Tirzepatide (Mounjaro): Here’s how the combination GLP-1 and GIP receptor agonist works — and how it compares with other GLP-1 RAs
Key Takeaways:
Tirzepatide has a unique ability to mimic the actions of two different types of hormones: GLP-1s and GIPs.
Wegovy and Ozempic as semaglutide medications activate the GLP-1 receptor, while Mounjaro as a tirzepatide activates two receptors: GLP-1 and GIP.
This approach seems to cause people who use tirzepatide (Mounjaro) injections to lose even more weight than those who use a single-agonist medication such as semaglutide.
It is important to note that these are regulated prescription weight loss medications and have significant side effects if used incorrectly.
Therefore, you must consult with a qualified specialist who can determine if these weight loss medications are right for you.
Mounjaro is expected to be available in Singapore in late 2024. You may discuss some alternative medications with your healthcare provider.
Certain glucagon-like peptide-1 receptor agonists (or GLP-1 receptor agonists, or simply GLP-1 RAs) have been gaining attention for their ability to control blood sugar and aid in weight loss. GLP-1 RAs can help to achieve good blood sugar control in people with diabetes – and these medications can also lead to weight loss.
Read more about GLP-1 RAs such as liragultide and semaglutide.
Another drug that has been approved by the U.S. Food and Drug Administration (FDA), and approved for use in Singapore, is tirzepatide (sold under the brand name Mounjaro). Mounjaro is currently approved by the Health Sciences Authority and the FDA for treating type 2 diabetes.
Are Mounjaro, Ozempic and Wegovy the same weight loss medications?
No, they are not the same weight loss medications. Both Ozempic and Wegovy are brand names for a drug called semaglutide. Meanwhile Mounjaro is the brand name for tirzepatide. The drugs work in similar ways to reduce appetite, but there are some differences in how they work.
How does tirzepatide work for blood sugar control?
Tirzepatide is a natural compound found in the body that helps perform several important bodily functions. It mimics GLP-1s. In addition, it mimics the effect of another class of hormones called glucose-dependent insulinotropic polypeptide (GIP). Tirzepatide’s ability to mimic two different types of hormones is unique.
GLP-1RAs mimic a natural hormone called glucagon-like peptide 1 (GLP-1). GLP-1s help regulate digestion and appetite. GLP-1RAs:
Slow down emptying of the stomach after a meal, helping you to feel full for longer.
Reduce cravings and emotional eating.
Stimulate the pancreas to secrete insulin.
Block the release of sugar from the liver.
Meanwhile, GIP hormones:
Stimulate insulin secretion
Improve insulin sensitivity
Aids GLP-1 hormones in their digestive and metabolic action by helping enhance its action of regulating appetite.
Tirzepatide, therefore, is a completely new drug class. Instead of being a single-receptor agonist, which semaglutide (Ozempic and Wegovy) is, tirzepatide (Mounjaro) activates two receptors at the same time – GLP-1 and GIP. Therefore, Wegovy and Ozempic as semaglutide medications activate the GLP-1 receptor, while Mounjaro as a tirzepatide activates two receptors: GLP-1 and GIP.
A new study by an international group of researchers, in collaboration with scientists from Eli Lilly (the maker of Mounjaro) and Novo Nordisk (the manufacturer of Ozempic and Wegovy), tried to examine how tirzepatide produces its effects on blood sugar and weight. The researchers found that tirzepatide triggers a strong GIP response instead of merely activating GLP-1 receptors in the body. This means that targeting both would lead to an additive effect. This approach also seems to cause people who use Mounjaro injections to lose even more weight than those who use a single-agonist medication such as semaglutide.
Clinical trials that have evaluated tirzepatide for the treatment of type 2 diabetes have demonstrated improvement in HbA1c, and fasting plasma glucose in patients with type 2 diabetes when used alone or in addition to metformin, SGLT2i and/or basal insulin.
In addition, study showed that in a 72-week trial, tirzepatide (10 mg and 15 mg) achieved up to 15.7% weight loss in adults with obesity, or overweight and type 2 diabetes.
Table 1. A comparison of the average weight loss of patients taking Saxenda (injectable), Wegovy (injectable), Wegovy (oral), and Mounjaro (injectable)
| Weight Loss* | |
|---|---|
| Saxenda (liraglutide) once a day injection | 5-10% |
| Wegovy (semaglutide) once a week injection | 15% |
| Wegovy (semaglutide) once a day oral route | 15.1% |
| Mounjaro (tirzepatide) once a week injection | 15.7% |
Recommended Reading: Is an oral version of semaglutide as effective as the injectable version?
How is tirzepatide (Mounjaro) administered?
Mounjaro is self-administered once weekly through injection under the skin of the abdomen, thigh or upper arm. The exact dosage needed for weight loss depends on the individual – the specific dosage and dosing instructions must come from your doctor.
What are the more common side effects of tirzepatide (Mounjaro)?
Mounjaro can cause certain side effects, some being more common than others. Here are the most common side effects experienced by patients who took Mounjaro in clinical trials:
Nausea and diarrhea (which were reported to occur while the Mounjaro dose was increased)
Decreased appetite
Vomiting
Constipation
Indigestion
Stomach Pain
Mounjaro may cause serious side effects. Reported side effects include:
Severe digestive problems, which may lead to acute kidney injury
Gallbladder problems
Pancreatitis
Risk of thyroid cancer
Severe allergic reaction
Is tirzepatide right for you?
A good candidate for tirzepatide (Mounjaro) is someone with type 2 diabetes with overweight or obesity; or an individual with overweight or obesity (without type 2 diabetes).
Weight loss medications are most effective with lifestyle changes, including proper exercise and a healthy diet. Therefore it is important to have a holistic approach to weight loss.
Like most weight loss medications, tirzepatide is not available over the counter. It can only be obtained by prescription, so you will have to consult a doctor in order to get them.
At the moment, tirzepatide (Mounjaro) is still not available in Singapore. If you are interested in tirzepatide or other GLP-RA medications, please send us a message on WhatsApp.
You might want to learn more about NOVI Optimum Plus.
This is a medical weight loss program that is centered on safe and proven weight loss medications supported by a healthy lifestyle for weight loss that lasts. Our patients receive personalized nutrition and fitness advice from a dedicated health coach, to help them develop and stick to a healthy lifestyle plan.