Tesofensine

1 Identity

Non-peptide small molecule of the 3-aryltropane (phenyltropane) class. Three defined stereocenters sit on the tropane bicycle at C1, C2 and C3, and the absolute configuration is part of the identity rather than a detail: an accurate mass and a single retention time do not establish it. Normally supplied and formulated as the citrate salt. There is no peptide bond, no amino acid residue, no net peptide content to determine and no counterion question in the peptide sense — but salt form and stoichiometry are still measured and declared. Two chlorines on the aryl ring give a diagnostic isotope envelope that is the cheapest identity check available on the molecule. IUPAC (1R,2R,3S)-3-(3,4-dichlorophenyl)-2-(ethoxymethyl)-8-methyl-8-azabicyclo[3.2.1]octane. Co-formulated with metoprolol as "Tesomet" in a separate development program, which is a different article and takes its own analysis. Not A peptide.

Sequence

No defined sequence, and none can be written. Tesofensine is not a peptide and contains no peptide bond. The structure is fully specified by the IUPAC name (1R,2R,3S)-3-(3,4-dichlorophenyl)-2-(ethoxymethyl)-8-methyl-8-azabicyclo[3.2.1]octane. What has to be established analytically, and what no research-chemical certificate examined has established, is the (1R,2R,3S) absolute configuration.

Molecular formula

C17H23Cl2NO (free base); C23H31Cl2NO8 for the 1:1 citrate.

Average mass

Average mass 328.277 Da (C17H23Cl2NO, free base) and 520.400 Da (C23H31Cl2NO8, the 1:1 citrate), computed from the formulas. One vendor listing publishes MW 328.28 for the free base. The free base is 63.1 percent of the citrate by mass, so 1 mg of citrate contains 0.631 mg of free base and a content claim that does not say which of the two it means is out by 58.5 percent.

Monoisotopic mass

327.11567 Da free base; [M+H]+ 328.12295. 1:1 citrate 519.14267. All three figures are computed from the formulas. The two chlorines give A diagnostic isotope envelope, M : M+2 : M+4 at approximately 100 : 64 : 10; a spectrum without that envelope is not a dichlorinated compound, and it is free evidence that takes one screenshot.

Salt / variant note

Free base C17H23Cl2NO 328.277 / 327.11567, CAS 195875-84-4. 1:1 citrate C23H31Cl2NO8 520.400 / 519.14267 — the free base is 63.1 percent of the citrate by mass. The substitution that matters is near-isobaric and invisible to the usual research-chemical certificate: RTI-111, also called dichloropane, methyl 3-(3,4-dichlorophenyl)-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylate, C16H19Cl2NO2, is 328.233 avg / 327.07928 mono. Same nominal mass, same 3,4-dichlorophenyl ring, same Cl2 isotope pattern, 0.044 Da apart on average mass. A unit-resolution instrument cannot separate them; the monoisotopic difference of 0.0364 Da is 111 ppm at m/z 327 and IS resolvable at 30,000 FWHM, but only if the certificate reports three decimal places, and most report "328". Tesofensine's own stereoisomers — the (1S,2S,3R) enantiomer and every diastereomer — are exactly isobaric at 328.277 / 327.11567 and share the isotope envelope, so mass and achiral retention time both fail and only chiral HPLC against an authentic (1R,2R,3S) standard succeeds. N-desmethyl tesofensine and the methoxymethyl homologue are both C16H21Cl2NO at 314.250 / 313.10002, 14.03 Da light and isobaric with each other. The des-chloro analogue C17H24ClNO is 293.835 / 293.15464, 34.44 Da light, and gives itself away with an M : M+2 envelope of 100 : 32 rather than 100 : 64. Cocaine C17H21NO4 at 303.358 / 303.14706 is the structural comparator that drives the analogue question and is 24.92 Da away, carrying no chlorine at all. Presentation is itself a variant class: the only retail listing found is an oral capsule.

2 Class & testing panel

Form

Single article

Testing panel

P6 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Human trial evidence exists and is unusually well developed for this catalog, and the most important item in it has never been published. Phase 2 (TIPO-1), published: Astrup et al., Lancet 2008;372:1906-1913, PMID 18950853, registered as NCT00394667 (NeuroSearch A/S, Phase 2, obesity, n=200, completed). Mechanistic human studies: Sjodin et al., Int J Obes 2010;34:1634-1643, PMID 20479765; Gilbert et al., Obesity 2012;20:553-561, PMID 21720440. Origin of the program: developed as NS2330 for Parkinson's and Alzheimer's disease, and the obesity program was built on an unplanned observation recorded in those neurology trials (Astrup et al., Obesity 2008;16:1363-1369, PMID 18356831); NCT00153010 (NS2330 in mild-to-moderate Alzheimer's dementia, Phase 2, n=430, Boehringer Ingelheim, completed). Phase 3 registration trial ("Viking") — company-reported, never published: per Saniona's release of 17 December 2018, 24-week randomized double-blind placebo-controlled, n=372 randomized 1:1:1 to 0.25 mg, 0.50 mg or placebo, primary endpoint percent change in body weight at week 24, with safety reported as "a low but statistically significant increase in heart rate and no significant effect on blood pressure". A Europe PMC search of the tesofensine corpus returns no Phase 3 obesity RCT publication. Tesomet (tesofensine plus metoprolol) program: Huynh et al., Eur J Endocrinol 2022;186:687-700, PMID 35294397; NCT02737891 (n=60, completed); NCT03149445 (n=18, completed); NCT05198362 (withdrawn, enrollment 0). Astrup et al., Lancet 2013;382:127, PMID 23849924, is a correspondence item titled "Under-reporting of adverse effects of tesofensine" whose full text could not be retrieved during compilation, so its argument is recorded as unexamined rather than summarized. Regulatory: not approved anywhere. Medix (Saniona's partner) submitted an application to COFEPRIS in Mexico; a technical committee expressed a favorable opinion in February 2023; in November 2024 Saniona publicly announced the application had not been approved; no subsequent approval announcement appears in Saniona's releases through mid-2026. A listing that describes this compound as approved in Mexico is a red flag rather than a credential. Absences: no cardiovascular outcome trial; longest controlled exposure 24 weeks (Phase 3) or 48 weeks (Tesomet extension, abstract only); no independent replication of the obesity findings outside sponsor-run programs.

4 Storage & specification

Storage

Neat crystalline solid, citrate salt as normally supplied, in a tightly closed light-resistant container with desiccant, stored at 2-8 degrees C for stock and reference material. The compound tolerates 15-25 degrees C in transit and does not require the frozen chain the peptide catalog does, which is the single operational advantage of the class and is stated so that a receiving technician does not apply a peptide SOP by reflex. Handling controls are set from the occupational-exposure assessment for a dichlorinated tropane rather than from the general chemical-store default.

Shelf life

Provisional retest interval 36 months at 2-8 degrees C in the sealed original container, provisional pending this company's own stability data. Thirty-six months rather than the catalog's default twenty-four, because a crystalline tropane salt is markedly more stable than a lyophilized peptide and the interval should reflect the chemistry rather than a house habit. The label carries a retest date, not an expiry date.