The Shifting Landscape of Pharmaceutical Dominance
The pharmaceutical industry is in a constant state of flux, with blockbuster drugs rising and falling due to patent expirations, new clinical discoveries, and shifting market demands. For the second consecutive year, Merck's Keytruda (pembrolizumab) holds the title of the world's best-selling drug, generating an impressive $29.5 billion in sales in 2024 [1.2.1, 1.2.2]. This represents an 18% year-over-year increase, solidifying its place at the pinnacle of the pharmaceutical market and dethroning the long-reigning champion, AbbVie's Humira [1.2.1, 1.3.3].
Keytruda's Reign: A Story of Immuno-Oncology
Keytruda's success is a testament to the transformative power of immuno-oncology. It is a humanized monoclonal antibody that works as a PD-1 inhibitor [1.4.3]. In simple terms, it blocks a specific pathway (PD-1/PD-L1) that cancer cells use to hide from the body's immune system. By blocking this interaction, Keytruda helps restore the immune system's ability to recognize and attack tumor cells [1.4.3].
Its market dominance is driven by several factors:
- Broad Indications: Keytruda is approved for more than 40 indications across various cancer types, including non-small cell lung cancer, melanoma, head and neck cancer, and gastric cancer [1.2.1, 1.4.5]. This wide range of applications makes it a cornerstone therapy in modern oncology.
- Early-Stage Treatment: The drug's sales are increasingly boosted by its use in earlier-stage cancers, often in combination with chemotherapy, to prevent recurrence after surgery [1.4.1, 1.4.5].
- Continued Innovation: Merck is actively developing new formulations, such as a subcutaneous (under-the-skin) injection, to offer greater convenience and potentially extend its market exclusivity beyond the primary patent expiry in 2028 [1.4.2, 1.4.5].
The Challengers: GLP-1 Agonists and Other Powerhouses
While Keytruda sits comfortably at the top, other drugs are experiencing phenomenal growth. The most notable are the GLP-1 receptor agonists, particularly Novo Nordisk's Ozempic (semaglutide). Originally approved for type 2 diabetes, Ozempic's significant weight-loss side effect has led to a surge in demand [1.2.8, 1.6.6]. In 2024, Ozempic sales jumped 26% to approximately $16.7 to $18.6 billion, making it the second or third best-selling drug globally depending on the report [1.2.1, 1.2.4, 1.2.5]. Combined with its sister drug for obesity, Wegovy, the semaglutide franchise represents a major force poised to challenge for the top spot in the coming years [1.3.3, 1.6.6].
Meanwhile, AbbVie's Humira (adalimumab), which was the world's best-selling drug for a decade, has seen its sales plummet [1.2.1, 1.3.8]. After losing patent exclusivity in the U.S. in 2023, the entry of multiple biosimilar competitors caused its revenue to drop by over 37% in 2024 to around $9 billion [1.2.1]. This steep decline highlights the critical role of patent cliffs in the pharmaceutical industry. To compensate, AbbVie has successfully transitioned its focus to newer immunology drugs like Skyrizi and Rinvoq, which are now generating substantial revenue [1.2.1].
Comparison of Top-Selling Drugs (2024 Data)
| Drug Name (Generic) | Manufacturer(s) | 2024 Sales (USD) | Mechanism of Action | Primary Use |
|---|---|---|---|---|
| Keytruda (pembrolizumab) | Merck & Co. | ~$29.5 Billion [1.2.1, 1.2.2] | PD-1 Inhibitor [1.4.3] | Cancer (Multiple Types) [1.4.5] |
| Ozempic (semaglutide) | Novo Nordisk | ~$17.5 Billion [1.2.3] | GLP-1 Receptor Agonist [1.6.3] | Type 2 Diabetes, Cardiovascular Risk Reduction [1.2.8] |
| Eliquis (apixaban) | Bristol Myers Squibb & Pfizer | ~$20.7 Billion (Combined) [1.2.4] | Factor Xa Inhibitor | Blood Clot Prevention [1.2.2] |
| Dupixent (dupilumab) | Sanofi & Regeneron | ~$15.1 Billion [1.2.4, 1.2.5] | IL-4 and IL-13 Inhibitor | Eczema, Asthma, COPD [1.2.1, 1.2.2] |
| Biktarvy (bictegravir, etc.) | Gilead Sciences | ~$13.4 Billion [1.2.2, 1.2.4] | Antiretroviral Therapy | HIV Treatment [1.2.1] |
| Skyrizi (risankizumab) | AbbVie | ~$11.7 Billion [1.2.1, 1.2.2] | IL-23 Inhibitor | Psoriasis, Crohn's Disease [1.2.1] |
| Humira (adalimumab) | AbbVie | ~$9.0 Billion [1.2.1] | TNF-alpha Inhibitor [1.5.9] | Autoimmune Diseases [1.5.1] |
Conclusion: A Market in Motion
The answer to "What is the most selling drug in the world?" is currently Keytruda, which has successfully capitalized on the immuno-oncology revolution. However, the pharmaceutical leaderboard is far from static. The meteoric rise of GLP-1 agonists like Ozempic for diabetes and weight management signals a major shift in market dynamics, with analysts projecting this class of drugs could become the new leader in the near future [1.3.3, 1.2.8]. Simultaneously, the sharp decline of former giant Humira serves as a stark reminder of the lifecycle of blockbuster drugs and the powerful impact of patent expirations and biosimilar competition [1.2.1, 1.5.3]. The coming years will be defined by this interplay between oncology innovation, the expanding metabolic disease market, and strategic lifecycle management.
For more information on the mechanism of action of Keytruda, you can visit Merck's official page.
