UK regulator approves a diabetes drug for weight management in obese and overweight patients

The Medicines and Healthcare products Regulatory Agency (MHRA) has today (8 November 2023) authorized via a national application route, a new indication for the diabetes medicine, Mounjaro (tirzepatide), for weight loss and weight management in adults aged 18 and over.

Mounjaro is now authorized for adult patients with a BMI of 30 kg/m2 or more (obesity), as well as those with a BMI between 27-30 kg/m2 (overweight) who also have weight-related health problems such as prediabetes, high blood pressure, high cholesterol, or heart problems.

The medicine is to be used together with a reduced-calorie diet and increased physical activity.

The active ingredient in this treatment, tirzepatide, works by regulating a patient’s appetite so they feel full, making them feel less hungry and experience fewer food cravings.

Mounjaro is available for weight management as a pre-filled injection pen filled with 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg of tirzepatide, injected under the skin of a patient’s stomach area, thigh or upper arm.

The starting dose is 2.5 mg once a week for four weeks, increasing to 5 mg once a week. The dose may then be increased in at least 4-week intervals up to the maximum dose of 15 mg once weekly, if recommended by the patient’s doctor.

Obese or overweight female patients using oral contraceptives should consider also using a barrier method of contraception (e.g., a condom) or switching to a non-oral contraceptive method for 4 weeks after starting Mounjaro and for 4 weeks after each increase in dose as Mounjaro may affect how well the contraceptive pill works in these patients.

We have prioritized rapid assessment of this new indication for Mounjaro, given the public health importance of access to new medicines to help tackle obesity. We have drawn on advice from the independent Commission on Human Medicines in coming to our decision, and as with all products, will keep the safety of Mounjaro under close review."

Julian Beach, Interim Executive Director for Healthcare Quality and Access, MHRA

The new weight management indication is based on the results of two international, randomized double-blind, placebo-controlled clinical trials, SURMOUNT-1 and SURMOUNT-2, in overweight and obese adult patients with and without diabetes.

The studies showed that patients who were treated with tirzepatide had a significant weight loss over time compared to patients who took a placebo.

In SURMOUNT-1, 2,539 obese or overweight adults with at least one weight-related complication (that was not diabetes) were given either weekly 5 mg, 10 mg or 15 mg tirzepatide, or a placebo over a 72-week period. The average percentage change in weight over the trial period was -16.0% for the 5 mg dose, -21.4% for the 10 mg dose, -22.5% for the 15 mg dose and -2.4% for the placebo. In addition, 89.4% (5 mg), 96.2% (10 mg) and 96.3% (15 mg) of patients taking tirzepatide lost at least 5% of their body weight compared to 27.9% of those taking the placebo.

In SURMOUNT-2, 938 obese or overweight adults with Type-2 diabetes were given either weekly 10 mg or 15 mg tirzepatide or a placebo over a 72-week period. Mean percentage change in weight over the trial period was -13.4% for the 10 mg dose, -15.7% for the 15 mg dose and -3.3% for the placebo. In addition, 81.6% (10 mg) and 86.4% (15 mg) of patients taking tirzepatide lost at least 5% of their body weight compared to 30.6% of those taking the placebo.

The most common side effects of the medicine are nausea, diarrhea, vomiting (which usually goes away over time), and constipation. Low blood sugar (hypoglycemia) is also very common in patients with diabetes. Symptoms of this can include headache, drowsiness, weakness, dizziness, feeling hungry, confusion, irritability, fast heartbeat and sweating.

As with any medicine, the MHRA will keep the safety and effectiveness of Mounjaro under close review. Anyone who suspects they are having a side effect from this medicine are encouraged to talk to their doctor, pharmacist or nurse and report it directly to the Yellow Card scheme, either through the website ( or by searching the Google Play or Apple App stores for MHRA Yellow Card.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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