3-Methylmethcathinone (3-MMC), also known as metaphedrone,[4] is a designer drug from the substituted cathinone family. 3-MMC is a monoamine transporter substrate (a substance acted upon by monoamine transporters in the brain) that potently releases and inhibits the reuptake of dopamine and norepinephrine, as well as displaying moderate serotonin releasing activity.[5][6] 3-Methylmethcathinone is a structural isomer of mephedrone (4-methylmethcathinone), and as such is illegal via blanket bans in many countries that have banned mephedrone. However, 3-MMC has still appeared on the recreational drug market as an alternative to mephedrone, and was first identified being sold in Sweden in 2012.[7] Unlike some other synthetic cathinones, 3-MMC has been evaluated in at least one large mammal study.[2]