Deprenyl, also known by its developmental code name E-250 and as N-propargylmethamphetamine, is the racemic mixture of D-deprenyl and L-deprenyl (selegiline).

[1][2][3] It was discovered in 1961 in Hungary at Chinoin Pharmaceutical Company by Zoltan Ecseri and József Knoll, was patented in 1962, and was first described in the literature in 1964 or 1965.

[1] The dextrorotatory isomer, D-deprenyl, was found to be more toxic, producing effects like hyperthermia and more potent psychostimulation in rodents.

[1][2] The levorotatory isomer, selegiline, was much more potent as an MAO-B inhibitor, and was subsequently developed for the treatment of Parkinson's disease and depression.

[2][3] Deprenyl is reported to result in side effects including agitation, anxiety, and sleep disturbances more often than selegiline.