I haven't watched the film and documentary series about the USA problems with addiction to common painkiller medications, but I know they exist (and I do intend to get round to it when I can handle some grim watching).
I caught a few minutes of Jamie Lee Curtis talking about her Oxycontin addiction and I think Matthew Perry was also addicted before getting into ketamine (?). So I can understand it and get a handle on it - what would be the equivalent drugs in the UK?