Green’s Dictionary of Slang

(drugs) heroin.

2002		DRUG-ARM Aus. 🌐 Slang Terms: dragon Heroin.
2013		K. Sampson Killing Pool 153: Heroin was my fist taste of action [...] in ’84, and here I am back in the saddle and out on the trail of the dragon once again.
2013		J. POrter ‘One More Day Can’t Hurt’ in ThugLit Apr. [ebook] Drink and the dragon pulled him down.