Pharmaceutical company Clinigen Group said it would become a leader in the supply of unlicensed medicines to doctors and hospitals with the acquisition of Idis for £225 million.

Idis, owned by private equity group CBPE Capital, provides access to unlicensed drugs in oncology, haematology, immunology and other areas in more than 100 countries, Clinigen said.

The medicines are either approved in another market or are already in clinical trials. Doctors can offer them to patients if they think they are the most appropriate treatment.

"The unlicensed supply market is huge and it is highly unregulated," said Clinigen chief executive Peter George.

"We want clinicians and hospital pharmacists to be able to access medicine for their patients when required rather than their patients frustratingly going through their own routes."

Shares in Clinigen rose 10 per cent in early trading to 580 pence as investors welcomed the deal, which is funded in part by a £135m placing priced at 500 pence a share.

Numis analyst Charles Weston, who has a "buy" recommendation on Clinigen, said deal propelled the company to global leadership of the ethical unlicensed supply market worth about $2.2 billion whilst balancing out its portfolio.

Idis was set up in 1987 by two pharmacists in Britain looking for drugs that were not available in their home market.

Some medicines are not licensed because the manufacturer decided that it was too expensive to carry out clinical trials or, in the case of rare diseases, it was difficult to find enough patients for the trials.