Scotland Against Drugs was set up in 1996 and trained more than 3,500 primary teachers over the ensuing five years, running refresher courses thereafter.
Teachers were also trained in every secondary school and, most recently, the agency has been piloting training courses for pre-five staff in Stirling, Falkirk and Clackmannanshire.
Its demise at the end of March, to be absorbed into the new Scottish Centre for Healthy Working Lives, part of the National Health Service, will inevitably raise concerns about whether its work will continue.
"Scotland has led the way in drugs education for 20 years," Alistair Ramsay, director of the agency, told The TESS.
This development comes when the need for work to support teachers was dramatically highlighted with the news of the 11-year-old girl in a Glasgow east end primary who collapsed and had to be taken to hospital after smoking heroin, which she admitted to doctors she had been doing for more than two months.
Mr Ramsay called for calm. "We must maintain a sense of perspective on what schools can reasonably do," he said. "This case, while disturbing, is unusual and likely to be an isolated incident."
He added: "We've got to remember that pupils spend only one ninth of their lives in schools from the ages of five to 16. Who picks up on what they are doing the other eight-ninths of the time?"
Studies carried out by Neil McKeganey and colleagues at Glasgow University's Centre for Drug Misuse Research, reported in 2004, concluded that around 60 children in the 10-12 age group will have used heroin in Glasgow. Based on work among pre-teens in the city and in Newcastle, the study found that 30 per cent of young children had been exposed to illegal drugs and 3.9 per cent had started to use them.
The decision by the executive to transfer SAD to the Scottish Centre for Healthy Working Lives, announced in December, reflects a switch in priorities. Hugh Henry, the Deputy Justice Minister, said there was a need to tackle "the wider problems that many serious drugs misusers face in making the transition from addiction to healthy fulfilling lives".
It remains to be seen whether this emphasis on employability rather than education will affect the level of support which schools have been receiving for the past decade.