Semax Price: $3.00/mg Against Selank at $2.38/mg

There is one listing, so every row below buys the same material under different terms. The last column is the only one that survives a comparison against another storefront, because vial prices are not comparable unless the vials are the same size.

A 10 mg vial holds ten milligrams, so the division is a decimal point: $59.99 becomes $5.999 and rounds to $6.00, $30.00 becomes $3.00 exactly. Two roundings are worth naming, because a careful reader spots them and then distrusts the page. Half of $59.99 is $29.995, which the storefront shows as $30.00, and that half cent carries through to a per milligram rate of $2.9995 quoted here as $3.00. Both round up, both by half a cent, and neither changes anything.

Inverted, a dollar buys 167 mcg at list and 333 mcg with the code. That is the check to run on any listing quoting a bottle price without a mass: if you cannot say how many micrograms a dollar buys, it is not a price yet.

The tier column is included because it is the honest comparison, not because it wins. Ten vials at the 10% tier is $5.40 a milligram, still 80 percent above the single vial code rate.

Semax and Selank are the two Russian nootropic heptapeptides, they sell from the same catalogue in the same 10 mg lyophilised format, and the price gap between them is the most useful number on this page.

Sixty two cents a milligram on the label, 26 percent, and the gap widens rather than closes when both are divided by their weighed contents, because the Selank batch is the more generously overfilled of the two. Anyone choosing between them purely on price is choosing Selank, and the arithmetic says so plainly.

The obvious explanation for the premium is documentation, and it does not survive checking, which is worth saying plainly on a page that exists to check things. Ascension publishes two certificates for each of the two compounds, and they match each other almost line for line. February, both from MZ Biolabs: purity, quantity and identity, with no endotoxin test and no sterility screen in either. June, both from Kovera two weeks apart: purity, net content, identity by LC-MS, endotoxin, a rapid sterility screen and heavy metals, on both. The testing scope on this catalogue moved in June across the line rather than for one product, so the 62 cents does not buy a test the cheaper vial lacks. It buys a different molecule at a different price, and whatever else it buys is not visible on the paperwork. Our Selank price breakdown runs the same division from the other side.

The rate to carry is $3.00 per milligram on the label. The footnote is $2.67 on batch 30-05260628. Quote the first at anyone; treat the second as belonging to one batch number.

Every figure so far counts ten milligrams because ten is the number printed on the vial. The certificate counts 11.23.

Two published lots, two different answers, and the 29 cent spread between them is the size of the manufacturing tolerance in practice. MZ Biolabs measured lot 30-01260229 at 10.12 mg on 9 February 2026, barely over the label. Kovera weighed batch 30-05260628 at 11.23 mg, which is 12.3 percent over, against a specification written as approximately 10 mg rather than exactly 10 mg. Overfill is a tolerance and not a commitment any listing makes, so quoting $2.67 as the Semax price is quoting the more generous of two real lots.

The purity row is there to show how little it moves. Purity and quantity answer different questions: 99.886% of 11.23 mg is 11.22 mg of Semax and roughly 0.013 mg of everything else, which at two decimal places does not change the rate at all. That is unusual and worth noticing. On a vial certified at 98 percent the same adjustment would cost you a couple of cents a milligram; here the purity figure is high enough that the mass and the pure mass are the same number.

What the certificate reports, in full, so the numbers above can be checked: purity 99.886% against a specification of greater than 98%, net content 11.23 mg against approximately 10 mg, identity confirmed by LC-MS, an endotoxin screen against a 0.5 EU/mL limit, a microbial sterility screen returning no growth, and arsenic, cadmium, lead and mercury all below their ICP-MS acceptance limits.

The vial arrives dry and has no concentration until a volume is chosen for it. That choice sets the mg/mL and the smallest quantity a barrel can resolve, and it does not move the price by a cent.

