Let’s start by comparing some old-school drugs, cannabis and cocaine, and their relative occurrence on web pages containing the numbers 2004 to 2010. In other words, let’s see how their web-popularity has changed in recent years:
They are almost identical. Let’s try another two, MDMA and heroin:
Again they are very similar, but with a slight tailing off for MDMA (harder to make in the UK since 2008).
Now let’s try mephedrone and cocaine. The difference is massive.
Meanwhile, it is almost completely absent from the medical literature.