Mounjaro, labelled the ‘King Kong’ of a new generation of slimming jabs, has been approved for us on the NHS for some diabetes patients.
However, many are eagerly interested in its use as a weight-loss drug in the UK after clinical trials showed people on it could shed 20 per cent of their body weight.
While Mounjaro, the brand name of the drug tirzepatide, hasn’t yet been approved for those looking to shed pounds, private clinics can offer the drug for this purpose via method through ‘off-label’ prescribing.
MailOnline has set out all you need to know about the latest weight shedding drug to be approved in the UK.
Tirzepatide, sold under the brand name Mounjaro, has been approved for use for diabetics in the NHS
What is Mounjaro?
Mounjaro is the brand name of a drug called tirzepatide, made by US pharmaceutical giant Eli Lilly.
The drug is taken once a week via an injection and helps boost the production of insulin, the hormone that regulates blood sugar, to control type 2 diabetes.
Mounjaro patients typically start on a 2.5 mg-dose injection once per week for four weeks.
This dose is gradually bumped up by an additional 2.5mg every four weeks.
The highest dose of Mounjaro that has been studied is 15mg, so that will likely be the maximum dose a doctor will prescribe.
Mounjaro is the latest in a family of new generation dugs that could help people lose weight, similar to its rival Wegovy.
Experts hope these drugs will provide a radical new way to treat obesity, an issue that costs the NHS an estimated £6.5billion each year.
The above graphic shows how weight-loss drug tirzepatide works. It works to suppress hunger by mimicking hormones indicating that the body is full. It also shows the passage of food through the stomach by reducing the production of stomach acid and contractions of the muscle
How does it work for weight loss?
Tirzepatide belongs to a class of drugs called GLP-1 agonists, which mimic a natural hormone that tells the body when it’s full, suppressing the appetite.
This helps reduce food and calorie intake, leading to people lose more weight than they normally would in combination with diet and exercise.
But as opposed to competitors, it also mimics a second hormone which influences appetite called glucose-dependent insulinotropic polypeptide (GIP), compounding compounds the weight loss effect.
Some patients already taking the drug have shared their results on social media, with one overweight man claiming that it helped him shed 100lbs (45.4kg).
How effective is it compared to Ozempic and Wegovy?
Clinical trials found that after just one year, a third of type 2 diabetics taking Mounjaro lost more than 20 per cent of their body weight.
This is more that the weight loss observed for rival jabs Ozempic and Wegovy.
These drugs, made by Danish firm Novo Nordisk, use a different ingredient called semaglutide, also a GLP-1 agonist.
Ozempic is a specific formulation to help manage diabetes, whilst Wegovy is more potent and designed to treat obesity.
Patients on Ozempic could shed up to 10 per cent of their body weight whilst those on Wegovy could lose around 15 per cent.
The difference in results led US diabetes expert Dr Julio Rosenstock to declare Mounjaro ‘King Kong’ compared to ‘the gorilla’ of its rival Wegovy.
It’s important to note that these figures are the upper ranges of the weight loss patients experienced and individual results could vary.
Does it have any side effects?
Clinical trials have reported a number of side effects from taking Mounjaro.
One involving 900 participants found a fifth suffered from nausea and diarrhoea, and about one in 10 reported vomiting or constipation.
Eli Lilly said Mounjaro’s side effects were most commonly reported during the dose escalation period.
Only about 4 per cent and 7.5 per cent of participants, in the 10mg and 15mg dosing cohorts respectively, quit the study due to side effects.
Other people, taking the drug outside of clinical trials, have reported experiencing hair loss while taking Mounjaro.
There has also been a suggested link to an increased risk of cancer from the jab.
EU drug watchdog, the European Medicines Agency (EMA), said earlier this year that research on rodents has suggested the artificial hormones packaged in tirzepatide could raise the risk of medullary thyroid cancer.
The EMA has ruled that a monitoring study of patients taking the drug is required to explore the potential of a raised cancer risk in humans.
According to the latest data digestive problems were the most commonly reported side effects of tirzepatide, the active ingredient of Mounjaro. These included about one in five participants suffering from nausea and diarrhoea, and about one in 10 reporting vomiting or diarrhoea
Who can currently get it?
As it stands, no one. Though that is expected to change shortly.
Yesterday, the National Institute for Health and Care Excellence (Nice) recommended Mounjano as a diabetes medication, to be prescribed alongside diet and exercise.
However, supplies are not expected to arrive in the UK until October.
When they do arrive, about 180,000 NHS patients with type 2 diabetes will be eligible to be given tirzepatide eventually.
While not yet approved for weight loss specifically some Americans are already using it ‘off label’. One of these is Matthew Barlow, a 48-year-old health technology executive living in California, who said he has lost more than 100 pounds since November by using Mounjaro and changing his diet
Can it be used for weight loss?
Nice is expected to make a decision on if tirzepatide can be used for weight loss within the next few months.
If approved, it is likely to have similar rules regarding its use on the NHS as Wegovy.
NHS patients can only be prescribed Wegovy if they have a body mass index (BMI) of 30 or higher — or a BMI of more than 27 and at least one weight-related illness — who commit to dieting and exercise plans are eligible.
However, this will not stop private clinics from dishing out tirzepatide for weight loss once UK supplies for diabetics come online.
Private clinics can do this via ‘off-label’ prescribing.
This is a system where medics can dish out a drug approved in the UK but for a different purpose than why it was approved.
In this example, this could see a medic prescribe tirzepatide, a diabetes medication, for a patient wanting to lose weight.
Similar private off-label prescriptions were seen for Ozempic before UK supplies of Wegovy became available.
This has contributed to shortages, with some diabetes patients missing out on their prescriptions for diabetes medication as a result.
Some medics have also raised concern that private clinics snapping up supply of these drugs could stop the patients with the greatest medical need for the drugs having to go without.
How much could it cost?
NHS patients would only have to pay £9.65 for their dose in England.
However, in practice, many will get it for free under an exemption rule that waives prescription charges for people with certain health conditions.
Most UK private clinics are yet to reveal what prices they would charge patients to access Mounjaro, but some have already listed it at £119 for a starting dose.
This is a far cry from what people pay in the US, where the price can be over $1,000 a dose (about £820) depending on a patient’s insurance.
Elon Musk (left) credits his spectacular weight loss in 2020 to Wegovy. The tech tycoon looked noticeably slim when he first arrived in Twitter HQ after purchasing the company in October (right)
Could we see shortages similar to Ozempic?
Possibly. Demand for semaglutide soared after the results of Wegovy clinical trials, leading patients to opt for Ozempic as an alternative.
This isn’t just a UK problem. Global interest in the drugs including its public health potential to help combat obesity have led to a global shortage.
But it is hoped that these supply issues will be reduced as more of these drugs, such as Mounjaro come online.