

“With obesity being an underlying issue for most people with diabetes mellitus, those taking tirzepatide for diabetes tend to experience weight-loss benefits as well,” Banini said.

“The data so far for tirzepatide use for weight loss in those without diabetes appears very promising. Patients interested in taking tirzepatide should speak to their doctor prior to starting it.”

Eli Lilly officials said last year the company would use data from the original trial and from an ongoing trial to gauge the effectiveness of tirzepatide in people with type 2 diabetes who also have excess weight or are living with obesity.

The second trial was initially expected to be finished by April, though the FDA’s fast-track designation allowed for rolling submission of trial data. That meant the FDA could review data as it comes in instead of waiting for the trial’s conclusion.

The FDA grants fast-track designations for medications that can fill a serious unmet medical need.

Zepbound is given in six injectable doses. The product is expected to be available by the end of December at a list price of $1,059.

Dr. Heather Martin, the medical director of the primary care program at virtual health platform K Health, told Healthline in December 2022 that her platform imposed strict criteria in prescribing Mounjaro due to its rising popularity and concerns that there wasn’t enough.

“We have strict criteria to be eligible for prescribing Ozempic and other medications to manage your weight,” Martin said.

“Patients must have a BMI (body mass index) over 30, or a BMI over 27 with one associated condition like hypertension or type 2 diabetes and have been unable to lose and keep off weight with lifestyle changes alone.”

Banini told said the price seems to have leveled off and availability has increased.

“Tirzepatide currently costs between $900 and $1,100 for a 4-week supply,” Banini said “There were issues with availability in late 2022, which appears to have mostly resolved.”

The demand for tirzepatide will at least partially be driven by the ability of people without diabetes to use it.

Dr. Holly Lofton, an obesity medicine specialist at NYU’s Langone Health, told Healthline earlier this year there’s already evidence tirzepatide will be safe for both uses.

“Setting efficacy has been demonstrated in both patients with and without type two diabetes,” Lofton said. “It has been proven to be safe and effective for weight management and those with a BMI (body mass index) of 30 or BMI of 27 with the weight-related comorbidity.”

Lofton said for some people there can be drawbacks for taking the medication, which mimics a hormone that helps reduce appetite and food intake. It also may help the body break down fat and sugar.

“As with other GLP-1 (glucagon-like peptide) agonists, the medication is not recommended for those with the family or personal history of medullary thyroid carcinoma, or multiple endocrine neoplasia type two,” Lofton said

Banini told Healthline there are side effects from Mounjaro.

“The most common side effects are related to the gastrointestinal tract, including nausea, vomiting, diarrhea, or constipation,” Banini said. “Some people may experience redness or itching at the site of injection. People with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome type 2 (MEN2) should not take tirzepatide.”

Mounjaro isn’t the first diabetes drug to show promise for treating obesity.

Semaglutide, used in the drugs Ozempic and Wegovy, produced a nearly 16% reduction in body mass index in adults with obesity in a clinical trial.

Dr. Michael Glickman, a family and obesity medicine specialist who founded Revolution Medicine, Health & Fitness in Washington, D.C., told Healthline in December 2022 that Mounjaro is a “blockbuster drug” and “the most effective weight-loss treatment available on the planet, aside from bariatric surgery.”

“We are in a very exciting time right now in the obesity medicine field,” Glickman said. “The obesity epidemic began in the 1970s and for the first time in 50 years we now have several extremely effective treatment options to offer patients.”

Glickman said he was already seeing the results of the medications every day in people whose obesity is “reversing.”

“It will open the doors to treatment that millions of Americans have never had access to,” Glickman said.

According to the Centers for Disease Control and Prevention (CDC), the obesity prevalence rate in the United States increased from 30% in 2017 to nearly 42% in March 2020.

The estimated annual medical cost of obesity in the United States in 2019 dollars was nearly $173 billion.

The CDC says medical costs for adults with obesity were $1,861 higher than medical costs for people of healthy weight.

“Far too many hurdles continue to prevent people living with obesity from accessing obesity treatments that could lead to significant weight loss,” said Mike Mason, the executive vice president and president of Lilly Diabetes and Obesity, in a statement.

“Broader access to these medicines is critical, which is why Lilly is committed to working with healthcare, government and industry partners to ensure people who may benefit from Zepbound can access it.”

Martin emphasized one of the keys to treating type 2 diabetes is getting someone’s weight down.

“Being overweight is also associated with type 2 diabetes, hypertension, kidney disease, and more dire conditions,” Martin said. “Safely and sustainably managing your weight is an essential part of keeping you healthy for the long haul, making these medications important for those who meet the criteria.”

Martin said taking weight-loss medication can be part of a long-term strategy.

“Obesity is a chronic condition and is associated with many other chronic conditions that could be incredibly detrimental to your health,” Martin said. “We are lucky that medication now exists to help treat it, adding to the importance of accessibility for the patients who need it.”

Dr. Jonathan Fialkow, the chief of cardiology at the Baptist Health Miami Cardiac & Vascular Institute in Florida, said in December 2022 the benefits of Ozempic for weight loss made it harder to get these drugs because they were developed.

“Ozempic is not a weight-loss medication and was made to treat diabetes,” Fialkow told Healthline. “The high demand created for Ozempic for weight loss is limiting the supplies needed for diabetic patients. The pharmacies are out of it and we’re jumping through hoops to have them be able to continue on the medication.”

Fialkow also side effects, including nausea and other gastrointestinal complaints, aren’t insignificant.

“For people who may take it without proper management by a physician, they may lose significant weight and this may lower blood pressure,” Fialkow said. “They can then pass out and have other complications associated with that like hip fractures, skull fractures, and such. These medications need to be monitored by your doctor.”

Fialkow said there may be additional risks to prescribing these medications to people without diabetes.

“We want people to avoid the risk of losing weight and gaining an unnecessary harmful side effect,” Fialkow said. “Having said that, a major driver of weight gain/obesity, as well as a limitation of most diets, is hunger. People can be extremely overweight and crave food and feel hungry. This medication, through its mechanisms of action, creates a sense of satiety at lower levels of food intake.”

Fialkow said doctors have been struggling for decades to find an effective way to tackle overeating.

“To have a medication that, in a high-risk group, can achieve these multiple aims, is extraordinary,” he said.