ARA-290 Reconstitution: How Much Bacteriostatic Water
A 10 mg vial of ARA-290 reconstituted with 2 mL of bacteriostatic water gives a concentration of 5 mg/mL; with 1 mL it gives 10 mg/mL. The calculation depends only on the quantity in the vial and the volume of water added, so the figures below apply to any 10 mg vial.
There is no single correct volume. Adding more water does not change how much is in the vial. It spreads the same quantity through a larger volume, which changes how many syringe units correspond to a given amount. The tables on this page use volumes that produce round numbers on a U-100 syringe; other volumes work identically as long as the resulting concentration is written on the vial.
Peptide 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.
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 ARA-290?
A 10 mg ARA-290 vial is commonly reconstituted with 2 mL of bacteriostatic water, which gives 5 mg/mL; 1 mL gives 10 mg/mL, 4 mL gives 2.5 mg/mL and 5 mL gives 2 mg/mL. At 5 mg/mL each 0.1 mL of solution contains 0.5 mg.
| Water added | Concentration | Amount in 0.1 mL (10 units on a U-100 syringe) |
|---|---|---|
| 1 mL | 10 mg/mL | 1 mg |
| 2 mL | 5 mg/mL | 0.5 mg |
| 4 mL | 2.5 mg/mL | 0.25 mg |
| 5 mL | 2 mg/mL | 0.2 mg |
For any other volume, the calculator on this page works out the concentration. 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 0.5 mg is 0.5 divided by 5, which is 0.1 mL, or 10 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 | 0.05 mL | 5 units |
| 0.5 mg | 0.1 mL | 10 units |
| 1 mg | 0.2 mL | 20 units |
| 2 mg | 0.4 mL | 40 units |
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.
ARA-290 is described here as a lyophilised material for laboratory research use only. The quantities on this page illustrate the arithmetic of dilution and measurement only.
The ARA-290 vial
ARA-290 is commonly supplied in research catalogues as a 10 mg lyophilised vial. Vistara Labs does not currently stock ARA-290, but you can request it: contact us and we will source it for you. The calculator on this page works for any vial. The compounds we do carry are listed in the peptide library.
What ARA-290 is
ARA-290, also known as cibinetide, is a nonerythropoietic peptide engineered from the structure of erythropoietin. It interacts selectively with the innate repair receptor, which mediates tissue protection, without the red-cell effects of erythropoietin. Its human research centres on small nerve fibre loss.
- In a randomised, double-blind pilot trial in 22 people with sarcoidosis and small fibre neuropathy, ARA-290 improved small fibre neuropathy screening scores at week 4 compared with placebo, with no safety concerns raised (Heij et al., 2012).
- In a phase 2 study in type 2 diabetes with painful neuropathy, ARA-290 improved haemoglobin A1c and lipid profiles over 56 days and significantly improved neuropathic symptom scores (Brines et al., 2015).
- In a phase 2b trial of 64 people with sarcoidosis-associated small nerve fibre loss, cibinetide increased corneal nerve fibre area and regenerating nerve fibres in the skin at day 28 (Culver et al., 2017).
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.
Why the solution should look clear
Properly reconstituted ARA-290 forms a clear, colourless solution. Cloudiness, strands or a gel that will not disperse usually mean the water went in too fast or the vial was shaken; 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 bac water for a 10 mg ARA-290 vial?
A 10 mg ARA-290 vial is commonly reconstituted with 2 mL of bacteriostatic water, which gives 5 mg/mL; 5 mL gives 2 mg/mL. At 5 mg/mL each 0.1 mL (10 units on a U-100 syringe) contains 0.5 mg.
How many units on a U-100 syringe contain 0.5 mg at 5 mg/mL?
At 5 mg/mL (a 10 mg vial with 2 mL of water), the volume that contains 0.5 mg is 0.5 divided by 5, which is 0.1 mL, or 10 units. Units are millilitres multiplied by 100, so 0.1 mL is 10 units. The amounts on this page illustrate the arithmetic only.
What should reconstituted ARA-290 look like?
Properly reconstituted ARA-290 forms a clear, colourless solution. Cloudiness, strands or a gel that will not disperse usually mean the water went in too fast or the vial was shaken; haze that appears later points to warm or bright storage. More on the causes in why peptides gel or go cloudy.
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. Details in bacteriostatic water explained.
How should a reconstituted ARA-290 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. The full storage guide is how to store research peptides.
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 0.5 mg draw of 10 units on a syringe diagram. Change the vial size, water volume, amount or syringe and it recalculates.
For any vial: bacteriostatic water.
Sources: Heij L et al. Safety and efficacy of ARA 290 in sarcoidosis patients with symptoms of small fiber neuropathy: a randomized, double-blind pilot study. Mol Med. 2012. PMID 23168581. Brines M et al. ARA 290, a nonerythropoietic peptide engineered from erythropoietin, improves metabolic control and neuropathic symptoms in patients with type 2 diabetes. Mol Med. 2015. PMID 25387363. Culver DA et al. Cibinetide Improves Corneal Nerve Fiber Abundance in Patients With Sarcoidosis-Associated Small Nerve Fiber Loss and Neuropathic Pain. Invest Ophthalmol Vis Sci. 2017. PMID 28475703.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
