Tesofensine

NS2330

Tesofensine (NS2330) is a metabolic & fat loss research compound. Triple monoamine reuptake inhibitor (noradrenaline, dopamine, serotonin) — cuts appetite centrally.

How Tesofensine works

Triple monoamine reuptake inhibitor (noradrenaline, dopamine, serotonin) — cuts appetite centrally.

Proposed benefits

Appetite suppression and fat loss via triple monoamine reuptake inhibition.

Where to get Tesofensine

The evidence for Tesofensine

Graded by what exists behind each claim.

✅ Clinically validated

• Reached phase 2 in humans with striking results — around 10% weight loss at 24 weeks, roughly double what any approved drug achieved at the time. It had originally been developed for Parkinson's and Alzheimer's, where it failed.
• Development for obesity stalled over cardiovascular signals — elevated heart rate and blood pressure at the effective doses — in a regulatory climate shaped by sibutramine's withdrawal for exactly that reason. It was later approved in Mexico as Obesidex.

📊 Correlative data

• Research-market use for fat loss. Reported experience is strong appetite suppression with the expected stimulant burden: insomnia, dry mouth, raised heart rate.
• Sibutramine is the cautionary precedent. It was approved, widely used, and withdrawn in 2010 after SCOUT showed increased cardiovascular events — a triple-reuptake mechanism producing exactly the harm this drug's phase 2 vital signs hinted at.

🧪 Theoretical / extrapolated

• A triple monoamine reuptake inhibitor — blocking reuptake of noradrenaline, dopamine and serotonin simultaneously, which increases satiety signaling and energy expenditure.
• Hitting all three is why it works and why it is risky. Noradrenaline drives the appetite suppression and the blood pressure; dopamine drives the reward-related reduction in eating and the abuse potential; serotonin adds satiety and the interaction risk with SSRIs.
• The cardiovascular effect is not incidental to the mechanism — it is the noradrenergic arm doing exactly what noradrenaline does.

How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →

What Tesofensine actually does

Tesofensine blocks three monoamine transporters at once, and the order of potency is the whole pharmacology. It inhibits the noradrenaline transporter, the dopamine transporter and the serotonin transporter — a triple reuptake inhibitor. Blocking a transporter does not add transmitter; it prevents the clearance of transmitter that has already been released, so the effect is proportional to existing firing. The drug amplifies whatever the neuron was already doing.

Where the appetite effect comes from, anatomically. Noradrenaline and dopamine signaling in the hypothalamus — particularly at the arcuate and paraventricular nuclei — is part of the circuit that terminates a meal; serotonin acting at 5-HT2C receptors on POMC neurons does the same. Blocking reuptake of all three raises tone in that circuit. This is the same target set the older withdrawn agents worked through, and it is why the cardiovascular effects below are predictable rather than surprising.

The drug was not designed for this. Tesofensine, development code NS2330, was developed for Parkinson's disease and Alzheimer's disease on the strength of its dopaminergic action. It failed those indications. Weight loss was observed in those trials as an unwanted effect, and the obesity program was built on that observation Abdi Beshir 2023. Knowing the history matters: the dosing, the tolerability profile and the trial designs were all inherited from a neurology program.

And the pharmacokinetic fact that dominates everything: the half-life is about 8 days. That is exceptionally long for a small molecule. Three consequences follow directly, and they are arithmetic rather than opinion. Steady state takes roughly five half-lives, so about five weeks — the effect at week two is not the effect the dose will settle at. A dose increase takes another five weeks to express itself. And when an adverse effect appears, stopping does not resolve it quickly: the concentration falls by half a week later and takes over a month to clear. Every mistake with this compound is a slow mistake.

Cell, rodent, human — and where it stops

Step one, the phase 2 trial, which is the reason anyone knows this compound. Astrup 2008 randomized 203 obese patients with BMI 30–40 to placebo or tesofensine at 0.25 mg (n=52), 0.5 mg (n=50) or 1.0 mg (n=49) daily for 24 weeks, all with a diet program. Weight loss was 2.0% on diet plus placebo, 4.5% at 0.25 mg, 9.2% at 0.5 mg and 10.6% at 1.0 mg. A clean, dose-ordered result over six months.

The same trial reports the reason the program did not continue. Heart rate rose by 7.4 beats per minute at the 0.5 mg dose, and the adverse events were dry mouth, nausea, constipation, diarrhea and insomnia Astrup 2008. The paper's own conclusion is carefully hedged — that 0.5 mg might have the potential to produce twice the weight loss of the drugs then approved. A sustained rise in heart rate and blood pressure is the exact signal that ended sibutramine, and regulators had that history in front of them.

Step two, and this is the most informative development in the compound's history. The molecule was reformulated as Tesomet — tesofensine combined with the beta-blocker metoprolol in the same product. Huynh 2022 randomized 21 adults with hypothalamic obesity to Tesomet (0.5 mg tesofensine plus 50 mg metoprolol) or placebo for 24 weeks: 6.3% additional weight loss versus placebo, P=0.017, with 8 of 13 reaching at least 5% weight loss. Adverse events were sleep disturbance in 50%, dry mouth in 43%, headache in 36%, and exacerbation of anxiety.

Read that combination product properly, because it is the compound's own developers telling you what the problem is. Adding a beta-blocker to the pill is an admission that the cardiovascular effect is not incidental. It is a designed countermeasure, in a fixed dose, given to everyone. Anyone taking tesofensine alone is taking the half of that product that needed the other half.

