The first quarter of 2026 saw Eli Lilly’s tirzepatide diabetes brand Mounjaro take the top spot in the quarterly best-seller rankings. This ended Merck & Co.’s Keytruda’s (pembrolizumab) run, since Q1 2023, as the world’s highest-selling drug on a quarterly basis. Mounjaro recorded $8.66bn in Q1 2026 sales, more than doubling year-on-year and a $1.25bn sequential gain over Q4 2025.
Mounjaro is also forecast to oust Keytruda as the world’s best-selling drug on an annual level as well this year...
