Home » GLP-1 Weight Loss Injections in the UAE » Tirzepatide: How the Medication in Mounjaro Works and What the Trials Show

Tirzepatide: How the Medication in Mounjaro Works and What the Trials Show

Quick answer

Tirzepatide is a once-weekly injection, prescribed in the UAE as Mounjaro at strengths from 2.5 mg to 15 mg. It activates the receptors for two gut hormones, GIP and GLP-1, which can reduce appetite and help the body release insulin when blood sugar rises. A 72-week clinical trial, SURMOUNT-5, compared it directly with semaglutide in adults with obesity or overweight. Adults taking tirzepatide lost around 20% of their body weight on average, against around 14% with semaglutide.

Key takeaways

The US Food and Drug Administration (FDA) prescribing information describes tirzepatide as binding to and activating both the GIP and GLP-1 receptors, the targets of two gut hormones.
Tirzepatide’s elimination half-life is around five to six days in people with overweight or obesity, which allows a single injection each week.
In SURMOUNT-1, a 72-week clinical trial in 2,539 adults with obesity or overweight, patients lost around 15% of their body weight on average at 5 mg and around 20% at 10 mg and 15 mg.
In the weight management trials, nausea was reported by 25% to 29% of adults taking tirzepatide, compared with 8% on placebo.
In the United States, tirzepatide is also approved to treat moderate to severe obstructive sleep apnoea in adults with obesity.
The prescribing information does not recommend combining tirzepatide with another tirzepatide product or with a GLP-1 medication such as semaglutide.
Treatment with tirzepatide at Endocare starts with a full assessment by one of our endocrinologists, who will discuss whether Mounjaro is appropriate for you.

In one line: Zepbound, the brand used in the United States for weight management, contains the same medication as Mounjaro.

01 Introduction

Tirzepatide is the active ingredient in Mounjaro, a medication made by Eli Lilly. Our endocrinologists prescribe it for weight management alongside a reduced-calorie diet and increased physical activity.

02 What is tirzepatide?

Tirzepatide is a medication that acts on two hormone receptors in the body. The StatPearls clinical reference on tirzepatide describes it as a dual agonist of the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. It is injected under the skin once a week.

03 How does tirzepatide work?

GIP and GLP-1 are hormones that the gut releases after eating. The Mounjaro prescribing information describes tirzepatide as selectively binding to and activating both receptors.

The NHS guidance on tirzepatide explains that it works for weight loss by reducing your appetite and helping you feel fuller for longer. For type 2 diabetes, the NHS describes it as helping the body make more insulin when it is needed and slowing digestion. The response differs from one patient to another.

The prescribing information for tirzepatide in weight management gives an elimination half-life of around five to six days in people with overweight or obesity. This long half-life allows a single injection each week.

04 Tirzepatide brands: Mounjaro and Zepbound

Mounjaro and Zepbound contain the same medication, tirzepatide. In the United States, the FDA has approved Mounjaro for type 2 diabetes in adults and in children aged 10 and older. It has approved Zepbound for weight management in adults with obesity, or overweight with a weight-related condition. Zepbound is also approved for moderate to severe obstructive sleep apnoea in adults with obesity.

In the European Union, Mounjaro is authorised for both weight management and type 2 diabetes, as the European Medicines Agency information on Mounjaro sets out. In the UAE, tirzepatide is available on prescription as Mounjaro at every strength from 2.5 mg to 15 mg. Our Mounjaro dosage guide explains the six strengths and how your endocrinologist increases the dose.

05 What the SURMOUNT trials show

Weight loss at each dose in the SURMOUNT-1 trial

SURMOUNT-1 was a 72-week Phase 3 clinical trial in 2,539 adults with obesity, or overweight with a weight-related condition, who did not have diabetes. The prescribing information for tirzepatide in weight management reports the following average change in body weight at week 72.

Weekly dose	Average change in body weight at 72 weeks (SURMOUNT-1 trial)
Placebo	-3.1%
Tirzepatide 5 mg	-15.0%
Tirzepatide 10 mg	-19.5%
Tirzepatide 15 mg	-20.9%

Patients on the 10 mg and 15 mg doses lost around 20% of their body weight on average. The response was not the same for every participant: around nine in ten participants on 15 mg lost at least 5% of their body weight, compared with around a third on placebo.

What happened when tirzepatide was stopped in the SURMOUNT-4 trial

The British Heart Foundation describes SURMOUNT-4, a clinical trial in which some participants were switched from tirzepatide to a placebo for a year. In an analysis of the SURMOUNT-4 trial, 82% of participants who stopped tirzepatide regained at least a quarter of the weight they had lost. Around 24% regained three quarters or more, and 9% regained all of it.

