Tirzepatide: A novel obesity drug ushers in a new era of weight loss — because this one works

A new weight-loss drug is get a quick review by the FDAand some financial analysts predict it could break records, with up to $48 billion in annual sales. According to a recent clinical study, patients who received a high dose of the drug tirzepatide lost up to 21% of their body weight (an average of 52 pounds or 23.6 kg), more than any other weight-loss drug. Curiously, tirzepatide was not designed to treat obesity; in fact, it mimics a hormone traditionally thought to be responsible for weight gain.

The obesity epidemic

Fat cells (adipocytes) secrete hormones that regulate metabolism, affect satiety and trigger inflammation. Obesity develops when these cells accumulate more lipids than they can handle, which causes them to malfunction. Overloaded fat cells release molecules that can cause a cascade of metabolic and inflammatory problems that increase the risk of other serious conditions and diseases such as diabetes, hypertension, cardiovascular disease, cancer, asthma, and heart disease. hypercholesterolemia.

To alleviate stress on lipid-laden cells (and thus repair metabolic and inflammatory dysfunctions), obese people often need to reduce their body weight by at least 5-10%. The traditional intervention to achieve this reduction is lifestyle modification (eg, better diet and more exercise). However, these changes do not work for everyone. Even if they do work, they rarely act quickly, and when it comes to metabolic and inflammatory dysfunction, the sooner it’s fixed, the better.

Tirzepatide: a diabetes drug that causes weight loss

A handful of drugs can reduce body weight by 5-10%, but like lifestyle changes, they don’t work for everyone. For example, orlistat, approved in 1999, only works in about half of patients. However, this trend has changed in recent years. Semaglutideapproved in 2021, helped 86% of patients lose at least 5% of their body weight, with average weight loss of 15% (compared to 2.4% for the placebo). Since its approval, semaglutide (sold under the brand name Wegovy) has been hailed as a “transformative breakthroughin the fight against obesity. However, the new drug, tirzepatideleft semaglutide in its shadow: 91% of patients saw a reduction of at least 5%, with an average weight loss of 21% for the highest dose (compared to 3.1% for the placebo).

Surprisingly, tirzepatide was not originally designed to treat obesity. It is also the first drug to mimic a pair of hormones secreted by the gut that stimulate insulin production after a meal: glycogen-like protein-1 (GLP-1) and the glucose-dependent insulinotropic polypeptide ( GIP). Because both molecules stimulate insulin (which encourages cells in the body to take up glucose, causing blood sugar levels to drop), the researchers suspected that tirzepatide would make a good treatment for type 2 diabetes, and those assumptions were correct. .

Clinical trials revealed that the dual-targeting drug helped about 50% of patients achieve long-term glycemic control. However, these trials also revealed a big surprise: Tirzepatide provides weight loss that surpasses leading weight loss drugs. In other words, it would seem that tirzepatide effectively treats two of the most common diseases in the world: obesity and diabetes. This was a bit surprising, given that GIP was considered “obesity hormone.”

Tirzepatide acts as a new synthetic hormone

Of the two hormones that tirzepatide mimics, GLP-1 is by far the more well studied. It is a powerful tool for weight loss as it reduces appetite and food intake. it is a powerful tool in the management of diabetes because it stimulates the production of insulin. Some popular weight-loss drugs (like semaglutide) and diet drugs share structures with GLP-1 and stimulate the GLP-1 receptor.

GIP, on the other hand, is a bit of a mystery. Although discovered a decade before GLP-1, tirzepatide is the first drug to exploit its therapeutic potential. While GLP-1 inhibits appetite and food intake, GIP has no such effects. On the contrary, many studies suggest that GIP promotes obesity, earning it the nickname “obesity hormone.” For example, humans with genetic abnormalities in the GIP receptor are more likely to have lean body mass. Therefore, scientists generally believed that blocking the GIP receptor would induce weight loss; however, tirzepatide stimulates the GIP receptor.

Not surprisingly, scientists don’t fully understand the remarkable weight loss results of tirzepatide. A theory is that tirzepatide acts as a new synthetic hormone that triggers cellular processes that are slightly different from those of the natural hormones it was designed to mimic. Intestinal cells secrete GLP-1 and GIP as two separate molecules that can interact with their respective receptors independently of each other. Tirzepatide, on the other hand, is a single molecule that binds both receptors. Additionally, the tirzepatide molecule has special regions that allow it to remain stable longer than naturally produced hormones. These structural alterations can cause the dual action drug to act differently than the two naturally occurring hormones independently.

But Eli Lilly, the maker of tirzepatide, doesn’t need to understand exactly why the drug works to market it. The company plans to seek approval for the drug in April 2023.

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