Green’s Dictionary of Slang

coker n.2

[coke n.1 (1) + sfx -er]

(US) a cocaine user.

1998
1998199920002001200220032004
2005
[US](con. 1986) G. Pelecanos Sweet Forever 105: Hundreds of other cokers across the city were sleeping off their friday night grams.
[US]J. Stahl I, Fatty 217: I’d have liked to [...] hear what the old coker [i.e. Freud] had to say.