Yahoo News What is Mounjaro? The Ozempic-style weight-loss drug being rolled out on the NHS
They’ve been heralded as the magic drugs that treat obesity when diet and exercise have failed. But Ozempic and Wegovy – and their newer cousin, Mounjaro – are expensive, and mostly only available on private prescription.
For the past year, overweight Britons have been waiting for these medications to become more available on the NHS. But last week, the hopes of millions were dashed when Nice (the National Institute for Health and Care Excellence) made the “difficult decision” that Mounjaro would only be available to a limited number of people.
More than one in four UK adults are obese, but only a minuscule 220,000 people (that’s one in 340) will now be eligible for Mounjaro. So what is the drug, and why is it such a big deal?
What is Mounjaro?
The drug Mounjaro (also known as tirzepatide) is a synthetic “analogue” of the two molecules GLP-1 (glucagon-like peptide-1) and GIP (gastric inhibitory polypeptide). These hormones, which are also produced naturally in the brain, regulate appetite and insulin production.
Mounjaro was originally developed for the treatment of Type 2 diabetes, but is now increasingly used for weight loss. A clinical 72-week trial published in the New England Journal of Medicine in 2022 showed that, in participants with obesity, a weekly dose of tirzepatide provided “substantial and sustained reductions” in body weight, between 15 and 20 per cent.
The medication comes in a preloaded injection pen in doses from the “starter” dose of 2.5mg, up to 15mg. Patients inject it into the stomach, thigh or upper arm.
“I’ve been a doctor for over 30 years, and only a few drugs have made me say, ‘oh my God’,” says Prof Ketan Dhatariya, consultant in diabetes, endocrinology and general medicine at the Norfolk & Norwich University Hospital. “Mounjaro is definitely one of them. Its implications for the future of medicine are ground-breaking,” says Dhatariya, who is also honorary professor of medicine at the University of East Anglia.
How does Mounjaro work?
“The main effect of the hormones in Mounjaro is to tell you that you are ‘full’,” says Dhatariya. “Imagine you’ve been invited to a friend’s house for dinner, and the food isn’t ready yet, so you fill up on Twiglets and Pringles. But when the meal is served, you are no longer hungry and you can’t eat a thing.”
The drug works in a number of ways, says Dhatariya. “First of all, it works on the reward and satiety centres in your brain. Mounjaro also stimulates insulin production – so whether you have Type 2 diabetes or not, you will lose weight.” In fact, he says, weight loss has shown to be more marked in those who do not have Type 2 diabetes.
“Mounjaro helps get rid of excess cholesterol and improves your liver health, as well as slowing the passage of food through the gut, so you feel fuller for longer,” says Dhatariya.
How is Mounjaro (tirzepatide) different from Ozempic or Wegovy (semaglutide)?
Ozempic – or semaglutide – which was approved for use in 2017, was the first of the new-generation weight-loss drugs to hit the headlines in the United States, swiftly being taken up by celebrities including Oprah Winfrey and Sharon Osbourne. (Wegovy is the version of semaglutide that’s available in the UK.) But tirzepatide (Mounjaro) has since been shown to pack more of a punch.
“Semaglutide contains just one molecule, GLP-1,” says Dhatariya. “But two thirds of Mounjaro comes from the second agent, GIP. The combination is far more efficacious, both for those with Type 2 diabetes, and for those who want to lose weight.”
A July 2024 study published in the Journal of the American Medical Association (JAMA) showed that – in a population of adults who were overweight or obese – tirzepatide (Mounjaro) was associated with significantly greater weight loss than semaglutide.
What are the side effects of Mounjaro?
The side effects of Moujaro include:
Nausea
Sickness
Sometimes constipation or diarrhoea
“But it’s important to note that all drugs have side effects,” says Dhatariya. “These adverse effects are usually transient and only tend to come back when the drug is first started, or when the dose is increased. It’s very rare for side effects to continue, and I encourage my patients to stick with their treatment.”
