Are MDPV OR mephedrone piperazines?
Definitely not, both are substituted cathinones, as is flephedrone. However MDVP has a pharmacological profile that is nearly identical to several piperidines (not to be confused with piperazines) such as m/ethylphenidate and desoxypipradrol. It is about 4x times stronger than the former but still considerably weaker than the latter which is one of the strongest stimulants in existence, on a mg basis: 500mg lasts me a whole month of daily (ab)use despite my being stimulant tolerant. Might sound cheap but one must include the cost of downers required to deal with side effects: phenazepam, etaqualone or chloral hydrate. I recommend having those handy for MDVP as well.
To address the topic of this thread, Flephedrone is 4-FMC, the original confusion over which one of 3-FMC or 4-FMC is the official bearer of the name has dissipated since the time this thread was originally posted. This substance is now difficult to find due to bans in many countries but still easy to legally obtain in Canada (as with most RC's) but unfortunately Canadian suppliers won't ship it to the US, just like most of the serious goodies they have in stock. Unlike most other substituted cathinones Flephedrone is a straight stimulant with very little deleriant or entactogen properties, that's why most 'drones' users care little for it. But those who like stims like cocaine, amphetamines or m/ethylphenidate will appreciate it if they have no other choice, because it is quite more costly than other RC straight stims like ethylphenidate or desoxypipradrol. On the other hand, its side effects are a lot less bothersome which is the reason why many users stick with it.
MDVP also belong to this category but is now banned even in Canada due to too many incidences of fatal OD's, which is the main criteria for a ban here where authorities are otherwise rather tolerant. Like I already mentioned MDVP has very similar effects than m/ethylphenidate and their derivatives, pharmaceutical amphetamines, cocaine, and desoxypipradrol. Its toxicity was a serious problem though, at equipotent dosage side effects were more pronounced than those of other similar drugs. The very opposite of flephedrone even though both are substituted cathinones.
Mephedrone is also a substituted cathinone but ublike MDVP and Flephedrone it is not a straight stimulant because it has entactogen and deleriant properties. That is the reason why people who like MDMA like it, and why those that don't like MDMA stay away from it. Mephedrone is a party drug (like alcohol), while straight stims are performance drugs (like energy drinks).
I hope this covers it.