<P> Due to the relative safety of MDMA, some researchers such as David Nutt have criticized the scheduling level, writing a satirical article finding MDMA to be 28 times less dangerous than horseriding, a condition he termed "equasy" or "Equine Addiction Syndrome". </P> <P> Methylenedioxypyrovalerone (MDPV) is a psychoactive drug with stimulant properties that acts as a norepinephrine - dopamine reuptake inhibitor (NDRI). It was first developed in the 1960s by a team at Boehringer Ingelheim . MDPV remained an obscure stimulant until around 2004, when it was reported to be sold as a designer drug . Products labeled as bath salts containing MDPV were previously sold as recreational drugs in gas stations and convenience stores in the United States, similar to the marketing for Spice and K2 as incense . </P> <P> Incidents of psychological and physical harm have been attributed to MDPV use . </P> <P> Mephedrone is a synthetic stimulant drug of the amphetamine and cathinone classes . Slang names include drone and MCAT . It is reported to be manufactured in China and is chemically similar to the cathinone compounds found in the khat plant of eastern Africa . It comes in the form of tablets or a powder, which users can swallow, snort, or inject, producing similar effects to MDMA, amphetamines, and cocaine . </P>

Which of the following is a type of stimulant drug