There's an important point here that's often overlooked. Drugs themselves can serve as currency, but just like salt in Rome, such currencies are consumer goods as well as fungible commodities. Their consumability as well as their growth/collection time form a natural barrier against inflation.

Of course such currencies are economically inefficient. But I think too much monetary efficiency is bad, because it encourages financialization and excess risk. for generations now we have been borrowing from our descendants to pay for things in the present, seeming to come out ahead on paper but more often than not running up a hideous and poorly-accounted-for environmental bill while establishing a consumption-based economy that promotes waste. I've long wondered if we shouldn't treat oil as a de facto currency rather than only as a commodity.