Green’s Dictionary of Slang

subbies n.

[abbr.]

(UK drugs) Subutex, a form of synthetic heroin.

[UK]Observer 16 Sept. 21: Subutex, like methadone, is prescribed to heroin users to help wean them off addiction. [...] The illicit market in the substance is growing exponentially. The pills – known as ‘subbies’ – are popular with prisoners.