EC50: 3.5 nM (β-adrenoceptor, from rat colon), 499 nM (β-adrenoceptor, from rat uterus), 1.2 μM (β2-adrenoceptor, from cerebellum), 4.6 μM (β1-adrenoceptor1, from cortex)

Amibegron hydrochloride (SR 58611A) is a selective β-adrenoceptor agonist, with an EC ₅₀ of 3.5 nM for β-adrenoceptor in rat colon, and 499 nM in rat uterus. Amibegron hydrochloride (SR 58611A) shows little effect on β1- and β2-adrenoceptors, 5-HT uptake, noradrenaline (NA) uptake, and dopamine (DA) uptake from rat brain tissue, with IC ₅₀ s of 4.6 and 1.2, 0.58, 2.5 and 3.2 μM, respectively; exhibits no effect on 5-HT1A, 5-HT2, MAO-A and MAO-B (IC ₅₀ > 10 μM).

Amibegron hydrochloride (SR 58611A, 0.1 to 0.3 mg/kg, i.p.) potentiates the toxicity produced by yohimbine in mice. Amibegron hydrochloride (0.6 and 2 mg/kg, i.p.) is also active in the learned helplessness model of antidepressant-like activity in rats. However, Amibegron hydrochloride exhibits no effect on the spontaneous locomotor activity of mice at up to 10 mg/kg and of rats at up tp 30 mg/kg. Amibegron hydrochloride (3 and 10 mg/kg, p.o.) increases the synthesis of 5-HT and tryptophan (Trp) levels in several rodent brain areas such as cortex, hippocampus, hypothalamus, striatum. In addition, Amibegron hydrochloride (10 mg/kg, p.o.) promotes the release of 5-HT in rat prefrontal cortex. Systemic (3 mg/kg, i.v.) or chronic administration of SR58611A (10 mg/kg, p.o.) does not affect the activity of serotonergic neurons in the rat dorsal raphe nucleus.