FOURPHIT is a derivative of phenylpiperidine with an isothiocyanate substituent at the 4-position of the piperidine ring. This compound can inhibit the binding of [3H]-methylamphetamine to the binding sites on the dopamine transport complex. FOURPHIT may serve as a relatively selective affinity label for sites on the dopamine transport complex recognized by methylamphetamine and other psychomotor stimulants.