Tesofensine

What tesofensine is

Tesofensine, formerly NS2330, is a small molecule taken as a tablet. Technically, it is a triple reuptake inhibitor: it ensures that the messengers noradrenaline, dopamine and serotonin are collected again more slowly after their release and act for longer. These three messengers help control appetite, drive and reward.

Originally, the substance was meant to help against Parkinson’s and Alzheimer’s disease. In Alzheimer’s, a phase 2b trial in 430 patients over 14 weeks was unsuccessful. In the studies, however, it was noticed that participants lost a considerable amount of weight. Tesofensine was then developed further for obesity, that is, severe overweight. Its long half-life is striking: in an analysis in Alzheimer’s patients it was 234 hours.

How it is supposed to work

The main effect is on appetite. A mechanism study in 32 overweight men showed a weight loss of 1.8 kilograms compared with placebo after 2 weeks, although participants were supposed to keep their eating habits. They felt fuller and rated their hunger as lower. Energy expenditure over 24 hours did not differ significantly; at night it was 4.6 percent higher, and fat burning increased.

Because eating is also a reward for the brain, a substance that makes dopamine act for longer intervenes precisely in this system. Users do not describe this as abstaining through willpower, but as reduced craving. A marked dampening of appetite is consistently reported, often within the first few days. These are user reports, but they fit the mechanism and the study data.

Tablet instead of injection

The appeal of tesofensine lies in its form. The strong weight-loss drugs of recent years are mostly injections that have to be titrated up slowly and cause side effects mainly via the gastrointestinal tract. Tesofensine acts in the head, and its side-effect profile is correspondingly different: less stomach, more circulation and sleep. For people who do not want an injection or tolerate it poorly, an effective tablet would be a real gain in choice.

As with any weight-loss drug: if the appetite suppression stops, the hunger comes back. Anyone who loses weight loses muscle as well as fat. In the Tesomet study, fat-free mass fell along with fat mass. A protein-rich diet and strength training therefore remain the foundation.

The real value therefore lies less in the last few kilos before summer than in people with medically relevant overweight for whom other approaches have failed. One example is hypothalamic obesity, in which appetite control itself is disturbed after a tumor or surgery in the diencephalon and hardly any drug helps reliably. That the Tesomet combination lowered weight precisely there in a first randomized trial is an encouraging signal.

What the studies show

Phase 2 trial TIPO-1, Lancet 2008

Astrup and colleagues randomized 203 patients with obesity at 5 Danish centers to 3 doses of tesofensine or placebo, each with a calorie-reduced diet, over 24 weeks. 161 participants, 79 percent, completed the trial. Under diet and placebo they lost on average 2.0 percent; under the 3 doses, 4.5, 9.2 and 10.6 percent. The most common side effects were dry mouth, nausea, constipation, diarrhea and insomnia. Blood pressure did not rise significantly at the low and middle doses; heart rate rose by 7.4 beats per minute at the middle dose. The authors called for confirmation in phase 3 trials.

Tesomet in hypothalamic obesity, 2022

Huynh and colleagues randomized 21 adults with hypothalamic obesity to tesofensine plus metoprolol or placebo over 24 weeks; 18 completed the trial. The primary endpoint was safety. Compared with placebo, weight fell by an additional 6.3 percent; 8 of 13 participants versus 1 of 8 achieved at least 5 percent weight loss. Heart rate and blood pressure did not differ significantly. More frequent were sleep disturbances at 50 versus 13 percent, dry mouth at 43 versus 0 percent and headaches at 36 versus 0 percent. In one person, an existing anxiety disorder worsened.

Where the data stop

The most reliable published study dates from 2008, is a phase 2 trial with 203 participants and ran for 24 weeks. According to the manufacturer Saniona, phase 3 results exist, and the phase 3 trial is said to have confirmed the efficacy and safety from phase 2. A peer-reviewed full publication of these data could not be found. For long-term effects, weight maintenance after stopping and hard endpoints such as heart attacks, there are no data.

The comparison with the modern injections has not been tested directly either. The claim that tesofensine plays in the same league rests on comparing different studies with different participants and durations. Tesomet has been studied as a full publication in a single small study with 21 people and a rare disease. The user reports from the scene concern gray-market products whose content no one checks.

Status, approval and legal

Tesofensine is not approved as a medicine in Germany, the EU or the US, so dosage information is omitted. In Mexico, the partner Medix has filed an application for approval. The technical committee of the authority COFEPRIS gave a positive opinion in February 2023; according to the manufacturer, this was a non-binding opinion. In November 2024, Saniona announced that approval had not yet been granted; in February 2025, Medix announced a revised submission. A granted approval could not be found as of September 2026. In sport, tesofensine is explicitly listed among the stimulants on the 2026 WADA Prohibited List, prohibited in competition.

Safety

Tesofensine has an activating effect. The most important point is the cardiovascular system: in the Lancet trial, heart rate rose by 7.4 beats per minute at the middle dose, which is why the combination with a beta blocker was developed. Common are dry mouth, sleep disturbances, nausea and digestive complaints, along with effects on mood and restlessness. People with cardiovascular disease, high blood pressure, anxiety disorders or taking psychotropic drugs, especially serotonergic antidepressants, are not candidates. Gray-market products are a risk of their own: with such a low-dosed substance, even small deviations in content lead to an overdose. Because of the long half-life, the substance is broken down only slowly after stopping. Tesofensine, if at all, belongs under medical supervision.

Sources

• Astrup A et al., Lancet 2008 — phase 2 trial in 203 patients over 24 weeks
• Sjödin A et al., International Journal of Obesity 2010 — energy expenditure and appetite, 32 men
• Huynh K et al., European Journal of Endocrinology 2022 — Tesomet in hypothalamic obesity
• Lehr T et al., AAPS Journal 2010 — modeling of the negative Alzheimer’s trial in 430 patients
• Lehr T et al., British Journal of Clinical Pharmacology 2007 — pharmacokinetics in Alzheimer’s patients
• Saniona, tesofensine pipeline page — manufacturer statement on Mexico and phase 3
• Saniona announcement of November 12, 2024 — approval in Mexico not yet granted
• Saniona announcement of February 10, 2025 — revised submission to COFEPRIS
• WADA Prohibited List 2026, officially published in the Austrian Federal Law Gazette III No. 219/2025