How to Reconstitute Peptides
Reconstitution is dissolving a freeze-dried powder into a solution of a known concentration. The arithmetic is one division, the handling matters more than the maths, and the answer is always a figure in milligrams per millilitre.
What reconstitution is
Almost everything in a vial on this site arrives lyophilised — freeze-dried to a dry powder. That is deliberate: a peptide as dry powder is stable at ordinary temperatures for a long period, while the same peptide in solution is not. Freeze-drying is what makes a peptide shippable at all, and what are peptides covers the chemistry behind it.
Reconstitution reverses it. You add a measured volume of solvent to a known mass of powder, and what you get is a solution whose concentration you know because you chose both numbers.
That is the whole of it. The volume you add does not change how much compound is in the vial — the vial holds what the label says either way. It changes the concentration of what the vial holds, and nothing else.
The solvent: bacteriostatic water, and what it is not
Bacteriostatic water is sterile water containing benzyl alcohol as a bacteriostatic preservative. The preservative is the point: it inhibits bacterial growth in a container that is going to be entered more than once.
Three things it is not, because all three get substituted for it:
| Solvent | Preservative | Why it differs |
|---|---|---|
| Bacteriostatic water | Benzyl alcohol | Inhibits bacterial growth in a container entered repeatedly |
| Sterile water for injection | None | Sterile when sealed, with nothing in it to stay that way once opened |
| Sodium chloride 0.9% | None | Isotonic saline — a different solution chemistry, no preservative |
| Tap or distilled water | None | Not sterile. Not a laboratory solvent. |
We stock bacteriostatic water in 10ml and 30ml, and the peptide supplies page lists it alongside the syringes, pen needles and swabs that go with it. Each starter kit ships with the water already in the box.
The arithmetic, in both directions
One division, and which way round you do it depends on which number you have decided first.
You chose the water volume. What concentration did you get?
concentration = milligrams in the vial ÷ millilitres of water
A 10mg vial with 2ml of water added is 10 ÷ 2 = 5 mg/ml.
You want a particular concentration. How much water?
millilitres of water = milligrams in the vial ÷ the concentration you want
A 30mg vial at a target of 10 mg/ml needs 30 ÷ 10 = 3ml.
The reconstitution calculator does both directions, so you can enter whichever two numbers you have and read off the third.
Worked examples across our vial sizes
Every vial size in the range, against the three water volumes most often used. Read the column you are adding and the row you bought.
| Vial | + 1ml | + 2ml | + 3ml | + 5ml |
|---|---|---|---|---|
| 2mg | 2 mg/ml | 1 mg/ml | 0.67 mg/ml | 0.4 mg/ml |
| 5mg | 5 mg/ml | 2.5 mg/ml | 1.67 mg/ml | 1 mg/ml |
| 10mg | 10 mg/ml | 5 mg/ml | 3.33 mg/ml | 2 mg/ml |
| 20mg | 20 mg/ml | 10 mg/ml | 6.67 mg/ml | 4 mg/ml |
| 30mg | 30 mg/ml | 15 mg/ml | 10 mg/ml | 6 mg/ml |
| 40mg | 40 mg/ml | 20 mg/ml | 13.33 mg/ml | 8 mg/ml |
| 50mg | 50 mg/ml | 25 mg/ml | 16.67 mg/ml | 10 mg/ml |
| 70mg | 70 mg/ml | 35 mg/ml | 23.33 mg/ml | 14 mg/ml |
| 80mg | 80 mg/ml | 40 mg/ml | 26.67 mg/ml | 16 mg/ml |
| 100mg | 100 mg/ml | 50 mg/ml | 33.33 mg/ml | 20 mg/ml |
Two things fall out of that table. A larger vial at the same water volume is a more concentrated solution, not more solution. And the same concentration can be reached from almost any vial by changing the volume — 10 mg/ml is a 10mg vial in 1ml, a 30mg vial in 3ml or a 50mg vial in 5ml.
A blend vial is labelled with the total of its components — the KLOW 80mg vial is 80mg of four compounds combined, not 80mg of one. The division above gives you the total concentration of the blend. The per-component figure is the component's own share of that total, and the product page lists what is in it.
