How Much Bacteriostatic Water for a Dihexa 10 mg Vial

A 10 mg vial of Dihexa reconstituted with 2 mL of bacteriostatic water gives a concentration of 5 mg/mL (5,000 mcg/mL); with 1 mL it gives 10 mg/mL. The calculation depends only on the quantity in the vial and the volume added, so the figures below apply to any 10 mg vial.

Dihexa reconstitution calculator

Set to this vial below. Change the vial size, water volume, amount or syringe and it recalculates the concentration and the syringe units. For laboratory research use only.

Desired dose

0.5 mg 1 mg 1.5 mg 2 mg 2.5 mg 3 mg 3.5 mg 4 mg 4.5 mg 5 mg Custom… Milligrams (mg) Micrograms (mcg)

1 mg = 1000 mcg

Research peptide in vial (mg) 5 mg 10 mg 20 mg 30 mg Custom… As printed on the vial

Bacteriostatic water added (ml) 1 mL 2 mL 3 mL Custom… Total volume you put in the vial

Syringe size 0.3 ml — 30 units 0.5 ml — 50 units 1.0 ml — 100 units Custom…

Draw to 5.0units

Concentration—

Volume per dose—

Doses per vial—

All products are sold strictly for laboratory research use only and are not for human or veterinary consumption. This calculator is provided as a general reference tool.

How much bacteriostatic water for 10 mg Dihexa?

Add 2 mL of bacteriostatic water to a 10 mg Dihexa vial for 5 mg/mL, so 0.1 mL (10 units) holds 0.5 mg (500 mcg); 1 mL gives 10 mg/mL, 3 mL gives 3.33 mg/mL and 5 mL gives 2 mg/mL. The vial holds 10 mg whichever volume you choose, and only the concentration moves.

Water added	Concentration	Amount in 0.1 mL (10 units on a U-100 syringe)
1 mL	10 mg/mL	1 mg (1,000 mcg)
2 mL	5 mg/mL	0.5 mg (500 mcg)
3 mL	3.33 mg/mL	0.33 mg (333 mcg)
5 mL	2 mg/mL	0.2 mg (200 mcg)

Concentration by water volume

Concentration is the quantity in the vial divided by the volume. A 10 mg vial holds 10 mg whether it receives 1 mL or 5 mL; only the mg/mL figure moves. The right-hand column converts each concentration into the number of U-100 units that contain 1 mg.

Water added to 10 mg	Concentration	Units containing 1 mg
1 mL	10 mg/mL	10 units
2 mL	5 mg/mL	20 units
3 mL	3.33 mg/mL	30 units
5 mL	2 mg/mL	50 units

Before choosing a larger volume, check that the vial has headspace for it. One multi-dose vial of bacteriostatic water covers several research vials.

Reading the concentration on a U-100 syringe

A U-100 insulin syringe is graduated in units, and 100 units equal 1 mL. Units are therefore millilitres multiplied by 100: 0.1 mL is 10 units and 0.25 mL is 25 units. A 0.5 mL syringe carries 50 units and a 0.3 mL syringe carries 30 units on the same scale, with finer markings that make small volumes easier to read.

To find the volume that contains a given amount, divide the amount by the concentration. At 5 mg/mL (a 10 mg vial with 2 mL of water), the volume that contains 1 mg is 1 divided by 5, which is 0.2 mL, or 20 units. The table below runs the same calculation for four arbitrary amounts. They illustrate the arithmetic and nothing else.

Amount (illustrative)	Volume at 5 mg/mL	U-100 units
0.25 mg (250 mcg)	0.05 mL	5 units
0.5 mg (500 mcg)	0.1 mL	10 units
1 mg	0.2 mL	20 units
2 mg	0.4 mL	40 units

At 2 mg/mL, which the same vial gives with 5 mL of water, every volume in the table is 2.5 times larger: a 1 mg draw measures 50 units instead of 20. Volumes below about 0.1 mL are hard to read accurately on a 1 mL syringe. Either move to a 0.3 mL or 0.5 mL syringe, or reconstitute with more water so that the same mass occupies a larger, more legible volume.

Dihexa and water solubility

Dihexa was designed to be hydrophobic so that it could cross biological barriers, and its developers describe it as very hydrophobic (McCoy et al., J Pharmacol Exp Ther, 2013). Chemical suppliers’ data sheets list it as insoluble in water and soluble in DMSO. In the published laboratory work, Dihexa was dissolved in a small amount of DMSO before dilution: for example, 2.5% DMSO in phosphate-buffered saline (Martino et al., Neurotrauma Rep, 2025), or a DMSO, PEG300, Tween-80 and saline mix (Sun et al., Brain Sci, 2021). For oral work in the 2013 study it was given as a suspension in saline.

