M Kat is a nickname for Mephedrone, also known as 4-methylmethcathinone (4-MMC), is a stimulant and entactogen drug of the phenethylamine, amphetamine, and cathinone chemical classes.
Mephedrone is reported as causing effects described as a cross between those of methamphetamine and MDMA ("Ecstasy"), producing euphoria, stimulation, and empathy. It generally sells for a higher price than MDMA but is cheap to produce meaning that manufacturers are making "huge amounts of money" from selling the drug
