Many users reported losing significant amounts of weight and achieving better control of their blood-glucose level after taking the injectable drug, which contains the active ingredient tirzepatide.
With the drug’s significant benefits widely recognised, there were forecasts that sales next year could approach $5 billion and that it could ultimately become one of the best-selling drugs of all time.
However, supplies in the US have been affected by shortages and price increases, and many patients have had to stop taking the drug. Enthusiasm on social media, driven largely by celebrities and influencers, also fuelled the shortages. Even high demand for the over-the-counter drug in the UAE resulted in a shortage. Can it deliver on its promise?
What is Mounjaro?
Mounjaro is an injectable drug from the American drug company Eli Lilly used chiefly to treat diabetes and was approved for use in the UAE, US and Europe last year.
Its active ingredient is an engineered protein that activates receptors for GLP-1 (glucagon-like peptide) and GIP (glucose-dependent insulinotropic polypeptide), which are hormones that the intestine secretes when a person consumes glucose or other foods. They essentially cause more insulin to be released and lower blood sugar levels. GLP-1 is also known to suppress appetite.
Certain other injectable Type 2 diabetes or anti-obesity medications, such as Ozempic, target GLP-1 but not GIP, and in trials have not led to such significant weight loss.
"I think tirzepatide is really the next step up from the injectable therapeutics around for the last 10 years," said Richard Holt, professor in diabetes and endocrinology at the University of Southampton in the UK.
"Tirzepatide … appears to have additional benefits, which means that it’s the drug that leads to the greatest reduction."
In a clinical trial, the results of which were published last year, Mounjaro resulted in an average loss of 22.5 per cent of body weight at the highest dose after 72 weeks of treatment.
Diabetes and obesity are global health issues. According to the World Health Organisation, diabetes affects 422 million people worldwide, while more than a billion people worldwide are obese. Diet, lifestyle changes and proper treatment can all help.
Mounjaro's effects, often greater than those of lifestyle changes, have been likened to having a gastric band placed around the stomach to make the person feel fuller, a procedure known as bariatric surgery.
Typically, any side effects are modest, and may include, according to the drug's producer, nausea, vomiting, constipation, indigestion and stomach (abdominal) pain.
What is Ozempic?
Ozempic is a brand name for a drug that contains the active ingredient semaglutide, which is also sold under the names Wegovy and Rybelsus.
As with Mounjaro, these drugs activate GLP-1 receptors but, unlike Mounjaro, they do not target GIP receptors.
Ozempic appears to have less of an effect than Mounjaro, with a 2021 study indicating that it resulted in an average of 16.9 per cent reduction in body weight.
This is nonetheless a substantial effect, enough that after the results of the study were released, one doctor described semaglutide as "the most impactful medication for the treatment of obesity".
Later in 2021, the US Food and Drug Administration (FDA) approved the use of Wegovy for weight management in obese adults, or overweight adults who also have high blood pressure, Type 2 diabetes or high cholesterol. Wegovy is also recommended for children aged 12 years and over who are obese.
In some countries, such as the UK, Ozempic is recommended only for people with Type 2 diabetes.
As with Mounjaro, any side effects with Ozempic are usually mild, including, for example, nausea, vomiting, stomach (abdominal) pain, headache and dizziness.
What is happening with Mounjaro?
Huge demand for Mounjaro, sparked by very cheap introductory prices, some as low as $25 a month, resulted in shortages of the drug in the US.
While the FDA lists all doses of Mounjaro/tirzepatide as being available, the drug is still on the organisation’s shortage list.
Some people have seen the drug’s cost increase to a reported $1,000 a month, making it unaffordable for many whose insurance will not cover the cost.
In the US its use is approved by the FDA to reduce blood sugar levels only for Type 2 diabetics. It has already been used by many obesity patients and reports indicate that this use of the drug is likely to secure FDA approval later this year. Mounjaro is available from UAE online retailers, but it requires a prescription. Shortages have also been reported in the UAE.
"It certainly leads to weight loss as well as improvements in glucose control. There are potential benefits for people with both conditions [obesity and Type 2 diabetes]. I suspect some people who just have obesity may well benefit," Prof Holt said.
While Mounjaro is seen as a step forward from previous drugs, Prof Holt said he expected even more effective medications to come on to the market in future.
"What we will find in due course is that there are going to be further dual and even triple agents in development that will take it a step further," he said.