Synthetic cathinones, colloquially referred to as “bath salts,” are derivatives of the psychoactive alkaloid cathinone found in Catha edulis (Khat). Since the mid-to-late 2000s, these amphetamine-like psychostimulants have gained popularity amongst drug users due to their potency, low cost, ease of procurement, and constantly evolving chemical structures. Concomitant with their increased use is the emergence of a growing collection of case reports of bizarre and dangerous behaviors, toxicity to numerous organ systems, and death. However, scientific information regarding the abuse liability of these drugs has been relatively slower to materialize. Recently we have published several studies demonstrating that laboratory rodents will readily self-administer the “first generation” synthetic cathinones methylenedioxypyrovalerone (MDPV) and methylone via the intravenous route, in patterns similar to those of methamphetamine. Under progressive ratio schedules of reinforcement, the rank order of reinforcing efficacy of these compounds is MDPV ≥ methamphetamine > methylone. MDPV and methylone, as well as the “second generation” synthetic cathinones α-pyrrolidinovalerophenone (α-PVP) and 4-methylethcathinone (4-MEC), also dose-dependently increase brain reward function. Collectively, these findings indicate that synthetic cathinones have a high abuse and addiction potential and underscore the need for future assessment of the extent and duration of neurotoxicity induced by these emerging drugs of abuse. 1. The Rise of Synthetic Cathinone Use and Abuse In 2007, a new class of designer drugs known as synthetic cathinones emerged in Europe. Soon afterwards, reports of synthetic cathinone use, abuse, toxicity, and death began to surface in USA [1–12]. The rise of synthetic cathinone use in USA was alarmingly rapid, with poison control centers receiving 0, 304, and 6156 calls reporting synthetic cathinone toxicity in the years 2009–2011, respectively [13]. Approximately 98% of synthetic cathinones first identified in toxicological investigations were primarily 4-methylmethcathinone (4-MMC, mephedrone), 3,4-methylenedioxypyrovalerone (MDPV), and 3,4-methylenedioxymethcathinone (methylone) [1–12], but as discussed below, many additional synthetic cathinones have since surfaced. Synthetic cathinones are chemical derivatives of cathinone, a naturally occurring amphetamine-like alkaloid found in the Catha edulis (Khat) shrub. Khat has been utilized for centuries by indigenous peoples of the Horn of Africa and Arabian Peninsula for its stimulant properties [14]. However,
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