Short answer: With 2 mL of bacteriostatic water in a Selank + Semax, 5 mg + 5 mg vial (5 mg Selank + 5 mg Semax), every 10 units on a U-100 insulin syringe holds 250 mcg Selank and 250 mcg Semax. The ratio is fixed, so you cannot change one peptide without changing the others. Amounts are arithmetic on the label, not dose advice.
This blend puts selank and semax, two short synthetic peptides whose human research is mostly published in Russian, in one vial. Both are on FDA's list of compounding substances that were nominated and then withdrawn.
The vial most listings show is 5 mg + 5 mg (10 mg total), which is 1:1. A larger vial with more selank than semax also appears; if yours is not 1:1, use the blend calculator with your label's amounts.
| Peptide | Commonly labeled | Share of vial | Guide |
|---|---|---|---|
| Selank | 5 mg | 50% | Selank guide |
| Semax | 5 mg | 50% | Semax guide |
The water volume changes how big each draw is, not what is in the vial. The highlighted row is 2 mL.
| Water added | Units in vial | Selank / 10 units | Semax / 10 units |
|---|---|---|---|
| 2 mL | 200 | 250 mcg | 250 mcg |
| 3 mL | 300 | 166.7 mcg | 166.7 mcg |
| 5 mL | 500 | 100 mcg | 100 mcg |
| Units drawn | Volume | Selank | Semax |
|---|---|---|---|
| 5 units | 0.05 mL | 125 mcg | 125 mcg |
| 10 units | 0.1 mL | 250 mcg | 250 mcg |
| 20 units | 0.2 mL | 500 mcg | 500 mcg |
| 30 units | 0.3 mL | 750 mcg | 750 mcg |
For any other vial, water volume or draw, the free peptide blend calculator does the same math for 2 to 5 peptides.
mg of that peptide ÷ mL of water. For Selank + Semax, 5 mg + 5 mg with 2 mL: Selank 5 ÷ 2 = 2.5 mg/mL, Semax 5 ÷ 2 = 2.5 mg/mL.amount ÷ its concentration = mL. Example: 250 mcg of Semax is 0.25 ÷ 2.5 = 0.1 mL.mL × 100 on a U-100 syringe: 0.1 × 100 = 10 units.mL × concentration for each other peptide: 250 mcg Selank.A blend is one solution, so every draw takes the same share of each peptide. In the example above, drawing 10 units for 250 mcg of Semax also gives 250 mcg Selank. Doubling the draw to 20 units doubles all of them, to 500 mcg Selank. There is no draw that changes one peptide and leaves the others where they are.
More or less water does not help either: it changes how many units each draw is, not the ratio between the peptides. If you need to set the amount of each peptide on its own, they have to be in separate vials (a stack), each with its own single-peptide calculation.
We found no published human study of Selank + Semax blend as a blend. Below is what is published for each peptide on its own. "Amounts studied" are what a study gave or reported, often by a different route; they are not personalized advice. Confirm anything about your own use with your prescriber.
Not FDA approved. Human research is small and mostly published in Russian: one study of 62 patients with generalized anxiety disorder or neurasthenia compared selank (30 patients) with medazepam (32 patients) and reported similar anti-anxiety effects, and another compared selank with phenazepam in 60 patients with phobic-anxiety and somatoform disorders. [1][2][3]
Amounts studied: The PubMed abstracts of those two studies do not state the amount or route given. A 2020 brain-imaging study in 52 healthy people gave selank, semax or placebo, each on its own, by injection.
FDA compounding list: On FDA's page of bulk drug substances that may present significant safety risks in compounding, selank acetate (TP-7) is in the "nominated but withdrawn" list. FDA says it "lacks important information regarding any safety issues raised by selank acetate administered to humans." [4]
Not FDA approved. A heptapeptide; human research is mostly published in Russian. One study followed 110 patients after ischemic stroke and compared those who did and did not receive semax; it reported higher blood BDNF levels and better recovery scores (Barthel index) with semax. [5][3]
Amounts studied: In that stroke study: 6000 mcg a day in two 10-day courses, 20 days apart (the abstract does not state the route). A 2020 brain-imaging study in 52 healthy people gave semax, selank or placebo, each on its own, by injection.
FDA compounding list: On FDA's page of bulk drug substances that may present significant safety risks in compounding, semax (heptapeptide) is in the "nominated but withdrawn" list. FDA says it has "no, or limited, safety-related information for proposed routes of administration." [4]
Regulatory status. Neither selank nor semax is FDA approved. Both are in the "nominated but withdrawn" list on FDA's page of bulk drug substances that may present significant safety risks in compounding. FDA describes that list as substances "previously in category 2" that "were withdrawn by the nominators." [4]
Blend compositions were checked against several retail product listings in October 2026. We do not name or link sellers.