How Much Bacteriostatic Water for a Cagrilintide 10 mg Vial?
Weight Loss & Metabolism Research
A 10 mg vial of cagrilintide 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.
Cagrilintide 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.
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.
View product →Concentration by water volume
Concentration is the quantity in the vial divided by the water 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.
| Vial | Bacteriostatic water added | Concentration | Units containing 1 mg |
|---|---|---|---|
| 10 mg cagrilintide | 1 mL | 10 mg/mL | 10 units |
| 10 mg | 2 mL | 5 mg/mL | 20 units |
| 10 mg | 3 mL | 3.33 mg/mL | 30 units |
| 10 mg | 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 | 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 |
At 10 mg/mL, which the same vial gives with 1 mL of water, every volume in the table moves in proportion: a 1 mg draw measures 10 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.
Cagrilintide is supplied by Vistara Labs as a lyophilised material for research use. The quantities on this page illustrate the arithmetic of dilution and measurement only.
The cagrilintide vial
Cagrilintide is a long-acting, lipidated analogue of amylin, the 37-amino-acid satiety hormone made by the pancreatic beta cells alongside insulin. A fatty-acid chain attached to the peptide extends its half-life to 159 to 195 hours in a 2021 Phase 1b study (Enebo et al., Lancet, 2021). Vistara Labs supplies it as a 10 mg lyophilised vial. The same 10 mg arithmetic covers the tirzepatide 10 mg vial. Certificates of analysis for the catalogue are published on the Lab Results page.
Cagrilintide’s best-known research partner is semaglutide: the pairing, known as CagriSema, combines the amylin and GLP-1 satiety pathways, and in a 68-week Phase 3 trial of 3,417 adults it produced a 20.4% mean weight reduction against 3.0% with placebo (Garvey et al., N Engl J Med, 2025). The full trial record, from the 2021 Phase 2 monotherapy study onward, is in What is cagrilintide?, and the contrast with a dual-agonist molecule is in Cagrilintide vs Tirzepatide.
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 cagrilintide 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 and bacteriostatic water vs sterile water.
How much bacteriostatic water for 10 mg cagrilintide?
A 10 mg cagrilintide vial is commonly reconstituted with 2 mL of bacteriostatic water, which gives 5 mg/mL; 1 mL gives 10 mg/mL, 3 mL gives 3.33 mg/mL and 5 mL gives 2 mg/mL. At 5 mg/mL each 0.1 mL of solution contains 0.5 mg, and the table shows the same figure for each volume.
| 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 |
| 3 mL | 3.33 mg/mL | 0.33 mg |
| 5 mL | 2 mg/mL | 0.2 mg |
For any other volume, the calculator on this page works out the concentration.
Frequently asked questions
How much bacteriostatic water do I add to a 10 mg vial of cagrilintide?
There is no single correct volume. With 2 mL of bacteriostatic water a 10 mg vial of cagrilintide gives 5 mg/mL; with 1 mL it gives 10 mg/mL. Adding more water does not change the quantity in the vial, it spreads it through a larger volume, so write the concentration you chose on the vial.
How many 10 mg vials does one vial of bacteriostatic water cover?
One multi-dose vial of bacteriostatic water covers several research vials. Check that the peptide vial has headspace for the volume before choosing a larger one.
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 should reconstituted cagrilintide look like?
Properly reconstituted cagrilintide 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 cagrilintide 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.
How much bac water for a 10 mg cagrilintide vial?
A 10 mg cagrilintide vial is commonly reconstituted with 2 mL of bacteriostatic water, which gives 5 mg/mL; 1 mL gives 10 mg/mL. At 5 mg/mL each 0.1 mL (10 units on a U-100 syringe) contains 0.5 mg.
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: Cagrilintide 10 mg and bacteriostatic water.
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.
