The people who took Zepbound, the Eli Lilly Obesity Medication, lost almost 50 % more weight than those who used Wegovy, of their rival Novo Nordisk, in the first comparative study of these successful medicines.
The clinical trial participants who took Tirzepatida, the drug marketed as Zepbound, lost an average of 22.8 kg (50 pounds) over 72 weeks, while those who took semaglutida, or wegovy, lost approximately 15 kg (33 pounds). This according to the study funded by Lilly, published on Sunday at the New England Journal of Medicine.
Both drugs are part of a new class of medications that act imitating intestinal and brain hormones that regulate appetite and feeling of satiety. However, the Tirzepatida acts on two of these hormones, known as LPG-1 and GIP, while the semaglutida acts only on the LPG-1, explained Dr. Louis Aronne, director of the Integral Weill Control Center of Weill Cornell Medicine.
“Two drugs together can produce better weight loss,” said Aronne, who directed the study and presented the findings on Sunday at the European Obesity Congress in Spain.
Although the tirzepatida imposed itself in what, according to Aronne, many consider a “career of efficiency”, both are important tools to treat obesity, which affects approximately 40% of American adults.
“The objective of these medications is to improve health,” he said. “Most people will not need the most effective medicine.”
The essay included 751 people from all over the United States overweight or obesity and at least another health problem related to weight, but not diabetes. Participants received weekly injections from the highest tolerated doses of Zepbound (10 or 15 milligrams) or Wegovy (1.7 or 2.4 milligrams).
At the end of the essay, who took Zepbound lost approximately 20 % of their body weight on average, compared to a loss of almost 14 % in those who took Wegovy. The Tirzepatida group reduced the circumference of its waist at approximately 17.8 centimeters (7 inches), compared to approximately 12.7 centimeters (5 inches) with semaglutida. In addition, almost 32 % of the people who took Zepbound lost at least a quarter of their body weight, compared to approximately 16 % of those who took Wegovy, according to the study.
Weight loss was 6 % lower in men than in women in both groups, the authors observed. As the participants of both groups lost more weight, they observed improvements in health indicators such as blood pressure, blood fat and blood sugar levels.
More than three quarters of the patients who took both drugs reported at least one side effect, mainly gastrointestinal problems from mild to moderate, such as nausea, constipation, diarrhea and vomiting. About 6% of the participants who took Zepbound left the essay due to adverse events, compared to 8% of those who took semaglutida.
The GLP-1 drugs have become increasingly popular, and at least 1 in 8 American adults reports its use, according to a survey conducted in 2024 by KFF, an independent organization in health policies. Zepbound generated 4.9 billion dollars in global sales last year. Wegovy raised almost 8.8 billion dollars (58.200 million Danish crowns).
Access and affordability have limited the generalized use of drugs. Tirzepatida and Semaglutida were recently eliminated from the list of shortage drugs by the United States Food and Medicines Administration (FDA). Both manufacturers recently launched programs that reduce costs to approximately $ 500 per month or less, depending on the dose.
Other factors can affect access. This week, CVS Health announced that Wegovy will become the preferred option in its standard form, or list of covered medications, starting July 1. Zepbound will be excluded.
It is important to have a range of medicines to treat a disease as widespread as obesity in the United States, said Dr. Angela Fitch, medical director of Knownwella company specialized in obesity care. It has been proven that Wegovy reduces the risk of serious heart problems by 20 %, he said. A medication can work well for a patient, but not for others.
“We are going to have to use them all, simply because we have many patients who need treatment,” he added.