The handling matters more than the maths
The division is trivial. What is not trivial is that peptides are fragile in specific, well-understood ways, and the damage is not visible.
- Let a cold vial reach room temperature first. Adding solvent to glass straight out of a fridge is asking for condensation and a thermal shock neither the powder nor the stopper benefits from.
- Swab the stopper. A sealed vial's stopper is not a sterile surface once it has been handled, and bacteriostatic water inhibits growth rather than sterilising what you introduce. Alcohol swabs are a consumable for a reason.
- Run the solvent down the inside wall of the vial. Do not aim a jet of water at the powder cake. Peptides are degraded by shear, and a stream hitting the cake directly is the most avoidable shear in the whole process.
- Do not shake. Shaking is the single most common way a reconstitution is ruined. It introduces shear and foams the solution — and foam is denatured protein at the air-liquid interface, which is damage you can see. Swirl the vial gently, or set it down and let it dissolve.
- Give it time. A powder cake can take several minutes to go into solution on its own. Patience is not a technique but it replaces several bad ones.
- Look at it. A properly reconstituted solution is clear. Cloudiness, particles that will not disperse, or a cake that refuses to dissolve are all reasons to stop and contact us rather than to keep swirling.
Once it is in solution the storage problem changes completely, and that is the subject of how to store peptides.
What does not need reconstituting
Three formats in the range arrive ready and skip this entire page.
| Format | State on arrival | Reconstitution |
|---|---|---|
| Pens | Already in solution | None |
| Capsules | Finished solid form | None |
| Nasal sprays | Already in solution | None |
| Vials | Lyophilised powder | Required |
If the reconstitution step is the part you would rather not have, those three formats exist precisely because it is a step. A pen and a vial of the same compound are the same compound — retatrutide and tirzepatide are both stocked each way — and BPC-157 capsules vs vials works through what the format choice does and does not change.
What this page does not cover
There is no dose on this page, no protocol, no frequency, no unit conversion and no click count, and there is none anywhere else on this site either.
Everything we supply is an unlicensed research compound. It carries an analytical specification — the compound, the quantity, the purity determined by HPLC — and not a Summary of Product Characteristics. A specification describes what is in a vial. It is not a short leaflet, and publishing a human dose alongside it would be promoting an unlicensed compound for human use. We are not willing to do that, and a calculator that returns millilitres to administer rather than a concentration is the same thing with extra steps.
What we will give you is the chemistry: the concentration arithmetic, in both directions, and the conditions a peptide is stable under. If that is not what you came for, nothing further on the site will help, and are peptides legal in the UK explains the category these compounds sit in.
Supply note. Peptiq supplies research compounds for laboratory research use only. This page covers the handling of a material — concentration, temperature and light. It contains no dosage, protocol or administration guidance of any kind, and we do not publish any.
Frequently asked questions
How do you work out the concentration of a reconstituted vial?
Divide the milligrams in the vial by the millilitres of water added. A 10mg vial with 2ml of bacteriostatic water gives 5 mg/ml. To go the other way, divide the milligrams by the concentration you want: a 30mg vial at 10 mg/ml needs 3ml.
What water do you use to reconstitute a peptide?
Bacteriostatic water — sterile water containing benzyl alcohol as a bacteriostatic preservative. Sterile water for injection and 0.9% sodium chloride contain no preservative, and tap or distilled water is not a laboratory solvent.
Should you shake a vial to dissolve the powder?
No. Shaking introduces shear and foams the solution, and foam at the air-liquid interface is denatured protein. Run the solvent down the inside wall of the vial, swirl gently, and allow several minutes for the cake to dissolve.
Does adding more water mean more compound?
No. The vial holds the quantity on its label whatever volume you add. More water means a lower concentration of the same total amount.
Do you publish dosage information?
No. Everything we supply is an unlicensed research compound for laboratory research use only. We publish concentration arithmetic and handling conditions, and no dosage, protocol, frequency or unit conversion anywhere on the site.