10. Januvia & Janumet

Janumet
The impending loss of exclusivity for Januvia and Janumet leaves Merck in a tough spot. But with oncology superstar Keytruda carrying the company's fortunes for at least another decade, there's time for Merck to find a replacement. (Merck)

Januvia & Janumet 
Company:
Merck
2020 sales: $5.3 billion
Key patent expirations: 2022 to 2023

10. Januvia & Janumet