By Justin George Varghese

(Reuters) – Indivior shares fell more than 20 percent after the British drugmaker warned of a bigger-than-expected blow from a copycat of its top opioid addiction treatment and posted weak initial sales from its new blockbuster prospect.

The company, which reported a second straight drop in quarterly profit on Wednesday, said “uncertainties” stopped it from issuing guidance weeks after scrapping its full-year forecast amid market share loss to an Indian copycat rival.

Indivior’s shares have dropped more than 40 percent since India’s Dr.Reddy’s Laboratories announced a cheaper version of the UK firm’s blockbuster opiate addiction drug Suboxone Film.

The impact on revenue from the copycat “could be materially higher” than the $25 million forecast earlier this month, the company said. Jefferies analysts estimate the hit will be $37.5 million to $45 million for the year.

A U.S. court blocked Dr.Reddy’s from selling a cut-price version of Suboxone Film on July 13, but not before the drug’s market share dropped rapidly. Its share stands at 49 percent from 52 percent before it won the injunction.

NEW DRUG WORRIES

Investors were also disappointed with lower-than-expected sales from the firm’s new opioid addiction drug Sublocade.

Instead of going to the pharmacy to pick up tablets or an under-the-tongue film, Sublocade injections are delivered direct to doctors for administration.

Indivior has pinned its hopes on the once-monthly injection it launched in February, but the company said it was experiencing “some friction” in the new distribution and reimbursement model for Sublocade, making doctors less willing to prescribe the new drug.

Sublocade revenues in the first half were $2 million, below brokerage Jefferies’ expectations but the company said it hopes revenue from the drug will be in the range of $25 to $50 million for the year.

Sublocade’s prescription journey – the time from prescription to injection – has been slow, but the company has lowered it from 43-62 days at launch to 27-36 days currently and Chief Executive Shaun Thaxter said he hopes to get that down to 15-18 days.

Thaxter said the company was making “good” progress in overcoming Sublocade’s initial challenges and remains confident that Sublocade will deliver peak net revenue of more than $1 billion a year.

Adjusted net income fell 21.3 percent to $70 million in the quarter ended June 30 from a year earlier, while revenue fell 6.9 percent to $268 million in the quarter.

(Reporting by Justin George Varghese in Bengaluru; Editing by Jane Merriman and Elaine Hardcastle)