Eli Lilly and Company’s antidiabetic drug tirzepatide, which is sold as Zepbound and Mounjaro, has been granted expanded regulatory approvals in the US and the UK.

The US Food and Drug Administration (FDA) and the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) have authorised a new indication for tirzepatide.

Tirzepatide is the first and only treatment that works by activating both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) hormone receptors.

It is already approved as a once-weekly treatment, adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes.

The current FDA and MHRA approvals will expand its indication to include chronic weight management in adults, as an adjunct to a reduced-calorie diet and increased physical activity.

Tirzepatide is now indicated for adults with obesity (body mass index (BMI) of 30kg/m2 or higher), or overweight, (BMI of 27kg/m2 or above), with at least one weight-related comorbidity.

The weight-related comorbidities may include hypertension, dyslipidemia, type 2 diabetes mellitus, obstructive sleep apnea or cardiovascular disease.

Lilly diabetes and obesity global medical affairs senior vice president Leonard Glass said: “Unfortunately, despite scientific evidence to the contrary, obesity is often seen as a lifestyle choice – something that people should manage themselves.

“For decades, diet and exercise have been a go-to, but it’s not uncommon for a person to have tried 20-30 times to lose weight with this approach.

“Research now shows that the body may respond to a calorie-deficit diet by increasing hunger and reducing feelings of fullness, making weight loss more difficult. Lilly is aiming to eliminate misperceptions about this disease and transform how it can be managed.”

The FDA and MHRA approvals are supported by the results from SURMOUNT-1 and SURMOUNT-2 clinical trials in overweight and obese adult patients with and without diabetes.

In the SURMOUNT-1 study, 2,539 obese, overweight adults with weight-related comorbidity were given tirzepatide weekly 5mg, 10mg or 15mg or placebo, in addition to diet and exercise.

In the SURMOUNT-2 trial, 938 obese or overweight adults with Type-2 diabetes were given either tirzepatide weekly 10mg or 15mg or a placebo over a period of 72 weeks.

The most common side effects include nausea, diarrhoea, vomiting, and constipation, with hypoglycaemia very common among patients with diabetes.

In both studies, patients who were treated using tirzepatide showed significant weight loss over time, compared to patients who received a placebo.

Tirzepatide is recommended for use with a reduced-calorie diet and increased physical activity and is not recommended for use with other tirzepatide-containing products or any GLP-1 receptor agonists.

Furthermore, the drug may cause tumours in the thyroid, including thyroid cancer, and its users are advised to contact their healthcare provider if any symptoms are observed.

MHRA healthcare quality and access interim executive director Julian Beach 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.”