The diabetes drug Mounjaro has been authorised by the Medicines and Healthcare products Regulatory Agency for weight loss and weight management in people aged 18 and over.

Mounjaro, also known as tirzepatide, can be used by patients with a body mass index of 30kg/m² or more and those with a BMI between 27-30kg/m² who also have weight-related health problems including prediabetes, high blood pressure, high cholesterol or heart problems.  

The MHRA said Mounjaro, which is available as a pre-filled injection pen containing 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg of tirzepatide and is injected into the stomach, thigh or upper arm, should be taken “together with a reduced-calorie diet and increased physical activity.”

The regulator also said 2.5mg at first should be taken once a week for four weeks before increasing to 5mg once a week. The dosage can then be increased in at least four-week intervals up to a maximum dose of 15mg once a week but only if recommended by a doctor.

The MHRA advised obese or overweight female patients using oral contraceptives to consider using a barrier method of contraception such as a condom or switching to a non-oral contraceptive method for four weeks after starting Mounjaro and for four weeks after each increase in dose because the drug could affect the contraceptive pill’s effectiveness.

The MHRA ’s decision is based on the results of two international, randomised double-blind, placebo-controlled clinical trials known as SURMOUNT-1 and SURMOUNT-2 in overweight and obese adult patients with and without diabetes.

During SURMOUNT-1 which involved 2,539 obese or overweight adults with at least one weight-related complication that was not diabetes, the average weight loss was 16 per cent for the 5mg dose, 21.4 per cent for the 10mg dose, 22.5 per cent for the 15mg dose and 2.4 per cent for the placebo over a 72-week period.

During SURMOUNT-2, which involved 938 obese or overweight adults with Type-2 diabetes, the mean percentage reduction in weight over 72 weeks was 13.4 per cent for the 10mg dose, 15.7 per cent for the 15mg dose and 3.3 per cent for the placebo.

Julian Beach, interim executive director, healthcare quality and access at the MHRA , said: “We have prioritised 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.”