US-based pharma giant Eli Lilly’s diabetes and obesity drug Mounjaro has emerged as the world’s top-selling medicine, overtaking Merck’s blockbuster cancer therapy Keytruda in a major shift for the global pharmaceutical industry.
Keytruda, with pembrolizumab as its active ingredient, an immunotherapy drug by another US-based pharma major, Merck & Co is used in the treatment of nearly 22 different types of cancer.
The development also underscores the explosive rise of obesity and metabolic treatments, which are rapidly reshaping drug markets worldwide.
According to the World Health Organisation (WHO), in 2022, 1 in 8 adults in the world, 890 million or 89 crore people, were living with obesity. Also, globally, 590 million or 59 crore adults have diabetes.
According to the latest global sales data, Mounjaro generated $8.7 billion in revenue during the first quarter of 2026, surpassing Keytruda’s $7.9 billion sales during the same period. Keytruda had held the top position globally since 2023, when it overtook AbbVie’s Humira.
The rise of Mounjaro has been equally dramatic in India.
Pharmarack data showed the drug became the country’s highest-selling medicine by value in April and has maintained the top spot consistently since October last year, just months after its launch in India in March 2025.
Over the past year, Mounjaro recorded sales of nearly Rs 1,009 crore in the domestic market, highlighting strong demand for anti-obesity and diabetes therapies among Indian patients.
The drug’s rapid ascent reflects a broader global shift toward GLP-1 and dual-action metabolic medicines, which are increasingly being viewed as the pharmaceutical industry’s biggest growth engine.
Mounjaro contains tirzepatide, a molecule that targets both GLP-1 and GIP receptors and is prescribed for diabetes and weight management. Analysts have long predicted that Lilly’s tirzepatide franchise could become one of the most commercially successful drug portfolios in pharmaceutical history.
INDIA DEMAND CONTINUES TO SURGE
India has emerged as one of Lilly’s fastest-growing markets for the therapy. The company has already indicated plans to strengthen its manufacturing and supply partnerships in the country, viewing India as both a high-growth consumer market and a potential export hub for global operations.
The strong uptake comes despite rising competition from semaglutide-based therapies and the entry of multiple generic versions after patent expiries.
Novo Nordisk had also launched injectable semaglutide – Wegovy and Ozempic in India last year, but in March this year, the patent on the molecule expired, leading to a flood of cheaper versions in the country.
Even after a flood of cheaper semaglutide alternatives entered the Indian market earlier this year and shook its ground to some extent, Mounjaro retained leadership in sales by value, underlining the preference among many physicians and patients for newer-generation weight-loss and diabetes treatments.
How exactly the semaglutide generics have affected Mounjaro’s market in India, will however, be known once the detailed market report for the month of April is released by Pharmarack.
Globally, Lilly’s obesity and diabetes franchise has become the company’s biggest growth driver. When sales of Mounjaro and obesity drug Zepbound are combined, the tirzepatide portfolio generated about $36.5 billion in 2025, comfortably ahead of Keytruda’s annual sales of $31.6 billion.
The performance has helped Lilly outperform expectations this year.
The company recently raised its annual revenue and profit guidance after reporting strong quarterly demand for both Mounjaro and Zepbound. Overall GLP-1 drug sales for Lilly reached $12.9 billion in a single quarter, reflecting the scale of demand for obesity therapies globally.
For India, Mounjaro’s success signals another important trend: patients are increasingly willing to spend on premium chronic therapies that promise significant lifestyle and health benefits, say doctors.
– Ends