Eli Lilly’s diabetes drug Mounjaro has become the world’s top-selling medication, surpassing Merck’s cancer therapy Keytruda.
Mounjaro generated $8.7 billion in first-quarter sales for Eli Lilly, a 125% increase year over year, according to the company’s April 30 earnings release. Meanwhile, Merck reported Keytruda and Keytruda Qlex sales of $8.0 billion for the quarter, up 12%, in its own April 30 release. Keytruda had held the top spot since the first quarter of 2023, when it overtook AbbVie’s Humira, according to pharmaceutical sales tracking by Scrip.
Lilly’s performance compounded when Mounjaro and weight-loss drug Zepbound were combined. The medications, which use the same active ingredient tirzepatide, generated approximately $36.5 billion in 2025, according to Lilly’s quarterly filings. Merck reported full-year 2025 Keytruda sales of $31.7 billion in its fourth-quarter earnings release.
Keytruda’s core patent expires in 2028, and Merck has said it expects U.S. sales to decline after that time, according to the company’s annual filing with the Securities and Exchange Commission. The company is working to diversify its pipeline, reporting positive late-stage results from 18 phase 3 trials in 2025.
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