How to reconstitute a peptide blend (and split it into units)

A blend vial holds more than one peptide, freeze-dried together into a single cake. There is still only one water volume to choose. What changes is the bookkeeping: the vial carries as many concentrations as it has components, locked to each other in the ratio the manufacturer set before the powder was dried. This is general information about mechanics and arithmetic, not medical advice.

What is actually inside a blend vial

Blends are co-lyophilized: the components are weighed out, combined in solution and dried together, so the cake is homogeneous and every microlitre drawn later carries all of them in the same proportion. That proportion is a property of the vial, and water cannot move it.

Which makes the label the first thing to settle. A vial marked 10 mg can mean 10 mg of peptide in total, split across the components, or 10 mg of each. Both get called a 10 mg blend by somebody: read one as the other and every mark on the barrel carries twice, or half, what was calculated.

A well-labelled blend states each component separately and then the sum — for instance four peptides listed one by one and then an 80 mg total. If the label gives one number and no breakdown, the per-component concentration cannot be derived, and no calculator can invent the missing figures. That is a reason to ask the supplier, not to assume the split is even.

How to reconstitute peptide blend vials, step by step

The method is the same as any lyophilized vial. Two steps carry the extra weight, and both come before the first puncture.

• Write each component's milligrams down, then the total. Everything after this is division on those numbers.
• Bring the vial to room temperature — ten to fifteen minutes out of the fridge.
• Fix the water volume first, and check the glass will hold it. Water cannot be taken back out, and a 3 ml vial has no room for 5 ml. Bacteriostatic water carries 0.9% benzyl alcohol as a preservative, which is what makes repeated entries workable; plain sterile water carries none.
• Swab both stoppers with fresh alcohol wipes and let them dry.
• Measure it with a syringe graduated in millilitres. A U-100 barrel is the wrong instrument for one to four millilitres.
• Run the stream down the inside wall rather than onto the cake.
• Swirl, never shake, and give it longer than a single-peptide vial: components do not all dissolve at the same rate. Wait until nothing is left on the glass.
• Inspect against white paper. Colour is not automatically a fault — a copper peptide in the blend makes the solution blue — but cloudiness or visible solids is a reason to stop.
• Label the glass with the date of first puncture and the per-component concentration, not only the total. The total is the number that misleads you a fortnight later.

One water volume, several concentrations

Once it is liquid the rest is division, run once per component. One mark on a U-100 barrel is 0.01 ml — always, whatever is dissolved in it.

Purely as an example, to run the maths: a 1:1 vial holding 5 mg of each peptide, 10 mg in total, taking 2 ml of water. The solution is 5 mg/ml of peptide overall and 2.5 mg/ml of each component, so one mark holds 25 mcg of each. Eight marks hold 200 mcg of each, and 400 mcg of peptide altogether. The same vial in 1 ml holds 50 mcg of each per mark, and that same 200 mcg lands on four marks instead of eight.

When the ratio is not 1:1

Uneven blends are common, and they are where a total-only label does the most damage. Take an 80 mg vial: 50 mg of one peptide and 10 mg of each of three others, a 5:1:1:1 split. In 4 ml of water the solution is 20 mg/ml overall, but that figure is useless on its own: the first component sits at 12.5 mg/ml and the other three at 2.5 mg/ml each. One mark therefore holds 125 mcg of the first and 25 mcg of each of the rest; ten marks hold 1.25 mg, and 0.25 mg three times over.

None of that is a recommendation: it is the same division done four times, redone for every vial and every water volume. That conversion is what the Vialog calculator runs, so it is not done by hand, component by component, at two in the morning. What to administer comes from a qualified healthcare professional.

Storage, and the clocks

Dry is the stable state, which is why the blend was freeze-dried at all. Once mixed, refrigerate at 2 to 8 °C, in the body of the fridge rather than the door, and do not freeze it.

Then the clocks run, and the shortest one wins. Bacteriostatic water for injection is labelled for use within 28 days of first puncture, and that clock starts at the puncture, not when the vial begins to run low. Each peptide has its own stability in solution, and a blend keeps only as long as its least durable component. Write the date on the glass, and the concentrations next to it.

Frequently asked

Does a blend vial labelled 10 mg contain 10 mg of each peptide?

Not necessarily, and the difference is a factor of two or more. Some suppliers label the total mass across all components; others label each component and leave the reader to add them up, so a 5 mg + 5 mg vial and a 10 mg + 10 mg vial can both end up described as a 10 mg blend. If the breakdown is not on the label, the per-component concentration cannot be calculated from what you have.

Can you add more water to change one peptide in a blend?

No. Water changes the concentration of every component by the same factor, because they are all dissolved in the same liquid. Doubling the water halves each one; it never shifts the balance between them. The ratio was fixed when the components were weighed and dried together, and it is the one number in a blend that cannot be edited afterwards.

How many units are drawn from a 5 mg + 5 mg blend reconstituted in 2 ml?

As arithmetic: 5 mg of each in 2 ml is 2.5 mg/ml of each, so one mark on a U-100 barrel holds 25 mcg of each component. An amount of 200 mcg of each therefore lands on eight marks, and that single draw carries 400 mcg of peptide in total. The amount itself is set by a clinician; this only places it on the barrel.

Is a co-lyophilized blend the same as mixing two vials together?

They are different objects. A blend was combined and dried by the manufacturer at a stated ratio, and its handling instructions describe that mixture. Two finished solutions combined at home produce something neither label describes: the ratio is whatever the two draws happened to be, and every transfer is another entry through a stopper.

How long does a reconstituted peptide blend keep in the fridge?

The practical limit is usually the water: bacteriostatic water for injection is labelled for use within 28 days of the first puncture. Beyond that, a blend is governed by its least stable component rather than by an average of them. Keep it at 2 to 8 °C, out of the fridge door, never frozen, and date the glass at the moment the stopper is first pierced.

Keep reading: How to reconstitute a peptide · How many units do I draw?.