13. NuvaRing

Merck's NuvaRing patent expires on April 8. (Merck on Youtube)

Company: Merck
2017 U.S. sales: $564 million
Use: Contraceptive
Patent expiration: April 8

After a 2001 approval and significant sales, Merck’s NuvaRing is coming to the end of its patent life this year. But it’s not clear whether any generic drugmakers will be able to launch when that patent expires, as two would-be copycats say they expect to introduce theirs in 2019.

Merck lost its NuvaRing patent in a 2016 court decision but appealed and won last October. Now, multiple drugmakers are preparing their versions of the vaginal contraceptive.

Mithra Pharmaceuticals has a version called Myring, and it's partnered with Mayne Pharma for the U.S. market. Mithra has previously said Myring might be able to launch in 2018, but in a recent investor presentation, Mayne itself guided for a 2019 rollout.

RELATED: India's Dr. Reddy's in $350M deal for Teva products in U.S.

Dr. Reddy’s Laboratories has a version it picked up when Teva merged with Allergan’s generics unit and was forced to divest certain assets. Actavis, which became Allergan, filed the Abbreviated New Drug Application for that med way back in 2013. On a recent conference call, Dr. Reddy’s executives said they expect a 2019 launch.

Meanwhile, United Health's unit Optum reports (PDF) that a generic launch could come in April.

The FDA has made it a goal to boost competition through generic approvals, and that trend favors generics players eyeing the market.

A Merck representative said the drugmaker generated $564 million in NuvaRing sales in the U.S. last year. The company hiked NuvaRing’s price 9.91% in January, according to a recent Wells Fargo note, a common strategy for drugmakers as important meds near the end of their patent life.

13. NuvaRing