Participants continued to receive lifestyle counselling in the trial. When it is time to come off the medication, your endocrinologist will help plan whether and how to stop treatment and what support you will need afterwards. Coaching continues throughout. A gradual reduction in dose is an individual clinical approach, not a proven standard of care, and it has not been shown to prevent weight regain. Our guide on what happens when you stop taking Mounjaro explains the options.

06 Tirzepatide and semaglutide compared

One 72-week randomised clinical trial, SURMOUNT-5, compared tirzepatide and semaglutide directly. Patients taking tirzepatide lost around 20% of their body weight on average, against around 14% with semaglutide.

The trial enrolled 751 adults with obesity, or overweight with a weight-related condition, who did not have diabetes. Each medication was given at the highest dose each patient could tolerate: 10 mg or 15 mg of tirzepatide, or 1.7 mg or 2.4 mg of semaglutide. The American College of Cardiology summary of the SURMOUNT-5 trial reports average losses of 22.8 kg against 15.0 kg.

Tirzepatide and injectable semaglutide are both taken once a week, and both act on the GLP-1 receptor. Tirzepatide also acts on the GIP receptor. Semaglutide is the active ingredient in Ozempic, the Wegovy injection and the Wegovy pill.

Neither option is necessarily better. The right choice depends on your individual assessment, how well you tolerate treatment and what you can realistically sustain long term. Your endocrinologist will work through these factors with you. Two of our articles look at the brands side by side: Mounjaro, Ozempic and Wegovy compared and the difference between Ozempic and Wegovy.

For patients who prefer a tablet, Foundayo (orforglipron) is a once-daily option that acts on the GLP-1 receptor. Our page on weight loss pills covers the tablet options.

07 Tirzepatide side effects

In the weight management trials, nausea was reported by 25% to 29% of adults taking tirzepatide and diarrhoea by 19% to 23%, compared with 8% each on placebo. Not every patient experiences them. Side effects such as nausea or constipation can be particularly pronounced in the first few days at a new dose. They often improve as your body adjusts, although some symptoms last longer. Our page on tirzepatide side effects gives the figures for each side effect and the symptoms that need urgent advice.

08 Tirzepatide treatment at Endocare

Our endocrinologists prescribe tirzepatide as Mounjaro where it is appropriate, as part of our medical weight loss programme. Where possible, your first appointment takes place in person at Endocare’s Dubai clinic, as the physical examination and body composition analysis cannot be completed remotely.

Your endocrinologist will review blood tests from the last three months before prescribing. Monthly follow-up appointments can be held in person at the clinic or online. Endocare’s lifestyle coaches and our clinical nutritionist will work with you on nutrition, movement, sleep and stress.

Patients should not decide by themselves to start a GLP-1 medication. A doctor’s review is critical to ensure the treatment is safe and appropriate for the individual. Our pages on Mounjaro cost in the UAE and on Mounjaro in Dubai cover price and access.

09 FAQ

Is tirzepatide the same as Mounjaro?

Yes. Tirzepatide is the generic name of the active ingredient in Mounjaro, which is available in the UAE on prescription.

Is tirzepatide the same as Ozempic?

No. Ozempic contains semaglutide, which acts on the GLP-1 receptor, while tirzepatide acts on both the GIP and GLP-1 receptors. Ozempic is approved for type 2 diabetes.

Is there a generic version of tirzepatide?

In the UAE, tirzepatide is available on prescription as Mounjaro. The FDA’s information on unapproved GLP-1 medications states that unapproved and compounded products, including compounded tirzepatide, are not reviewed for safety, effectiveness or quality before they are marketed. Our article on compounded tirzepatide explains the risks.

How long does tirzepatide take to work?

Some patients start to see weight changes from around week two, while others take longer to respond. Early weight loss also does not necessarily continue at the same rate. Our guides on how long weight loss injections take to work and on your first month on Mounjaro explain the early weeks.

How long does tirzepatide stay in your system?

Tirzepatide has an elimination half-life of around five to six days in people with overweight or obesity, as its prescribing information reports. The NHS advises stopping tirzepatide at least four weeks before you start trying to become pregnant.

Who should not take tirzepatide?

Do not use tirzepatide if you or a member of your family has had medullary thyroid carcinoma, or if you have multiple endocrine neoplasia syndrome type 2. Tirzepatide should not be used during pregnancy. Our Mounjaro page sets out who may be suitable for treatment and the other reasons not to take it.

Book a consultation about tirzepatide at Endocare

At our Dubai clinic, your endocrinologist will assess you, review your blood tests and discuss whether Mounjaro is appropriate for you. You can book a weight loss consultation on +971 4 285 3885 or send us a message on WhatsApp.