Metabolism and disposition of N-(2-cyanoethyl)amphetamine (fenproporex) and amphetamine: study in the rat brain.

N-(2-Cyanoethyl)amphetamine (fenproporex, CE-AM) is a clinically used anorexiant claimed to be devoid of the stimulant properties associated with amphetamine (AM). This claim was inconsistent with preliminary studies conducted in our laboratories which indicated that CE-AM is metabolically dealkylated to AM to a considerable extent in the rat. Concentration-time profiles of CE-AM and its metabolites AM and 4-hydroxyamphetamine (4-OH-AM) in the rat brain were constructed after administration of CE-AM. Analyses of CE-AM, AM, and 4-OH-AM were performed by gas chromatography with electron-capture detection using pentafluorobenzoyl chloride (under aqueous conditions) as the derivatizing reagent. The half-life (t1/2) and the maximum concentration (Cmax) of AM after administration of CE-AM were calculated to be 2.04 and 0.56 times the respective t1/2 and Cmax obtained after an equimolar dose of AM. Significant differences in the profiles of 4-OH-AM were also observed. The Cmax of 4-OH-AM in rat brain after administration of CE-AM was nearly 4 times higher and the tmax (time at which concentration is maximum) 4 times lower than the respective Cmax and tmax values of 4-OH-AM observed after an equimolar dose of AM.