Wildly guessing here but, a country recently industrialised and massively corrupt with it, an urban population growing in cash and unmet expectation, how can party drugs not be a thing. Meth, K, and X, yo.
I recall reading something about heroin being a poor man's drug in China because no one had the wit to organize distribution into the cities. (I read this in the context of a report on prostitution in China: in ze long ago, hooking was for a time a chosen profession, with young women seeing it as an upward mobility tool, a way out of the poor places; and that such prostitution was less associated with intravenous drug use and HIV than usual because among other things, the drug fiends tended to be poor men who stayed in the poor places; but that this was changing.) Therefore, [insert hand waving here], party drugs.