14. Ampyra

Acorda Therapeutics lost an Ampyra patent case last year, leading the company to lay off staff. (Acorda on Twitter)

Company: Acorda Therapeutics
2017 U.S. sales: $543 million
Disease: Multiple sclerosis
Patent expiration: July 30

While it doesn’t generate as much in sales as the drugs that lead this list, Ampyra’s $543 million haul last year was critical for small biotech Acorda. After a patent decision felled Ampyra's intellectual property in April last year, the company has had to cut costs through layoffs.

With that patent decision—which Acorda is appealing—the company loses its Ampyra patent protections in July. On Acorda’s fourth-quarter conference call, CEO Ron Cohen said the company will request an injunction to prevent generic launches if it doesn’t have a decision on its appeal by then.

RELATED: Court nixes Acorda patents, teeing up Ampyra generics—and potential cost cuts, analyst says

Acorda last year announced a plan to cut about 20% of its workforce, or more than 100 jobs, to prep for the impending patent loss and sales downfall.

Looking ahead, the company is hoping its drug candidate Inbrija can make up for lost sales from Ampyra. The Parkinson’s prospect is under FDA review and could pull in $800 million in peak U.S. sales, Acorda said early this year.

The Ampyra court decision wasn’t the only piece of bad news for the drugmaker last year, however. In November, the company scrapped phase 3 candidate tozadenant to treat Parkinson’s disease after patients died in clinical testing.

Biogen sells Acorda’s Ampyra outside of the U.S. as Fampyra.

14. Ampyra