Thioridazine-d3 is intended for use as an internal standard for the quantification of thioridazine (Item No. 14400) by GC- or LC-MS. Thioridazine is a typical antipsychotic.{24253} It binds to dopamine D2, histamine H1, M3 muscarinic, and a1- and a2-adrenergic receptors (Kis = 5-341.3 nM), as well as the serotonin (5-HT) receptor subtypes 5-HT1A, 5-HT2A, 5-HT2C, 5-HT6, and 5-HT7 (Kis = 10-180.7 nM). Thioridazine (5 mg/kg) reduces amphetamine-induced repetitive head bobbing and oral behavior in rats.{46837} It reduces conditioned fear stress-induced freezing behavior in rats when administered at doses ranging from 3 to 100 mg/kg.{46838} Thioridazine is also active against multidrug-resistant tuberculosis in vitro and in vivo.{46839}