Sibutramine Hydrochloride

Sibutramine is an orally administered agent for the treatment of obesity. Sibutramine exerts its pharmacological actions predominantly via its secondary (M1) and primary (M2) amine metabolites. The parent compound, sibutramine, is a potent inhibitor of serotonin and norepinephrine reuptake in vivo, but not in vitro. However, metabolites M1 and M2 inhibit the reuptake of these neurotransmitters both in vitro and in vivo. In human brain tissue, M1 and M2 also inhibit dopamine reuptake in vitro, but with ~3-fold lower potency than for the reuptake inhibition of serotonin or norepinephrine. Sibutramine, M1 and M2 exhibit no evidence of anticholinergic or antihistaminergic actions. In addition, receptor binding profiles show that sibutramine, M1 and M2 have low affinity for serotonin (5-HT₁, 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2C), norepinephrine (b, b1, b3, a1 and a2), dopamine (D1 and D2), benzodiazepine, and glutamate (NMDA) receptors. These compounds also lack monoamine oxidase inhibitory activity in vitro and in vivo.