Semax + Selank - Kalm / Cognitive

1 Identity

Fixed-ratio two-component article: two unmodified all-L heptapeptide free acids, co-lyophilized. No metal center, no acyl chain, no conjugate, no disulfide, no non-proteinogenic residue. Each component's full identity lives on its own record and is cross-referenced from here rather than restated. The title fixes neither molecule: sellers use "Semax" for the free acid, the C-terminal amide and the N-acetylated amidate, and "Selank" for the free acid and the amide, so a blend title inherits both ambiguities and this record requires the full form of each component on the label.

Sequence

Per component, cross-referenced. Semax H-Met-Glu-His-Phe-Pro-Gly-Pro-OH (MEHFPGP). Selank H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH (TKPRPGP). Both are free acids at the C-terminal proline. A C-terminal amide of either is a different article and a specified impurity, not a synonym.

Molecular formula

Per component; a mixture has no combined formula and none is written. Semax C37H51N9O10S as the free base; Selank C33H57N11O9 as the free base. The sulfur asymmetry is the most useful analytical fact about this pair — Semax carries one sulfur in the Met1 thioether and Selank carries none, so the isotope envelope assigns the two peaks. Counterion is measured per component: acetate on one against trifluoroacetate on the other passes a gross-weight check while the ratio is already out.

Average mass

Per component, on IUPAC 2021 abridged conventional atomic weights: Semax 813.928 Da; Selank 751.887 Da. AT A nominal 10 mg + 10 mg fill, 20 mg total, the 1.00 : 1.00 mass ratio is a molar ratio of 1.000 : 1.083 — 12.28610 and 13.29987 micromol. That is the closest any blend in this set comes to equimolar at equal mass, and it is still not equimolar. No single blend "molecular weight" is printed.

Monoisotopic mass

Per component. Semax 813.34796 neutral, [M+H]+ 814.35524. Selank 751.43407 neutral, [M+H]+ 752.44135 — 61.914 Da apart and trivially resolved. The separations that are not trivial are internal: acid against amide is 0.9840 Da on each component independently, and Semax methionine sulfoxide sits +15.9949 Da from parent.

Salt / variant note

(1) the semax fork, four molecules under one word: free acid 813.928; amide 812.94; N-Acetyl Semax 855.965; N-Acetyl Semax Amidate 854.981, the last two also carried under the trade name "Adamax". (2) the Selank fork: free acid 751.887 against amide 750.90, and N-Acetyl Selank Amidate 792.940. (3) ratio: 1:1 by mass is the commonest presentation observed, but no ratio is standard and 2:1 and 1:2 presentations circulate. (4) counterion: acetate against trifluoroacetate, per component and independently.

2 Class & testing panel

Form

Fixed-ratio blend

Testing panel

P1 — panel definitionfor both components, run per component and never once for the vial. No P2, P3, P4, P5 or P6 element is present in either chain, so the union adds nothing beyond P1 — which makes this the simplest analytical article in the blend set and leaves no excuse for a thin certificate. Five unique marker residues are available across the two components, and the primaries are chosen for hydrolysis robustness rather than for uniqueness alone

3 Primary sources & evidence

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

Published literature exists for each component, is graded on that component's record and is cross-referenced rather than restated; both files carry a substantial Russian-language corpus alongside Western analytical work. None of it is literature about this mixture, and no published study of this fixed two-component combination, and no consensus specification for it, was located.

4 Storage & specification

Storage

White to off-white co-lyophilized cake in Type I amber glass with a PTFE-lined closure, nitrogen headspace and in-pack desiccant — a non-sterile laboratory chemical, with no sterility claim and no injection format. Store at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light; the light and oxygen conditions are set by the Semax Met1 thioether and the label states that reason so a receiving technician cannot treat them as optional. Vials are equilibrated to ambient before opening, the Selank acetate being hygroscopic.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, desiccated and light-protected, from QA release — the shorter of the two component intervals, provisional pending this company's own data. The blend runs its own protocol and inherits neither component study. Stability-indicating attributes are per-component net content, the measured ratio, methionine sulfoxide, acid-amide interconversion, water, counterion and any new peak above 0.10 percent. Pulls at 0, 3, 6, 12, 18, 24 and 36 months, with a 6-month interim pull on each of the first three lots.