Bayer AG is facing more problems related to its Yaz contraceptive, after the Federal Circuit invalidated the company’s patent on the birth control pill.

A Nevada district court Bayer’s patent, which dealt with a dosing regimen for the contraceptive, in March 2012. But, on appeal, the generic drugmakers Watson Pharmaceuticals Inc., now known as Actavis Inc.; Sandoz Inc., a unit of Novartis International AG; and Lupin Ltd. argued that the claims in Bayer’s patent were obvious and that the lower court had overlooked prior art when reaching its decision. The Federal Circuit agreed and reversed the district court’s ruling.

The patent in question was set to expire in 2014. In the wake of the Federal Circuit’s decision, Actavis announced that it would resume the sale of Vestura, its generic version of Yaz. Sandoz will also continue to ship its own generic version.

Yaz has caused quite a few headaches for Bayer, which recently set aside $1.5 billion to cover litigation expenses related to the contraceptive and its predecessor, Yasmin. Thousands of lawsuits contend that the birth control pills increase women’s risk of developing blood clots, strokes and heart attacks.

Read more at Thomson Reuters.

For more contraception-related stories on InsideCounsel, see:

Judge strikes down restrictions on “morning after” pill

Bayer seeks to block consolidation of failure-to-warn lawsuits over IUDs

Bayer settles claims of gallbladder injury caused by Yasmin and Yaz contraceptives

Bayer accused of promoting Yaz birth control for unapproved uses