At 2 mL the arithmetic is as clean as this compound gets. One unit on a U-100 barrel is 0.01 mL, which at 5 mg/mL holds 50 mcg, so 10 units draws 500 mcg and the whole vial is 200 units of volume. Half a milligram therefore costs $1.50 with the code in every row of that table, because half a milligram is half a milligram whatever it is dissolved in.

The cost per unit column is the opposite, and it is the trap. It reads $0.30 at 1 mL and $0.06 at 5 mL for exactly the same purchase, because a unit is a volume and not a mass. Cost per unit only compares across two vials when the concentrations match, which is why every headline figure on this site is per milligram. Our syringe measurement guide covers reading a U-100 barrel, and the reconstitution guide covers the handling side.

The overfill changes this table too, and almost nobody runs the second calculation. Put 2 mL into a vial you believe holds 10 mg and you write 5 mg/mL on the cap. If the vial actually holds 11.23 mg, the solution is 5.615 mg/mL, each unit carries 56.15 mcg rather than 50, and 10 units draws 562 mcg rather than 500. The correction is arithmetic, not chemistry: divide the net content on your own batch certificate by your diluent volume instead of dividing the label figure. If no net content is published for the batch you were sent, the label figure is what you have. The Semax reconstitution calculator will run any volume you enter. These are laboratory handling figures for research material and nothing else.

Cost per milligram compares mass. It does not compare molecules, and on two peptides of different weight those are different rankings.

Semax is a heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro, the ACTH(4-7) fragment with a Pro-Gly-Pro tail added to slow enzymatic breakdown. PubChem registers it as CID 9811102 with the formula C37H51N9O10S and a molecular weight of 813.9. Selank is also a heptapeptide but a different molecule with a different sequence, at 751.9. A Semax molecule is about 8 percent heavier, so a milligram of it contains about 8 percent fewer molecules.

Priced per milligram the gap is 26 percent. Priced per micromole it is 37 percent, because the heavier molecule loses twice: once on the sticker and again on the count.

None of this makes one compound better value, because molarity is not potency either. Two peptides with different targets are not interchangeable at any exchange rate. The point applies to every per milligram figure here: mass pricing is fair between two batches of one compound and rough between two molecules. Our reference page on dosing sources covers what the literature does and does not establish.

A rate per milligram measures one thing. Four it does not measure move the real cost further than any discount here.

• Regulatory standing. Semax appears on FDA's list of bulk drug substances nominated but withdrawn: nominated, placed in category 2 under the interim policies, then withdrawn by the nominator. It is in none of the three current 503A categories and is not FDA approved for any indication. Reading that it is category 2 today is reading a stale fact.
• The immunogenicity question. FDA writes that compounded drugs containing semax (heptapeptide) may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation and peptide-related impurities, and that the agency lacks sufficient information to know whether the drug would cause harm if administered to humans. Aggregation and impurities are measurable, which is exactly why the endotoxin and sterility lines on this certificate are worth more than the purity line most listings lead with.
• What the sterility line is. The report describes a rapid sterility screen, two days of incubation at 30 to 35 degrees, bacteria and fungi both returning no growth, and it says on its own face that full USP Chapter 71 sterility testing may be required for regulatory compliance. That is a real result and a limited one, and reading it as a sterility guarantee is the mistake this page exists to prevent.
• Landed cost. Freight divides by ten milligrams rather than scaling with them, so it lands hard on one vial and softly on ten. Free carriage starts at $250, and the code pushes that line further away because it halves the number the threshold measures.

One smaller effect is large on a vial this size. Solution left in the vial shoulder and the needle hub cannot be recovered: 0.05 mL out of a 2 mL preparation is 2.5 percent, moving the effective rate from $3.00 to $3.08 per milligram. No coupon touches it.

On the same storefront, Semax at $3.00 sits between BPC-157 at $2.45 and MOTS-c at $3.75, with retatrutide at $4.95 above all three. Our BPC-157 price page and MOTS-c price page run the same division on those vials.