Eli Lilly’s weight loss drug launches in India: Here are 4 things to know about Mounjaro

The drug — along with Novo Nordisk’s semaglutide marketed as Wegovy — has been much anticipated in India after its significant weight-loss effect was witnessed by many around the world. “Our mission of making life better for people living with obesity and diabetes in India is reflected in our efforts to accelerate the introduction of innovative medicines. The launch of Mounjaro demonstrates our ongoing support to this mission and our shared vision of a healthier nation,” said Winselow Tucker, president and general manager of Lilly India, in a release.

What is tirzepatide?

Tirzepatide belongs to a new class of diabetes medicines that were approved for the treatment of chronic obesity after they were found to be almost as effective as bariatric surgery for weight-loss. Called incretin mimetics, these drugs mimic the action of certain gut hormones to improve secretion of insulin, inhibit secretion of glucagon that stimulates glucose production in the liver, and also reduce appetite by slowing down digestion.

Tirzepatide acts on two targets — GLP-1 (glucagon-like peptide-1) hormone receptor and GIP (glucose-dependent insulinotropic polypeptide).

The medicine can help people lose just over 20% of their body weight on average, with nearly one in three persons dropping a quarter of their body weight. The drug is not a magic bullet, however. It has to be taken along-side a reduced-calorie diet and increased physical activity.

Who is the drug meant for?

The drug is meant to be prescribed to those who are obese with a BMI (body mass index) of over 30 or those who are overweight with a BMI between 25 and 29 with other weight-related co-morbid conditions such as diabetes and heart disease among others.

The drug should not be prescribed to people who have a family history of a particular type of thyroid cancer called medullary thyroid carcinoma (MTC) or a rare condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). It should be avoided in people who may have an allergic reaction to the medicine or its components.

With this class of medicines linked to side effects such as stomach paralysis, doctors also suggest avoiding the medication in patients with long-standing diabetes and sluggish peristalsis (contraction and relaxation of the digestive tract to push the food through) and gastric obstructions. They say it should also be avoided in patients prone to nausea as the medicine is known to lead to nausea and vomiting during the initial period.

What is the evidence available so far?

Several global clinical trials, which included participants from India, have been carried out to establish the safety and efficacy of the medicine.

SURMOUNT-1 — a study of 2,539 adults with obesity, or overweight with weight-related medical problems — found that the participants on 5 mg weekly dose lost on average 15% of their body weight in 72 weeks, those on 10 mg dose lost 19.5%, and those on the highest 15 mg dose lost 20.9%. To compare, those who were given a placebo lost only 3.1% of their body weight. The study found that nearly one in three persons put on the higher doses of the medicine lost nearly 25% of their body weight. To compare, only 1.5% of the people on placebo lost as much weight.

Another SURMOUNT-5 trial with 18,386 participants found tirzepatide to be more effective than its competitor semaglutide for weight loss. The study showed that participants on tirzepatide lost 20.2% of their body weight at 72 weeks as compared to 13.7% with semaglutide.

Importantly, SURMOUNT-4 trial with 670 participants showed that people regained the lost weight when they stopped taking the medicine. After taking the treatment for 36 weeks, those who stopped the once-a-week infusion gained back 14% of their body weight at 88 weeks. And, those who continued the treatment lost another 5.5% weight. The participants had lost around 20.9% of their total body weight during the 36 week treatment.

What did the regulator say?

The subject expert committee on endocrinology and metabolism, under the apex drug regulator Central Drugs Standard Control Organisation (CDSCO), recommended that permission be granted to Eli Lilly for importing and marketing the medicine in a single dose pre-filled pen and in a single-dose vial in June last year. The company was also given permission to import and market multi-dose pen by December.

The expert committee recommended a phase IV trial — or post-marketing surveillance — be carried out by the company, which helps in understanding long term safety of the drug, its effects on a diverse population, and rare side-effects, if any.