MDPV

# Overview
Methylenedioxypyrovalerone, also known as MDPK or 1-(3,4-methylenedioxyphenyl)-2-pyrrolidinyl-pentan-1-one, is a stimulant drug which acts as a norepinephrine and dopamine reuptake inhibitor, reportedly with four times the potency of methylphenidate.  This compound is reported to be used as a stimulant and an aphrodisiac. It has no history of medical use but has been sold as a "research chemical" (a.k.a. designer drug) for recreational use.

# Appearance and effects
The substance appears as an off-white to light-brown crumbly powder that is significantly hydrophilic, at least as has been available from the few online sellers who offered it.  It appears to darken slightly in colour and take on a potato-tuber-like odor if exposed to air for any significant length of time.  Early on, an impurity was identified and said to consist of pyrrolidine, and that could account for its earthy odour when left uncapped.  It has also been observed to rapidly degrade and lose potency when in solution.
Subjective effects include CNS stimulation, euphoria, hypersexuality, agitation/anxiety and insomnia, with a duration of three to six hours.  High doses have been observed to cause intense, prolonged anxiety attacks in stimulant-intolerant users, and there are anecdotal reports of addiction at higher doses or more frequent dosing intervals. MDPV has been remarked about more than once for its powers as an aphrodisiac, which have been said to rival those of methamphetamine when dosed correctly .  However, it is apparently not as powerful as meth as far as general effects go, and may be safer (there have been no reports of death or disability as a result of abuse posted on "research chemical" related internet forums, and these tend to surface rapidly when a substance poses immediate dangers).
MDPV is the 3,4-methylenedioxy ring-substituted analogue of the appetite suppressant pyrovalerone, however despite its apparent structural similarity to the untrained eye, the effects of MDPV bear little resemblance to other methylenedioxyphenylalkylamine derivatives such as MDMA and methylone, instead producing purely stimulant effects with no empathogenic qualities.  Extended binges on MDPV have also been reported to produce severe come-down syndrome similar to that of methamphetamine and characterised by depression, lethargy and headache.   

# Legality
MDPV is not specifically listed as an illegal drug in any country, but its structural similarity to illegal drugs of abuse makes it likely that it would be considered a controlled substance analogue in several countries such as the USA, Australia and New Zealand. Other analogues derived from alpha-pyrrolidinopropiophenone include the 4-methyl analogue pyrovalerone, as well as analogues with no substitution on the aromatic ring, and analogues with between 3 and 6 carbons on the alkyl chain. 
These compounds have been reported as stimulants of abuse mainly in Germany and other european countries since the early 2000s, but they have remained little known and rarely used or encountered by law enforcement.   MDPV was never sold online in large quantities, and as of October, 2007 has become virtually unobtainable.