The concentration figures on this page describe the quantity per millilitre of the final volume. They hold whether that volume is bacteriostatic water alone or a small amount of co-solvent brought up to the same final volume.

The Dihexa vial

Dihexa is N-hexanoic-Tyr-Ile-(6) aminohexanoic amide, a small, metabolically stabilised analogue of angiotensin IV developed at Washington State University, with a molecular weight of about 504.7. In serum it lasted about 335 minutes, against under 2 minutes for its parent compound (McCoy et al., 2013). This page covers the 10 mg lyophilised vial. Certificates of analysis are on the Lab Reports page. What the research showed is in What Is Dihexa?

Reconstitution technique

Let the vial reach room temperature, swab both stoppers, and run the measured water slowly down the inside wall of the vial rather than onto the powder. Swirl or tilt gently until the cake dissolves, never shake, and give any remaining powder a few minutes to settle into solution. Label the vial with the date and the concentration, then keep it refrigerated at 2 to 8 °C and protected from light. The full method, with the reason behind each step, is in how to reconstitute peptides with bacteriostatic water.

What the solution should look like

A fully dissolved solution is clear and colourless. Haze, strands or powder that will not disperse can mean the water went in too fast or the vial was shaken, or, for a compound with limited water solubility such as Dihexa, that the concentration is high for the volume; a larger volume lowers it. Haze that appears later points to warm or bright storage. The causes are covered in why peptides gel or go cloudy.

Bacteriostatic water, not sterile water

Bacteriostatic water is sterile water with 0.9% benzyl alcohol, a preservative that allows a refrigerated vial to be accessed more than once; plain sterile water is intended for single access. The difference is explained in bacteriostatic water explained.

Frequently asked questions

How much bacteriostatic water do I add to a 10 mg vial of Dihexa?

There is no single correct volume. With 2 mL of bacteriostatic water a 10 mg vial of Dihexa gives 5 mg/mL, so 0.1 mL (10 units) holds 0.5 mg (500 mcg); with 1 mL it gives 10 mg/mL. Adding more water does not change the quantity in the vial, so write the concentration you chose on the vial.

How many units on a U-100 syringe contain 1 mg at 5 mg/mL?

At 5 mg/mL (a 10 mg vial with 2 mL of water), the volume that contains 1 mg is 1 divided by 5, which is 0.2 mL, or 20 units. Units are millilitres multiplied by 100, so 0.1 mL is 10 units. The amounts on this page illustrate the arithmetic only.

What did published research use to dissolve Dihexa?

Dihexa is hydrophobic and has limited solubility in plain water. Published laboratory studies dissolved it in a small amount of DMSO before dilution, for example 2.5% DMSO in phosphate-buffered saline (2025), and gave it as a suspension in saline for oral work (2013).

Can I use sterile water instead of bacteriostatic water?

Only for a vial that will be accessed once. Bacteriostatic water is sterile water with 0.9% benzyl alcohol, a preservative that allows a refrigerated vial to be accessed more than once; plain sterile water is intended for single access.

How should a reconstituted Dihexa vial be stored?

Refrigerated at 2 to 8 °C, protected from light and labelled with the date and the concentration. Unopened lyophilised vials are kept cold and dark until they are needed.

Work it out for a different vial or concentration

Our peptide calculator opens pre-set for a 10 mg vial with 2 mL of water and marks the 1 mg draw of 20 units on a syringe diagram. Change the vial size, water volume, amount or syringe and it recalculates.

Products: Dihexa 10 mg and bacteriostatic water.

Related reading. What is Dihexa, Dihexa vs Semax, Dihexa vs Cerebrolysin, how to store research peptides and the buying guide.

Sources: McCoy AT et al. Evaluation of metabolically stabilized angiotensin IV analogs as procognitive/antidementia agents. J Pharmacol Exp Ther. 2013. PMID 23055539. Sun X et al. AngIV-analog Dihexa rescues cognitive impairment and recovers memory via the PI3K/AKT signaling pathway. Brain Sci. 2021. PMID 34827486. Martino KA et al. Hepatocyte growth factor/MET activator rescues working memory deficits after repeated mild traumatic brain injury. Neurotrauma Rep. 2025. PMID 42825082. Compound data from PubChem (CID 129010512).

More on this: What Is Dihexa? The Angiotensin IV Analogue and What the Research Showed.