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Selank 5 mg Vial: Reconstitution and Dosing Chart

How much bacteriostatic water to add to a 5 mg vial of Selank, the concentration you get, and a full dose-to-units chart.

Medical review pendingTuftsin analogUpdated
Vial size
5 mg
With 2 mL water
2.5 mg/mL
common choice
10 units contain
250 mcg
at 2 mL, U-100
Whole vial
200 units
2 mL on a U-100 scale

How much water to add

Bacteriostatic water only changes the concentration, not the amount of Selank in the vial. More water means more units per dose (easier to read), less water means fewer.

Selank 5 mg vial: concentration by water added
Water addedConcentration10 units contain100 mcg isWhole vial
1 mL5 mg/mL500 mcg2 u100 u
2 mL2.5 mg/mL250 mcg4 u200 u
2.5 mL2 mg/mL200 mcg5 u250 u
3 mL1.667 mg/mL166.7 mcg6 u300 u

Calculator and full dosing table

Preset to the 5 mg vial. Change any value; the table below the result updates with it.

1Vial size
2Bacteriostatic water added
3Dose per injection
4Syringe (U-100)
Draw to
20units
= 0.2 mL on a 1 mL U-100 insulin syringe
5 mg vial2 mL water500 mcg dose
Concentration
2.5 mg/mL
Doses per vial
10
Weeks (1 dose/wk)
10
Math only. It does not recommend a dose.

20 units (0.2 mL) on a 1 mL U-100 syringe: 500 mcg from a 5 mg vial + 2 mL water (Selank).

Dosing table for a 5 mg vial

Syringe units (U-100) for each dose, by how much bacteriostatic water you add.

Selank: U-100 syringe units per dose for a 5 mg vial
Dose1 mL water2 mL water2.5 mL water3 mL water
100 mcg2456
250 mcg51012.515
300 mcg6121518
500 mcg10202530
750 mcg153037.545
1000 mcg20405060

How the math works

Concentration is the vial's milligrams divided by the water you add. Volume to draw is your dose divided by that concentration. On a U-100 syringe, 1 mL is 100 units, so units = mL × 100.

5 mg ÷ 2 mL = 2.5 mg/mL
500 mcg = 0.5 mg; 0.5 mg ÷ 2.5 mg/mL = 0.2 mL
0.2 mL × 100 = 20 units
20 units · 0.2 mL · 500 mcg from 5 mg + 2 mL
Math only. The amounts in these tables are reference values for the arithmetic, not dose recommendations.

What the quoted selank amounts are, for a 5 mg vial

Rats in a learning study received selank at 300 microg/kg, a per-kg animal dose that is not converted to a human amount.[3]

Mice received selank at 100 micrograms/kg, again a per-kg animal dose that is not converted.[4]

The 4 cached human selank abstracts give no mg or mcg dose, so there is no sourced human amount to divide a 5 mg vial into; 0 of 4 state one.

Calculated from vial mg 5; abstracts checked 18454096, 26356395, 25176261, 18577961; abstracts stating adose 0. Formula: count of abstracts stating a dose = 0

What a 5 mg selank vial gives

Mixed with 1, 2 or 3 mL of water, a 5 mg selank vial is 5, 2.5 or 1.667 mg/mL, so one U-100 unit holds 50, 25 or 16.667 mcg.

Calculated from vial mg 5; water mL 1, 2, 3; u100 units per mL 100. Formula: mg/mL = vialMg / waterMl; mcg per unit = mg/mL x 10

A 5 mg selank vial holds 5000 mcg in total, which is 50 mcg per unit if mixed to 1 mL and 16.667 mcg per unit if mixed to 3 mL.

Calculated from vial mg 5. Formula: mcg = vialMg x 1000; per unit = mcg / (100 x mL)

Is 5 mg a labelled selank strength?

Drugs@FDA returns the message "No matches found!" for selank, so there is no FDA-labelled selank strength.[5]

With 0 matching applications in Drugs@FDA there is no labelled strength to compare a 5 mg selank vial with.

Calculated from vial mg 5; drugs fda matches 0; source s2-legal/api.fda.gov/drugsfda-selank.txt. Formula: labelled strengths available = 0

Common questions

How much water goes in a 5 mg vial of Selank?

That choice only changes the concentration. With 2 mL, a 5 mg vial is 2.5 mg/mL; with 1 mL it is 5 mg/mL. Less water means fewer units per dose and harder-to-read marks for small doses.

How many units is 100 mcg from a 5 mg vial?

With 2 mL of water, 100 mcg is 4 units on a U-100 syringe. With other water amounts, see the table.

How many doses are in a 5 mg vial?

Divide the vial size by the dose (in the same unit). The calculator on this page shows the number of whole doses for any dose you pick.

How much bacteriostatic water for a 5mg selank vial?

The water volume only sets the strength: 5 mg of selank in 1, 2 or 3 mL is 5, 2.5 or 1.667 mg/mL, which is 50, 25 or 16.667 mcg per syringe unit.

Calculated from vial mg 5; water mL 1, 2, 3. Formula: mg/mL = vialMg / waterMl; mcg per unit = mg/mL x 10

More on Selank

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.BenefitsClaimed benefits next to what published studies measured.How it worksTarget, mechanism and how long it acts, from the label or studies.Nasal sprayStudies that gave Selank as nasal spray, and what is approved.

Sources

  1. 1Metric (SI) Prefixes (NIST Reference on Constants, Units, and Uncertainty)National Institute of Standards and Technology (NIST) · 2025physics.nist.govAccessed 2 Oct 2026
  2. 2BASAGLAR (insulin glargine) injection, prescribing information (DailyMed)U.S. Food and Drug Administration / DailyMed (Eli Lilly and Company label) · 2026dailymed.nlm.nih.govAccessed 2 Oct 2026
  3. 3The optimizing action of the synthetic peptide Selank on a conditioned active avoidance reflex in rats.Neuroscience and behavioral physiology · 2003PMID 14552529Accessed 2 Oct 2026
  4. 4Effects of Selank on behavioral reactions and activities of plasma enkephalin-degrading enzymes in mice with different phenotypes of emotional and stress reactions.Bulletin of experimental biology and medicine · 2002PMID 12432865Accessed 2 Oct 2026
  5. 5Drugs@FDA (openFDA) search: active ingredient "selank"U.S. Food and Drug Administration · 2026api.fda.govAccessed 2 Oct 2026

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