(Reuters) - A U.S. appeals court on Tuesday allowed generic drug company Dr. Reddy’s Laboratories to sell a copycat version of the Indivior Plc opioid treatment Suboxone Film, sending Indivior’s stock price down more than 40 percent.

The U.S. Court of Appeals for the Federal Circuit lifted a preliminary injunction that blocked Dr. Reddy’s from selling the generic, saying a lower court judge erred in granting the request.

Indivior said in a statement that it would continue to vigorously pursue ongoing U.S. patent litigation against Dr. Reddy’s that seeks to block sales of the generic version.

Suboxone Film generates 80 percent of UK-based Indivior’s revenue and helps drug users beat their addiction to opioids and is dissolved under the tongue.

Indivior, spun off from consumer products group Reckitt Benckiser in 2014, said in June it would consider selling its own generic product if Dr. Reddy’s launched a copycat version.

Indivior’s contingency plans also focus on optimizing the launch of Sublocade, a once-a-month injectable drug to suppress opioid craving, launched in the United States in February.

Hyderabad, India-based Dr. Reddy’s did not immediately respond to a request for comment.