Very rarely, Mounjaro can cause an allergic reaction, pancreatitis or kidney damage.
Can you get Mounjaro on the NHS in the UK?
As things stand, Mounjaro is only currently available on the NHS for the treatment of Type 2 diabetes. But in early December 2024, Nice published its final draft decision of Mounjaro for treating obesity (though the final decision is expected some time in January). Nice has now recommended Mounjaro for use as a medication for weight loss on the NHS when someone has a BMI of at least 35, and they have additional medical conditions that are related to obesity including Type 2 diabetes or high blood pressure – it also extends to those who are at high risk of Type 2 diabetes.
Under the draft Nice guidelines, a lower BMI would apply to people from black African, African-Caribbean, Asian, Chinese and Middle Eastern backgrounds, who have additional medical conditions that are related to obesity.
Where else can you get Mounjaro – and how?
Mounjaro is available in private weight-loss clinics, online pharmacies including Boots and Superdrug and digital providers such as Second Nature.
Some sell the medication alone, while others – but not all – pair it with a lifestyle programme to further enhance the weight-loss results through healthy diet and exercise. Patients are required to fill in a questionnaire, which is then signed off by a medical professional. Other providers require the client to send recent photographs of themself: there doesn’t appear to be a consistent approach.
While Mounjaro is a safe and effective medication when prescribed responsibly, cowboy clinics and fake prescriptions abound: make sure you do your research before you buy.
Who is eligible for Mounjaro privately?
In the UK, the rules are that Mounjaro can now be prescribed privately for adult patients with a BMI of 30 above, as well as those with a BMI between 27 and 30 who also have weight-related health problems such as pre-diabetes, high blood pressure, high cholesterol or heart problems. But not all clinics appear to check, or verify the customer’s BMI.
How much does it cost?
Mounjaro is free on the NHS; according to Dhatariya, the drug costs the NHS £92 per patient for a month’s supply.
Private Mounjaro can cost anywhere from £150 to £250 a month (which comprises four-weekly doses, by injection). There can also be add-ons for laxatives and anti-sickness medication.
FAQs
If I’m on Mounjaro, do I still need to eat healthily and exercise?
Yes, the experts agree that this is the best approach. Giles Yeo is professor of molecular neuroendocrinology at the Medical Research Council Metabolic Diseases Unit and scientific director of the Genomics Core at the University of Cambridge. “These drugs are very effective and they absolutely should be used, but a person still needs to make strides to ensure they remain sustainably healthy,” he says. “Hence, Mounjaro should come with a suite of wraparound treatment, including some form of dietary advice or intervention and probably some form of exercise regime.”
As well as causing a person to lose fat, Mounjaro can lead to loss of muscle mass, so it’s vital for people to continue or begin resistance or weight training.
“You still have to improve your diet, you still have to improve your lifestyle, and for lack of a better term, your behaviour,” says Yeo. “There is no free lunch.”
If I come off Mounjaro will I gain weight again?
Yes, this is quite likely to happen. “The majority of patients will regain weight if they stop the medication,” says Dr Dan Azagury, a bariatric surgeon and medical director at Stanford University.
A study published in 2022 in the journal Diabetes, Obesity and Metabolism came to a similar conclusion on recent studies on semaglutide. Two thirds of patients who stopped taking the drug suffered from a “rebound effect”, and gained two thirds of the weight they had lost after one year.
What else does Mounjaro have the potential to treat?
“It’s now being investigated as a treatment for conditions including gambling and alcohol addiction, because the drug works on the reward centres in the brain,” says Dhatariya.
Semaglutide, the forerunner to tirzepatide (Mounjaro), is even being trialled as a treatment for Alzheimer’s disease. “It isn’t certain that the newer drugs will have the same ‘extracurricular’ benefits – only time will tell,” says Yeo. “What I do know is that there has never been a more exciting time to work in the field of obesity, certainly with regard to the number of treatment tools available now.”
