Professor Robert Stockley is leading the UK trials

The drug, which has not yet been given a name, is being tested on 50 patients in Birmingham, most of whom have emphysema, as part of a UK-wide study.

The 12-month test is being led by a team of scientists from Birmingham's University Hospital.

The drug works by stimulating a lung into growing again, repairing damage and helping it to function normally.

Professor Robert Stockley of University Hospital said 20% of people admitted into hospital suffered from some sort of breathlessness, caused by emphysema or other chronic lung conditions.

30-year wait

"A lot of people have been working on this since the mid-1970s," he said.

"We came to realise this was a big problem with no specific treatment."

This is quite exciting Prof Robert Stockley

The new drug came about when scientists made a study of what makes babies' lungs grow when in the womb.

"They discovered an extract of vitamin A was used in the process and started to wonder if this would help correct lungs affected by emphysema," said Prof Stockley.

Tests on animals proved successful so a drug was devised which would work on the lungs' receptors.

The hospital scientists have also devised new ways of measuring emphysema and its progress which is being used in conjunction with the drug tests.

"This is quite exciting. We always think what it would be like to find a new treatment. This is 30 years later and we are having the first definitive trial," Prof Stockley added.