meta-Chlorophenylbiguanide (1-(3-chlorophenylbiguanide, m-CPBG) is an allosteric agonist and modulator of the 5-HT<sub>3</sub> receptor and an antagonist of the ñ<sub>2A</sub>-adrenergic receptor. It has anxiogenic, emetic and hypothermic effects in animal studies.