The maker of drugs that treat opioid addiction raised its full-year revenue forecast to a range of $1.09 billion to $1.12 billion, from its previous guidance of $1.05 billion to $1.08 billion.

The company also said it expected adjusted net income of $265 million to $285 million, above its previous range of $200 million to $220 million.

Indivior's shares were up 12.1 percent at 355.6 pence as of 0842 GMT, after the company reported a 4-percent increase in revenue for the first half, driven by higher sales in the United States of an oral version of a drug used to treat patients addicted to heroin and other painkillers.

Revenue rose to $553 million for the six months ended June 30, from $531 million a year ago.

Operating profit was up at $244 million, from $198 million a year earlier.

Sales of Suboxone Film, the dissolvable oral strip form of the anti-addiction drug, were higher in the reporting period, although its market share fell slightly from a year ago, hurt by competition from generic versions.

In the United States, its biggest market, growth was also driven by a regulatory change to allow qualified physicians to treat up to 275 patients from 100 patients at a time.

The company said its research and development expenses fell by 32 percent to $19 million in the second quarter, while it also recorded a $25 million one-time charge to settle an antitrust litigation with Amneal Pharmaceuticals LLC.

Last year, the company incurred legal costs of $220 million to defend itself in lawsuits, hurting profits.

(Reporting by Justin George Varghese in Bengaluru; Editing by Biju Dwarakanath)