Indivior also said revenue from its new opioid addiction treatment, Sublocade, would exceed the top end of its previous 2018 forecast range of $8 million to $10 million by about $2 million.
The company had cut its revenue estimate for Sublocade in September as it faced distribution challenges.
Indivior, which was spun off from consumer products group Reckitt Benckiser in 2014, said it expects to meet its full-year forecasts for net revenue of $990 million to $1.02 billion and net income of $230 million to $255 million.
The company also said it would take steps to cut administrative and research costs to boost profit.
Indivior said it would move ahead with the launch of Perseris, its injectable drug for treating schizophrenia in adults, in the United States.