The obstacles, named one at a time. (1) The largest trial is 203 people over 24 weeks Astrup 2008; obesity drugs are now judged on cardiovascular outcome trials with thousands of patients over years. (2) The 21-patient Tesomet trial is in hypothalamic obesity Huynh 2022, a rare condition following hypothalamic damage, which is a specific population and not the general one. (3) The compound is not approved anywhere for obesity, so there is no post-marketing safety database at all. (4) The comparator landscape has changed completely: Abdi Beshir 2023 reviews the approved and emerging agents, and 10.6% at 24 weeks was impressive in 2008 and is no longer the benchmark.

What would have to be true, and how you would know it was not

This is an unapproved investigational drug, and this page is education about its pharmacology rather than guidance on using it. Three predictions, and the first two are the ones the trials themselves point at.

1. Heart rate and blood pressure are the primary measurements, and they are not blood tests. The phase 2 trial measured a 7.4 bpm rise at 0.5 mg Astrup 2008 and the successor product added a beta-blocker to manage it Huynh 2022. Resting heart rate and blood pressure, measured at the same time of day, seated, over a two-week baseline and then weekly, are the instrument that matters. Because the half-life is about 8 days, a reading at week two understates where the drug will settle — which is precisely the trap.

2. The falsification test for the metabolic story is whether the metabolic markers follow the weight. Weight loss from any cause normally improves HbA1c, fasting insulin and the lipid panel. Draw all three at baseline and at 24 weeks. The prediction that cuts against the product is this: a monoamine-driven reduction in intake produces loss of lean mass alongside fat unless training and protein are held deliberately high, and lean mass loss will not show on a scale. Body composition, not weight, is the honest endpoint.

3. TSH and a CMP separate the drug from everything else that changes weight. Thyroid dysfunction is the most common medical confounder of a weight trajectory in either direction, and TSH costs almost nothing. A CMP covers electrolytes and renal and hepatic function, which matter for any sympathomimetic taken for months.

What nobody has tested yet

Four things nobody has established about this compound.

Nobody has run a cardiovascular outcome trial. The signal that stopped the program was a surrogate — heart rate and blood pressure Astrup 2008. Whether that translates into events has never been tested, and it is the question that determines whether the drug is dangerous or merely suspicious. Given the size of trial required, it will probably never be answered.

Nobody has published body composition properly. The phase 2 trial reported body composition as an endpoint alongside weight Astrup 2008; the fat-versus-lean split at each dose over 24 weeks is the number that would tell a person what they are actually losing, and it is not what gets quoted.

Nobody has tested tesofensine against a modern incretin. The comparator in 2008 was orlistat-era pharmacology Abdi Beshir 2023. A head-to-head against a current agent, with cardiovascular monitoring, would establish whether a triple monoamine reuptake inhibitor has any remaining place, and nobody has commercial reason to run it.

Nobody has characterized what happens on stopping. With an 8-day half-life the washout is slow, and whether appetite and weight rebound gradually with the concentration or abruptly at some threshold has never been described. That is a straightforward observational follow-up of an existing trial cohort and it does not exist.

Tesofensine — its own safety story, not its class's

The class block above is generic. Four things belong to this compound specifically.

The cardiovascular effect is the defining risk and it is documented, not theoretical. A 7.4 bpm rise at the middle dose in a randomized trial Astrup 2008, and a successor product that packages a beta-blocker with the drug Huynh 2022. Sibutramine — a dual noradrenaline and serotonin reuptake inhibitor — was withdrawn worldwide after a cardiovascular outcome trial showed increased events. Tesofensine hits the same transporters plus dopamine, and no equivalent outcome trial has ever been run. That is the correct frame: not a proven harm, an unexamined one with a bad precedent.

The dopaminergic arm carries a psychiatric risk the noradrenergic drugs did not. The Tesomet trial reported sleep disturbance in 50% and exacerbation of anxiety Huynh 2022. Dopamine transporter blockade is the mechanism shared with stimulants, and it brings the potential for mood disturbance and for reinforcing effects. This is a reason the drug belongs in supervised settings and a reason the anxiety history of the person taking it is not a detail.

The serotonergic interaction is the one that could be dangerous fast. Combining a serotonin reuptake inhibitor with another serotonergic agent — an SSRI, an SNRI, tramadol, an MAOI, high-dose 5-HTP — risks serotonin syndrome. With an 8-day half-life, stopping tesofensine does not create a safe window for weeks, which is the specific detail that makes this more hazardous than the same interaction with a short-acting drug.

The long half-life turns every error into a slow one. Five weeks to steady state, over a month to clear. A person who feels fine at week two and escalates is committing to an exposure they will not see for another month, and a person who develops a problem cannot undo it quickly. That single pharmacokinetic fact deserves more weight than any individual adverse event on the list.

Sources read for this page

• Astrup A, et al. Effect of tesofensine on bodyweight loss, body composition, and quality of life in obese patients: a randomised, double-blind, placebo-controlled trial. The Lancet 2008 · PMID 18950853
• Huynh K, et al. Randomized controlled trial of Tesomet for weight loss in hypothalamic obesity. European Journal of Endocrinology 2022 · PMID 35294397
• Abdi Beshir S, et al. A narrative review of approved and emerging anti-obesity medications. Saudi Pharmaceutical Journal 2023 · PMID 37712012

Tesofensine — safety, predicted from mechanism

Tesofensine — interference & stacking

Bloodwork to run alongside Tesofensine

Baseline first, then again at 8–12 weeks.

The Metabolic Health & Prediabetes panel covers these in one order — 8 markers, $81.45 with the discount applied.

Check results you already have → · All 103 markers A–Z

Tesofensine — frequently asked questions

What Tesofensine is used for

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