SB-616234-A

SB-616234-A is a selective and orally bioavailable 5-HT1B receptor antagonist, with anxiolytic and antidepressant activity. In Vitro: SB-616234-A possesses high affinity for human 5-HT1B receptors stably expressed in Chinese hamster ovary (CHO) cells (pK_i 8.3 ± 0.2), and is over 100-fold selective for a range of molecular targets except h5-HT1D receptors (pK_i 6.6 ± 0.1). Similarly, affinity (pK_i) for rat and guinea pig striatal 5-HT1B receptors is 9.2 ± 0.1. In [³⁵S]-GTPγS binding studies in the human recombinant cell line, SB-616234-A acts as a high affinity antagonist with a pA₂ value of 8.6 ± 0.2 whilst providing no evidence of agonist activity in this system. In [³⁵S]-GTPγS binding studies in rat striatal membranes, SB-616234-A acts as a high affinity antagonist with an apparent pK_B of 8.4 ± 0.5, again whilst providing no evidence of agonist activity in this system. SB-616234-A (1 μM) potentiates electrically stimulated [³H]-5-HT release from guinea pig and rat cortical slices (S2/S1 ratios of 1.8 and 1.6, respectively)^[2]. In Vivo: SB-616234-A reverses the 5-HT1/7 receptor agonist, SKF-99101H-induced hypothermia in guinea pigs in a dose related manner with an ED₅₀ of 2.4 mg/kg p.o. SB-616234-A produces dose-related anxiolytic effects in both rat and guinea pig maternal separation-induced vocalisation models with an ED₅₀ of 1.0 and 3.3 mg/kg i.p., respectively^[1]. SB-616234-A (0.3-30 mg/kg p.o.) causes a dose-dependent inhibition of ex vivo [³H]-GR125743 binding to rat striatal 5-HT1B receptors with an ED₅₀ of 2.83 ± 0.39 mg/kg p.o^[1].