PT-141 Reconstitution Calculator

Mixing PT-141: What to Know Before You Reconstitute

1. 01

   Bacteriostatic water vs. sterile water

   Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth after the vial has been punctured. Sterile water has no preservative and is generally treated as single use. For a compound used occasionally across an extended period, bacteriostatic water is the conventional choice, since the vial will sit in the refrigerator between draws rather than being consumed steadily.

2. 02

   How much water to add

   Water volume changes concentration, not content. A 10 mg vial holds 10 mg whether you add 1 mL or 3 mL. PT-141 doses fall in the milligram range, so draws are larger than with microgram peptides, and the concentration you choose determines whether a dose fits comfortably in the syringe.

   Vial	Water	Concentration	Per unit	1 mg draw	2 mg draw
   5 mg	1 mL	5.0 mg/mL	50 mcg	20 units	40 units
   5 mg	2 mL	2.5 mg/mL	25 mcg	40 units	80 units
   10 mg	2 mL	5.0 mg/mL	50 mcg	20 units	40 units
   10 mg	3 mL	3.33 mg/mL	33.3 mcg	30 units	60 units

   Because a vial is often not finished before its discard window closes, the water volume decision here carries a consideration the other compounds do not have: a more concentrated mix produces smaller draws but leaves more unused solution behind when the window arrives. Some people mix less water for that reason. The calculator above shows the doses per vial figure, which is the number that makes this trade visible.

3. 03

   Mixing technique

   Angle the needle so the water runs down the inside wall of the vial rather than onto the powder directly, then swirl gently or let it stand until dissolved. Do not shake. The finished solution should be clear with no visible particles, and a vial that stays cloudy after gentle swirling is one most people will not use.

4. 04

   Storage before and after mixing

   Unopened lyophilized vials keep cool and dark. Once mixed, the vial is refrigerated and the same roughly 28 day convention applies, drawn from the discard window for punctured bacteriostatic water. This is the step that matters most with PT-141 specifically. On an occasional use pattern, weeks can pass between draws, and the vial's expiration is governed by the date it was mixed rather than by how much is left in it. Writing the mix date on the vial, or letting PepKit count it down, is the difference between knowing and guessing when a vial has been sitting for a month.

5. 05

   The syringe

   U-100 insulin syringes, where 100 units equal 1 mL and each unit is 0.01 mL. Milligram doses produce draws in the twenties to forties of units at common concentrations, so the 1 mL 100 unit syringe is the usual choice, though a 0.5 mL syringe can hold most doses at higher concentrations.

6. 06

   Common mistakes worth avoiding

   The recurring ones: losing track of when a vial was mixed because draws are far apart, assuming a vial is still good because it is still mostly full, mixing more water than the use pattern justifies and discarding most of the vial, confusing mg and mcg in conversion, and reusing a previous unit count after mixing a new vial at a different volume.