Tesofensine

Tesofensine (NS2330) is a triple monoamine reuptake inhibitor that blocks the reuptake of norepinephrine, dopamine, and serotonin. Originally developed by NeuroSearch as a treatment for neurodegenerative diseases (Parkinson’s and Alzheimer’s), tesofensine was found during clinical trials to produce significant body weight changes as a side effect, redirecting its development toward metabolic research. The compound inhibits the dopamine transporter (DAT), norepinephrine transporter (NET), and serotonin transporter (SERT), increasing synaptic concentrations of all three monoamine neurotransmitters. This triple reuptake inhibition profile is distinct from most existing agents, which typically target one or two monoamine systems. Tesofensine has been investigated in Phase 2 and Phase 3 clinical trials for its effects on appetite, energy expenditure, and body composition. The combination of tesofensine with metoprolol (branded as Tesomet) has been investigated to mitigate cardiovascular effects of increased catecholamine signaling.

Tesofensine has been investigated for its inhibition of monoamine reuptake transporters in the central nervous system. By blocking DAT, NET, and SERT, tesofensine increases synaptic concentrations of dopamine, norepinephrine, and serotonin in brain regions controlling appetite and energy balance. Researchers observed that enhanced dopaminergic signaling in the mesolimbic reward system modulates food reward and motivation to eat, while increased noradrenergic signaling in the hypothalamus promotes sympathetic tone and energy expenditure, and serotonergic enhancement in the hypothalamic satiety circuits reduces food intake. Studies suggest that the triple monoamine mechanism engages complementary pathways not accessible to single-target agents. In Phase 2 clinical trials, researchers observed dose-dependent effects on body weight and appetite measures, with concomitant increases in heart rate attributable to peripheral noradrenergic effects. The combination with metoprolol (a beta-blocker) was designed to attenuate the heart rate increase while preserving metabolic effects.

Phase 2 Clinical Data

Astrup et al. (2008) investigated tesofensine in a Phase 2 trial in obese subjects. Researchers observed significant dose-dependent body weight reductions over 24 weeks, with the highest dose group achieving approximately double the weight loss of sibutramine [1].

Neurotransmitter Pharmacology

Lehr et al. (2008) characterized tesofensine’s triple monoamine reuptake inhibition profile, demonstrating its relative potencies at DAT, NET, and SERT and its selectivity over other receptor targets [2].

Appetite and Energy Balance

Sjödin et al. (2010) investigated tesofensine’s effects on appetite and energy expenditure in human subjects, observing reduced hunger scores and increased resting energy expenditure [3].