A US Federal Court of Appeal (CAFC) rejected Indivior’s request for another hearing on whether its patents were infringed by a low-cost alternative developed by Dr Reddy.
A district court in Delaware had previously given the all-clear to the generic version.
The decision by the CAFC effectively ratifies that and clears the way for Dr Reddy to sell its rival in the US.
Indivior has applied for an emergency injunction to stop the Federal Court’s mandate, which comes into force on February 11.
Without that, Indivior expects both Dr Reddy and Alvogen, another generic rival, would start to market their products on that date.
Alvogen had agreed to wait until the CAFC decision on Dr Reddy.
Shaun Thaxter, Indivior’s chief executive, said he was disappointed by the CAFC’s decision.
"While we ultimately believe in the strength of our patent portfolio, we acknowledge that the company faces major disruption in the immediate future from a potential material and rapid loss of market share by our Suboxone film product to generic buprenorphine/naloxone sublingual film competition.”
Indivior will press ahead with appeals against the Delaware patent ruling and also in New Jersey against Dr Reddy and Alvogen but the former Reckitt Benckiser subsidiary has already set out contingency plans to deal with a loss of market share for Suboxone.
Measures include staff cuts, cash conservation and the launch of its own generic alternative.