Question: What synthetic stimulant is sometimes called flaka or gravel?
Sentence (from "Alpha-Pyrrolidinopentiophenone"): α-Pyrrolidinopentiophenone (also known as α-pyrrolidinovalerophenone, α-PVP, O-2387, β-keto-prolintane, Prolintanone, or Desmethyl Pyrovalerone) is a synthetic stimulant of the cathinone class developed in the 1960s that has been sold as a designer drug.
Relevant evidence: No