Pfizer has lost a long-running court battle in the UK after the country’s Supreme Court ruled against the drugmaker in a case relating to Lyrica (pregabalin), which was originally developed as a treatment for epilepsy but has been more recently used to help patients suffering from neuropathic pain.

The ruling has backed a decision by the Court of Appeal in October 2016 when it affirmed a High Court decision that the patent claims relating to pain were invalid and had not been infringed by generic versions.

Though the company’s original patent expired in 2014, Pfizer had secured a second-use patent as a pain treatment until 2017. The company has been arguing that generic alternatives made by companies such as Allergan and Mylan would inevitably also be used to treat pain and would therefore infringe its patent.

The Supreme Court ruled, however, that the secondary patent relating to neuropathic pain is not valid, which could open the door for the UK’s National Health Service (NHS) to seek to recover the extra costs it incurred from using Pfizer’s more expensive Lyrica instead of cheaper generic versions.

Speaking to Reuters news agency, Darren Smyth, partner at low firm EIP, said:  “This is an enormous blow to Pfizer. They face claims running potentially into hundreds of millions of pounds if the NHS seeks to recover the excess costs.” Media reports said the NHS claim could amount to more than £500 million.

Pfizer has voiced its disappointment with the decision, saying the ruling “has significant import on innovation in public health.” The drugmaker commented: “The period that a medicine is under patent is a critical phase in its lifecycle that fuels innovation – as science evolves and knowledge grows, patients increasingly benefit from ongoing research into new uses for existing medicines. As situations such as these are expected to become more common, it’s important for patients that pharmaceutical companies are able to protect patents, including second medical use patents.”

In August 2018, Pfizer submitted an application to the US Food and Drug Administration (FDA) seeking pediatric exclusivity for Lyrica with a decision expected by Dec. 30. If granted, it would extend Lyrica’s period of exclusivity in the US by another six months to Jun. 30, 2019.