Only days after Dr. Reddy's won a generic approval to Indivior's top drug—the opioid addiction treatment Suboxone Film—a patent spat between the drugmakers is forcing the company to halt its copycat rollout.

A U.S. court has issued a temporary restraining order against Dr. Reddy's from making further sales after the Indian generics firm launched "at risk" on Friday. Late last week, the company and Mylan both won U.S. generic nods for the Indivior med that generates hundreds of millions of dollars in sales per year. Suboxone is a sublingual film that's placed under the tongue to ease addiction cravings.

Inidivior has filed patent infringement lawsuits against both generic drugmakers, but Dr. Reddy's disclosed that it would take an "at risk" launch while its case plays out. Due to a confidential settlement Indivior inked with Mylan last year, the launch timing for that company's generic is under wraps. In a note, Bernstein analyst Ronny Gal wrote that he expects Mylan has a "standard acceleration clause" and could launch 2 to 4 weeks after Dr. Reddy's generic hits the market, if the latter company wins its patent case.

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A hearing in the case between Dr. Reddy's and Indivior is set for June 28. Indivior will have to pay Dr. Reddy's $18 million if the generics company comes up successful, Dr. Reddy's said.

In addition to that financial loss, Indivior would face the much more important loss of exclusivity for its top drug. Indivior said it expects a "rapid and material" loss of Suboxone's market share if generics hit the U.S. market. In the meantime, the company is maintaining its 2018 financial guidance until more details are clear.

RELATED: Mylan scores FDA approval of generic Suboxone for opioid addiction, but a strong launch is no sure bet

The company last week detailed its contingency plans in the event Suboxone loses exclusivity, including possible cost cuts and its own authorized generic rollout. In the long run, Indivior continues to focus on launching Sublocade, an extended-release injection for opioid addiction. Meanwhile, Indivior recently settled with Endo's Par Pharmaceutical for a 2023 generic launch date on Suboxone.

Aside from the patent dispute, Indivior is faces a Justice Department investigation over marketing, pediatric safety claims and overprescribing of its meds by some doctors. The FTC is looking into antitrust matters relating to thwarting generic competition, and 41 states have sued for alleged antitrust violations.

RELATED: Indivior's legal challenges escalate with new Suboxone subpoena from California

Earlier this year, the company boosted its provision for investigative and antitrust litigation to $438 million. At the time, Indivior said it was in discussions with the Department of Justice about a possible settlement.