Determining which medication is the single most successful in the world is not as simple as it might seem. The title of "number one" depends on whether the ranking is based on global sales revenue, the total number of prescriptions dispensed, or another metric. While a high-cost cancer drug may lead in revenue, a widely used, low-cost generic for a chronic condition often dominates in volume. This article breaks down the different ways to measure a drug's success and introduces the market leaders in each category.
The Top Drug by Sales Revenue: Keytruda
For the past two years, Merck's Keytruda (pembrolizumab) has topped the list as the world's best-selling drug by revenue. In 2024, its global sales reached approximately $29.5 billion. Its dominance is a testament to the growth of the oncology market and the drug's widespread application in treating various cancers.
What is Keytruda?
Keytruda is a cancer immunotherapy known as a programmed cell death protein 1 (PD-1) inhibitor. It works by blocking the PD-1 protein on immune cells, essentially taking the "brakes" off the immune system and allowing it to recognize and attack cancer cells more effectively.
Why its sales are so high
- Expanded Indications: Keytruda is approved for treating over 40 indications, including non-small cell lung cancer, melanoma, and head and neck cancer, allowing it to address a vast patient population.
- High Cost: As a complex biologic treatment, Keytruda has a high price point. Its sales reflect the cost per patient as much as the number of patients treated.
- Cornerstone Therapy: It is often used as a foundational therapy in combination with other treatments, further solidifying its market position.
The Top Drug by Prescription Volume: Atorvastatin
When the metric shifts to the sheer number of prescriptions filled, the story changes dramatically. Generic medications for common conditions, which are more affordable and used by millions of people, typically hold the top spots. Atorvastatin, the generic version of the brand-name drug Lipitor, is a consistent leader in prescription volume.
Why Atorvastatin is so widely prescribed
- Treats a Common Condition: It is primarily used to treat high cholesterol, a widespread chronic condition affecting millions of people worldwide.
- Cost-Effective: As a generic drug, atorvastatin is significantly cheaper than its brand-name counterpart, making it highly accessible and a preferred choice for many healthcare systems and patients.
- Long-Term Therapy: High cholesterol requires ongoing management, leading to millions of recurring prescriptions year after year.
The Rise of Emerging Superstars: Semaglutide and Others
The pharmaceutical landscape is constantly evolving, with new therapies gaining immense popularity. In recent years, drugs like semaglutide, known by brand names Ozempic and Wegovy, have experienced explosive growth.
Key factors fueling semaglutide's rise
- Dual Applications: Semaglutide is a GLP-1 receptor agonist originally approved for type 2 diabetes (as Ozempic) and later for chronic weight management (as Wegovy).
- High Demand for Weight Loss: The significant weight-loss benefits associated with semaglutide have fueled massive demand, driving its sales past the $16 billion mark in 2024.
- High Price Point: Like other biologics, the cost of semaglutide contributes significantly to its high sales revenue, though not yet reaching Keytruda's peak.
The Former Titan: Humira
No discussion of best-selling drugs is complete without mentioning Humira (adalimumab). For many years, Humira was the world's top-selling drug by a significant margin, with peak annual sales exceeding $21 billion. It was used to treat a wide array of autoimmune and inflammatory conditions like rheumatoid arthritis and Crohn's disease.
The decline of a blockbuster
Humira's revenue has declined dramatically following the expiration of key patents, allowing numerous biosimilar competitors to enter the market. In 2024, its sales dropped to approximately $9 billion. While still a major force, this example illustrates how market exclusivity and competition shape the top ranks of the pharmaceutical industry.
Comparison of Top Prescription Drugs
| Feature | Keytruda (pembrolizumab) | Atorvastatin (Lipitor) | Semaglutide (Ozempic/Wegovy) |
|---|---|---|---|
| Primary Ranking Metric | Revenue (e.g., ~$29.5B in 2024) | Prescription Volume (e.g., >100M in 2023) | High-growth drug, now top by revenue after Keytruda |
| Primary Use | Cancer treatment | High cholesterol | Type 2 diabetes and weight loss |
| Drug Class | Immunotherapy (PD-1 inhibitor) | Statin (HMG-CoA reductase inhibitor) | GLP-1 receptor agonist |
| Formulation | Intravenous infusion | Oral tablet | Injectable pen or oral tablet |
| Price Point | Very high, complex biologic | Very low, generic | High, complex biologic |
Factors Determining a Drug's Success
- Disease Prevalence: Medications treating widespread chronic conditions like high cholesterol or diabetes will see massive prescription volumes, even if costs are low.
- Therapeutic Area: High-value therapeutic areas like oncology often command higher prices due to the complexity and life-saving potential of the treatments.
- Patent Exclusivity: The period a drug manufacturer holds a patent is crucial for its profitability. The loss of exclusivity can lead to a rapid decline in sales as cheaper generics or biosimilars flood the market.
- Innovation: Novel biologics and gene therapies, despite targeting smaller populations, can command extremely high prices due to their groundbreaking nature.
- Global Access and Market Size: The total market size a drug can penetrate globally, including factors like regulatory approvals and reimbursement policies, plays a significant role in its overall ranking.
Conclusion
The question of what is the number one prescription drug in the world reveals a multifaceted pharmaceutical landscape. For profitability, cancer drugs like Keytruda lead the charge, driven by high cost and broad use in oncology. However, when measuring by volume, common and affordable generics such as atorvastatin remain unrivaled, demonstrating their critical role in public health. Furthermore, the rapid ascent of drugs like semaglutide and the decline of former champions like Humira underscore the dynamic nature of the industry, shaped by innovation, patent expiration, and patient demand. Ultimately, a drug's success is a matter of perspective, measured by different metrics for different purposes.
For additional context on the U.S. market specifically, the Agency for Healthcare Research and Quality provides detailed data on prescription drug usage.(https://resources.healthgrades.com/right-care/patient-advocate/the-top-50-drugs-prescribed-in-the-united-states)
