RETIRED pharmacologist Dr Richard Marshall is surprisingly laidback as he recalls how a huge overdose of the then-untested asthma drug, salbutamol, almost killed him.

It was 1968 and the 22-year-old pharmacology graduate from Falkirk was one of only three volunteers on the first ever human safety trial designed to make sure that the newly invented medication, patented two years earlier, really was ready to be trialled on patients.

Today it is ubiquitous as the blue inhaler used to relieve breathlessness in asthma sufferers.

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But the young Scot and two senior chemist colleagues employed at the tiny Hertfordshire pharmaceutical firm, Allen & Hanburys, were the original guinea pigs - given steadily increasing doses of the drug versus a control substance over three days to make sure it worked as expected.

That is, by stimulating the lungs without affecting the heart.

Not everything went to plan.

Dr Marshall, now 73, said: "I was the first person in the world to take salbutamol. That was just chance, because of where my bed was positioned during the trial.

"These were the days before health and safety - I don't think they'd be allowed to do it now. But we were supposed to be getting 2mg, 4mg and 8mg over three successive days, and they would measure blood pressure and heart rate.

"But things didn't go right on the last day because we were supposed to be getting 8mg of salbutamol but the pharmacist made a mistake in her weighing and gave us 80mg by accident.

"Alarm bells began to ring almost straight away. My heart was pounding and of course it wasn't supposed to touch the heart - but 80mg was a massive dose.

"Our blood pressure started falling away.

"That was quite hairy."

HeraldScotland: Richard Marshall in late 1968Richard Marshall in late 1968

It is hard to overestimate what a PR and financial disaster this could have been for Allen & Hanburys who had poured time and money into the race to be the first company to successfully manufacture a new type of asthma drug, known as selective beta-2-receptor agonists.

The firm, which had been taken over by Glaxo a decade earlier, was better known for medicinal pastilles and cod liver oil.

But it was another Scot - Sir David Jack, a coal miner's son from Fife - who pioneered the development of salbutamol as Allen & Hanburys director of research.

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As the overdose crisis unfolded, Sir David was telephoned at his London headquarters.

"Sir David came rushing up from Bethnal Green in his chauffeur-driven car to find out what the hell was going on," said Dr Marshall. "This was his two best chemists and a newly-recruited young Scottish pharmacologist who were now in some danger.

"He arrived - this was the first time I'd ever met him - and took charge of proceedings. When things looked a bit dodgy he decided to stop that part of the trial and gave us each a beta-blocker. That quickly reversed the side effects."

HeraldScotland: Sir David JackSir David Jack

Not one to miss the chance for some pharmacological research, however, Sir David embarked on a slightly unorthodox experiment.

"We had to collect our urine for the next three days in lemonade bottles," said Dr Marshall. "Sir David realised he's never get the opportunity again to see how quickly the body would clear a huge dose like that."

With the safety trial complete, salbutamol went on to patient clinical trials and in 1969 it revolutionised asthma treatment when it launched under the brand name Ventolin.

It proved to be a major commercial success and, 50 years on, remains the world's most used asthma drug.

"For that trial we got £30 Boots vouchers - and Sir David got his knighthood," said Dr Marshall. "But £30 was quite a lot of money then."

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The salbutamol trial was a seminal moment in both men's careers and the beginning of a friendship that lasted until Sir David's death, aged 87, in 2011.

Sir David went on to serve as Glaxo's director of research and development from 1978 until his official retirement in 1987, leading the development of Zantac to treat peptic ulcers - the first drug to generate $1 billion a year - and Zofran, for the treatment of chemotherapy-related nausea.

Dr Marshall returned to Scotland in 1971 to complete a PhD in Glasgow, followed by stints as a lecturer at Strathclyde University and a sabbatical in Canada, before being headhunted by Dutch-based pharmaceutical company Organon.

HeraldScotland: Dr Marshall at Organon in the late 1970sDr Marshall at Organon in the late 1970s

He settled in Scotstoun with his wife and two children and served as Organon's head of pharmacology and research manager in Scotland until his retirement.

Dr Marshall said: "David was very down to earth. We played golf occasionally. My wife and I had meals with Sir David and his wife.

"He still had relatives up in Cowdenbeath so when he used to visit them he would pop in to see us, and I invited him to give a couple of lectures when I was at Organon."

Now a grandfather, Dr Marshall remains proud of the contribution he and his fellow Scot made to the lives of asthma patients worldwide.

"All through my life I've met people all over the place who suddenly bring out this blue and grey inhaler and I've met people who claim it's saved their lives," said Dr Marshall. "That makes you feel like you were part of something, and that's really nice."