What is Selank Nasal Spray?
Selank is H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH, CAS 129954-34-3, formula C33H57N11O9, molecular weight 751.88, seven residues. It is built from the tuftsin sequence Thr-Lys-Pro-Arg, a fragment of the immunoglobulin G heavy chain, with a Pro-Gly-Pro extension added at the C-terminus. The three prolines give the backbone a rigid, kinked conformation, and the lysine and arginine side chains make the molecule strongly basic and very water soluble.
The spray is a delivery format, not a different compound. Mucosal delivery has a substantial formulation literature, since the nasal epithelium is thin, richly vascularized and bypasses first-pass hepatic metabolism in absorption studies. Selank was developed in Russia as an intranasal preparation, and much of the rodent behavioural and neurochemical work on it, including studies of GABAergic signaling and monoamine turnover, used solutions of this general type.
What is not settled is the quantitative side. Published transmucosal absorption fractions for peptides of this size span a wide range and depend on pH, tonicity, viscosity and mucociliary clearance, none of which transfer cleanly between species. How much intact peptide rather than fragment crosses the epithelium also remains debated.
Reconstitution & handling
No reconstitution applies, because the peptide arrives already dissolved in a buffered isotonic vehicle. The arithmetic starts from the label. The 10 mg total content divided by fill volume gives nominal concentration, and dividing that by the metered volume per actuation gives mass per actuation. The bottle should not be diluted, since buffer and tonicity affect stability.
Storage & stability
Sealed bottles are held refrigerated at 2 to 8 degrees Celsius and protected from light, since a peptide in solution is less stable than the same molecule lyophilized at -20 degrees Celsius. Freezing is avoided because ice formation concentrates solutes. Selank contains no cysteine or methionine, so it is comparatively free of oxidative liabilities, and the shelf-life limit is slow backbone hydrolysis.
How it's tested
Solution lots are assayed by reverse-phase HPLC at 214 and 220 nanometres, quantified against a reference standard to confirm the declared 10 mg content rather than reported only as area percentage. Mass spectrometry confirms identity against the theoretical average mass of 751.88. Fill volume, pH, appearance and sterility are recorded, and a lot-matched certificate of analysis is available.