(Reuters) - Indivior Plc (L:INDV) reported a 19% slump in third-quarter revenue on Thursday as the British drugmaker's best-selling opioid addiction treatment lost more than half of its market share to cheaper generic rivals in the United States.
The company's shares were down 6.5% after profit also fell by double-digits percentage. The stock has lost nearly two-thirds of its value this year as the London-listed firm faces competition from copycat drugs as well as a $3 billion (£2.3 billion) U.S. fine for illegal marketing practices related to Suboxone.
The company, which gets the bulk of its sales from the United States, had gained from the government's stepped up efforts to combat an opioid epidemic.
Indivior has said it will "vigorously defend itself" against the U.S. charges, adding that even if it is unable to reach a settlement, the indictment is not likely to hit operations over the next 12 months.
The company backed its annual revenue and profit forecasts from earlier this month, when it had raised them on a slower-than-expected erosion in Suboxone's market share.
The market share for its branded Suboxone Film fell to 26% at the end of the third-quarter from 52% a year ago.
Revenue fell to $199 million in the three months ended Sept. 30, from $245 million a year earlier, with operating profit also falling 20%.