m-Chlorophenylbiguanide hydrochloride is a 5-HT3 receptor agonist. m-Chlorophenylbiguanide hydrochloride selectively binds 5-HT3(Ki: 0.002 uM) over 5-HT1A(Ki: 10 uM) and 5-HT2(Ki: 10 uM) receptors but also binds to high and low affinity sites on the dopamine transporter(DAT; IC50s: 0.4 and 34.8 uM, respectively, in rat caudate putamen synaptosomal membranes).