Follistatin-344 Reconstitution: How Much Bacteriostatic Water
A 1 mg vial of Follistatin-344 reconstituted with 1 mL of bacteriostatic water gives 1000 mcg/mL; with 2 mL it gives 500 mcg/mL. The calculation depends only on the quantity in the vial and the volume of water added, so the figures below apply to any 1 mg vial. A 1 mg vial holds 1000 mcg, and this page works in mcg because the amounts involved are small.
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 1 mg Follistatin-344?
A 1 mg Follistatin-344 vial is commonly reconstituted with 1 mL of bacteriostatic water, which gives 1000 mcg/mL; 0.5 mL gives 2000 mcg/mL and 2 mL gives 500 mcg/mL. At 1000 mcg/mL each 0.1 mL of solution contains 100 mcg.
| Water added | Concentration | Amount in 0.1 mL (10 units on a U-100 syringe) |
|---|---|---|
| 0.5 mL | 2000 mcg/mL | 200 mcg |
| 1 mL | 1000 mcg/mL | 100 mcg |
| 2 mL | 500 mcg/mL | 50 mcg |
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 1000 mcg/mL (a 1 mg vial with 1 mL of water), the volume that contains 100 mcg is 100 divided by 1000, 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 1000 mcg/mL | U-100 units |
|---|---|---|
| 20 mcg | 0.02 mL | 2 units |
| 50 mcg | 0.05 mL | 5 units |
| 100 mcg | 0.1 mL | 10 units |
| 200 mcg | 0.2 mL | 20 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.
Follistatin-344 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 Follistatin-344 vial
Follistatin-344 is commonly supplied in research catalogues as a 1 mg lyophilised vial. Vistara Labs does not currently stock Follistatin-344, 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 Follistatin-344 is
Follistatin is an activin-binding protein that also blocks myostatin, a negative regulator of skeletal muscle mass. FS344 is an alternatively spliced form of follistatin, and it is the form chosen for human gene-delivery trials.
- Follistatin blocked myostatin binding to its activin type II receptor, and animal models engineered to express high levels of follistatin in muscle showed large increases in muscle mass (Lee and McPherron, 2001).
- In a phase 1/2a trial in Becker muscular dystrophy, FS344 delivered by gene transfer to the quadriceps improved six-minute walk distance in four of six participants, with reduced fibrosis and a more normal fibre size distribution on biopsy (Mendell et al., 2015).
- In sporadic inclusion body myositis, FS344 gene transfer improved six-minute walk distance by a median of 56 m a year, against a decline of 25.8 m a year in matched untreated participants (Mendell 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 Follistatin-344 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 1 mg Follistatin-344 vial?
A 1 mg Follistatin-344 vial is commonly reconstituted with 1 mL of bacteriostatic water, which gives 1000 mcg/mL; 2 mL gives 500 mcg/mL. At 1000 mcg/mL each 0.1 mL (10 units on a U-100 syringe) contains 100 mcg.
How many units on a U-100 syringe contain 100 mcg at 1000 mcg/mL?
At 1000 mcg/mL (a 1 mg vial with 1 mL of water), the volume that contains 100 mcg is 100 divided by 1000, 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 Follistatin-344 look like?
Properly reconstituted Follistatin-344 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 Follistatin-344 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 1 mg vial with 1 mL of water and marks the 100 mcg 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: Lee SJ, McPherron AC. Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci U S A. 2001. PMID 11459935. Mendell JR et al. A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther. 2015. PMID 25322757. Mendell JR et al. Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes. Mol Ther. 2017. PMID 28279643.
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.
