Is that gone as part of some stupid war on drugs or other?
From https://www.nhs.uk/live-well/healthy-body/drug-addiction-get...:
> If you're dependent on heroin or another opioid drug, you may be offered a substitute drug, such as methadone.
https://www.independent.co.uk/news/uk/home-news/heroin-addic...
It's also used legally in the UK in paliative care for cases where it's easier to administer than morphine.