Selank Cycle: Schedules, and the Maths Beneath

The compound is sold in two formats, a vial of lyophilised powder and a nasal spray, and each reaches a delivered mass by a different route.

For the vial: concentration is labelled mass divided by the volume of bacteriostatic water added, and the mass drawn is concentration multiplied by the volume drawn. A U-100 syringe fills 1 mL at 100 units, so one unit is 0.01 mL.

For the spray: concentration is labelled mass divided by the fill volume, and the mass delivered is concentration multiplied by the volume the pump releases per actuation. That last figure is a property of the hardware and has to be read from its specification, not assumed.

Both routes end in the same place, a mass per event, and dividing the labelled mass by it gives the number of events in the container.

The last two rows share a bottle and differ only in the pump. Nothing on the outside of those two bottles would look different, and one delivers twice what the other does per stroke while lasting half as long.

Once a container yields a known number of events, a schedule is one more division.

The 2.5 mL vial row supplies 25 withdrawals. At one a day that container is open for 25 days. At two a day it is open for 12 or 13. The 5 mL spray at 0.1 mL per actuation supplies about 50 actuations, which is 25 days at two a day, and the arithmetic is identical in structure even though the hardware is not.

That number is more than a restocking date. It is how long the liquid sits in the container being drawn from, warmed slightly each time it is handled. A peptide in solution is a less stable arrangement than sealed lyophilised powder, and no concentration calculation tracks the decline, because the decline is not measured. The concentration you computed on day one is quoted on day 25 as though nothing had happened to the material in between.

So the fill volume is quietly also a decision about liquid shelf life. A smaller fill volume, drawn in larger fractions, empties sooner. A larger one stretches the same mass across more calendar time in solution.

Two of the numbers above are optimistic, and both losses fall on the spray.

Priming is the first. A new pump has an empty dip tube and delivers less than a full stroke until it fills, so several actuations go into charging the mechanism rather than into use. Those come off the top of the nominal count.

Residual volume is the second. The dip tube cannot reach the bottom of the bottle, so liquid remains when the pump starts pulling air. Neither loss is printed on a label, and a bottle nominally holding 50 actuations does not deliver 50 usable ones.

The vial has a smaller version of the same problem. Liquid stays in the needle hub and in the shoulder of the vial, so the final withdrawal is often short. Rounding a container down by one event is a more honest estimate than rounding it up.

Some buyers start from a powder vial and transfer the reconstituted liquid into an empty nasal bottle. That move is worth thinking through numerically, because it swaps one set of unknowns for another.

Reconstituting a 5 mg vial with 2 mL and transferring it gives 5 divided by 2, which is 2.5 mg per mL. With a pump specified at 0.1 mL, each actuation carries 2.5 times 0.1, which is 0.25 mg, or 250 mcg. That is a higher figure per stroke than any of the pre-filled rows above, purely because the same mass is sitting in less liquid.

The transfer itself loses material. Liquid stays in the vial, in the syringe used to move it and in the neck of the bottle, and none of that loss is measurable without weighing. So the concentration in the bottle is at best the calculated figure and realistically slightly under it, in an unknown direction and by an unknown amount.

What is gained is a known pump, if the empty bottle was bought with a stated actuation volume, and a known fill volume, because the preparer measured it. What is lost is precision about the total mass that arrived. Whether that trade is worth making depends on which of the two unknowns a person would rather carry, and the arithmetic makes the choice visible rather than making it for them.

Cycling as a practice came from a different pharmacology, where a break has a stated rationale: an axis that needs to recover, or a receptor population that changes under continuous exposure. Those rationales belong to the compounds they were worked out for. Carrying the vocabulary across does not carry the reasoning with it.

For this compound the honest position is that the length of a schedule is set by the container and the budget, not by a published result about duration. Cost makes that visible. On assumed figures, a 5 mg vial at 45 currency units divided across 25 withdrawals is 1.80 each. A 5 mg spray at 60 divided across 50 nominal actuations is 1.20 each, and worse once priming and residual are subtracted. Those are the numbers a schedule length actually moves.

No amount, frequency or duration for a person appears above, and none will. This is the point where a page like this one usually crosses a line, so it is worth being explicit about why it does not.

Selank is a synthetic heptapeptide derived from the endogenous peptide tuftsin, developed in Russia and studied mainly as an anxiolytic in humans within that country's clinical system. It is a registered medicine there, and that literature is real. It holds no authorisation from the FDA, the EMA or the MHRA, and there is no genuine registered Western trial, which is why no trial identifier appears anywhere on this page.

What a buyer receives from a research chemical vendor is not the registered medicine. It is material sold under the same name without an enforced manufacturing standard or a reviewed label. Arithmetic cannot bridge that gap. Division converts mass to volume and back; it has no access to clearance, safety margins or a result in people, and inventing a schedule to fill the silence would be inventing exactly the thing that is missing.