Spiramide

Spiramide (AMI-193) is a potent and selective antagonist of 5-HT₂ and dopamine D2 receptor, with K_is of 2 nM and 3 nM, respectively. Spiramide has >2000-fold selectivity for 5-HT₂ versus 5-HT_1C (K_i=4300 nM) receptors. Spiramide exhibits antipsychotic activity^[1][2][3]. In Vitro: Spiramide retains affinity for 5-HT_1A sites (K_i=50 nM) and also binds at dopamine D2 sites (K_i=3 nM), but possesses low affinity for dopamine D1 sites (K_i=2530 nM)^[1]. In Vivo: AMI-193 (0.003-0.01 mg/kg; i.m.) dose-dependently decreases response rate in monkeys under a fixed-interval (FI) schedule of stimulus termination^[2].
AMI-193 (0.003-0.01 mg/kg; i.m.) attenuates the discriminative-stimulus effects of cocaine in drug-discrimination experiments^[2].
AMI-193 (0.003-0.01 mg/kg; i.m.) reduces response rate under a second-order schedule of i.v. self-administration of cocaine (0.1 mg/infusion)^[2].