In the three months to 30 September, total net revenue decreased 19% to US$199mln, net income plunged 46% to US$48mln and earnings per share were down 42% to 7.0 cents.
The UK and US-based company, which faces a possible US$3bn fine from ongoing court proceedings over alleged illegal marketing practices related to Suboxone, said in a statement that the flagship anti-opioid suffered from the introduction of generic competitors in the market in February.
Full-year guidance, which was revised up earlier this month, was maintained despite these declines.
Earlier this month, the firm announced it would stop producing its own generic product containing the same active principles as Suboxone, which is said was to mitigate the financial risks from a change in US government calculation for generic drug pricing.
For the full year, the company expects to generate net revenue between US$750mln-US$790mln and net income of US$160mln-US$190mln.
Chief executive Shaun Thaxter said in the statement that the company believes the new US legislation would have resulted in the “unsustainable position of Indivior selling SUBOXONE Film at a negative gross profit through most US government channels”.
On the court case he said it was difficult to predict the impact of the lawsuit on its balance sheet but added that the company “believes it has strong defences to the government’s charges and will vigorously defend itself”.
Indivior shares were down 10% to 40.93p on Thursday afternoon.