The Scottish Executive has been accused of concentrating on tackling drug abuse through the justice system rather than investing in rehabilitation services.
Ministers said they were exploring a range of options
Former deputy justice minister Richard Simpson said spending was "skewed" towards long-term addicts and should be targeted at those in the early stages.
He spoke out after ministers admitted they did not know how many people were receiving heroin substitute methadone.
The executive said it was exploring all forms of treatment.
A spokesman said prescription statistics did not give the precise information on the numbers taking methadone, although the figure was estimated at 19,200 last year.
Statistics for the number of people who have come off methadone to become completely drug-free were also unavailable.
David Liddell, director of the Scottish Drugs Forum, said there needed to be a range of measures in place to help move people off methadone.
He suggested education and training programmes to give addicts hope that there was life beyond drug dependency.
Dr Simpson, who resigned as a deputy minister in 2002, said the executive was concentrating too much effort on the criminal justice element of drug abuse.
He said drug courts were the most expensive measure, although it was not yet known if they were successful.
"Then there are drug treatment and testing orders, and below that there are a number of other orders which are all on the criminal end of things," he said.
"They are highly intensive, very costly, and they impinge on the most difficult addicts.
"We should be spending more funds and more attention on those at the other end of the spectrum who have recently become dependent, those who have children, for example, but are not involved in substantial criminal activity.
"I think we have got our expenditure somewhat skewed."
The executive said it was expanding all types of treatment, not just methadone.
"Services must work together to address the often complex factors which can underpin addictions," said a spokesman.
"Methadone is not a solution to drug addiction. But as part of a programme it allows people to stabilise their lives enough to think about the next stage in the journey away from drugs, and towards a much more positive life.
"It is high time we ended the unhelpful obsession in trying to prove whether abstinence or harm reduction strategies are best. The most effective treatment will always depend on the circumstances of the individual addict - there is no 'one size fits all' solution."