NHS Tayside has shaved 40% off its methadone spending by dumping a named brand in favour of a more generic drug.
A nationwide move to switch suppliers a few years ago helped the healthboard make savings of £213,055 between 2011/12 and 2015/16.
The painkiller is used to treat heroin addiction, and 2,287 patients were given a prescription for it in 2015/16.
Almost 44,000 litres were used by NHS Tayside in 12 months, a similar figure to previous years.
However, the overall cost has dropped by 42.5% since 2011/12, despite slightly more of the painkiller being used.
It is understood the previous supplier was dropped and replaced with a cheaper alternative.
Methadone is offered to help reduce withdrawal symptoms for patients addicted to heroin, producing similar effects to the Class A substance.
The synthetic opiate also acts as a painkiller, depressing the nervous system and reducing physical and psychological pain.
A patient who is addicted to heroin will often be prescribed methadone to take instead of heroin and the dose of methadone is gradually reduced over time. This means that the patient can give up heroin avoiding acute withdrawal symptoms.
An NHS Tayside spokesperson said: “The number of people prescribed methadone and the volume prescribed has remained relatively stable over the period.
“The annual cost for supplying methadone has reduced over the last few years as a result of changes to the drug tariff across Scotland.”
Last year, Scotland’s methadone programme was described as “out of control by an expert.
Dr Neil McKeganey, of the Centre for Drug Misuse Research, said: “It is literally a black hole into which people are disappearing.”
A lack of data to measure the programme’s impact was the focus of criticism from Dr McKeganey.
He said: “We still don’t know how many addicts are on the methadone programme, what progress they’re making, and with what frequency they are managing to come off methadone.
“Successive inquiries have shown that the programme is in a sense out of control; it just sits there, delivering more methadone to more addicts, year in year out, with very little sense of the progress those individuals are making towards their recovery.”