8. AbbVie

AbbVie is looking at a much different future if its $63 billion with Allergan closes in mid-2020, likely making the new company the fourth-largest drugmaker in the world. (AbbVie)

2019 revenue: $33.27 billion
2018 revenue: $32.75 billion
Headquarters: North Chicago, Illinois

For the first time in many years, AbbVie's blockbuster immunology med Humira showed some cracks as biosimilar challengers rushed the European market in 2019. But for AbbVie––with an Allergan megamerger in the works and two exciting new launches––the future looks bright even with its sales workhorse losing steam.

AbbVie hit $33.27 billion in net revenue in 2019 on the back of mostly stable sales for Humira and boosts from blood cancer meds Imbruvica and Venclexta.

Still, the story of 2019 for AbbVie was the arrival of European copycats for Humira, which sent sales of the megablockbuster plummeting in the back half of the year.

RELATED: AbbVie touts Humira defense strategy abroad as a positive sign for forthcoming U.S. battle

8. AbbVie