BPC-157 Reconstitution — Volume and Concentration Table

Published 2026-09-28 · Lyophile Editorial

Reconstitution math for BPC-157 reduces to one relationship: concentration equals mass divided by diluent volume. Everything else — syringe units, aliquot volumes, draw sizes — is derived from that number. The table comes first, then the arithmetic behind each row, so you can plan a batch without re-deriving anything by hand.

For research use only — not clinical guidance.

BPC-157 reconstitution table — standard vial sizes

The table below assumes lyophilized BPC-157 (free acid or acetate salt, both commonly supplied as a 5 mg or 10 mg fill) and a U-100 insulin syringe, where 1 unit = 0.01 mL.

| Vial mass | Diluent added | Concentration (mcg/mL) | Concentration (mg/mL) | mcg per U-100 unit | mL per 250 mcg | |---|---|---|---|---|---| | 5 mg | 1 mL | 5,000 | 5.0 | 50 | 0.05 mL (5 units) | | 5 mg | 2 mL | 2,500 | 2.5 | 25 | 0.10 mL (10 units) | | 5 mg | 2.5 mL | 2,000 | 2.0 | 20 | 0.125 mL (12.5 units) | | 5 mg | 5 mL | 1,000 | 1.0 | 10 | 0.25 mL (25 units) | | 10 mg | 2 mL | 5,000 | 5.0 | 50 | 0.05 mL (5 units) | | 10 mg | 3 mL | 3,333 | 3.33 | 33.3 | 0.075 mL (7.5 units) | | 10 mg | 5 mL | 2,000 | 2.0 | 20 | 0.125 mL (12.5 units) | | 10 mg | 10 mL | 1,000 | 1.0 | 10 | 0.25 mL (25 units) |

Read the "mcg per unit" column as your working constant. Once you know a 5 mg vial in 2 mL gives 25 mcg per unit, every subsequent draw is a division problem you can do in your head.

How do you calculate peptide concentration after reconstitution?

Concentration in mcg/mL equals total peptide mass in micrograms divided by total diluent volume in milliliters. A 5 mg fill is 5,000 mcg; add 2 mL of diluent and you get 5,000 ÷ 2 = 2,500 mcg/mL. Per USP <1163>, pharmaceutical calculations of this type are expected to be shown with units carried through, which is why every row above lists both mcg/mL and mg/mL.

The step-by-step for any vial:

1. Convert mass to micrograms. 1 mg = 1,000 mcg. A 5 mg vial = 5,000 mcg.
2. Measure diluent volume in mL. Use a graduated syringe or a volumetric pipette, not a "fill to the shoulder" estimate.
3. Divide mass by volume. 5,000 mcg ÷ 2 mL = 2,500 mcg/mL.
4. Convert to per-unit. Divide mcg/mL by 100 (because 1 mL = 100 U-100 units). 2,500 ÷ 100 = 25 mcg per unit.
5. Invert for draw volume. Target mass ÷ concentration = volume. 250 mcg ÷ 2,500 mcg/mL = 0.10 mL = 10 units.

Step 4 is where most planning errors happen. A U-100 syringe is calibrated so that 100 units occupy 1.00 mL — that is the definition of the U-100 scale, and it is why the conversion factor is exactly 100 and not 10 or 1,000. U-40 and U-50 syringes exist and use different scales; mixing them into a U-100 calculation produces a tenfold or twofold error.

How much bacteriostatic water for a 5 mg vial?

A 5 mg BPC-157 vial reconstituted with 2 mL of bacteriostatic water yields 2,500 mcg/mL, or 25 mcg per unit on a U-100 syringe. Bacteriostatic water for injection, described in USP <797> as sterile water containing 0.9% benzyl alcohol as a preservative, is the standard diluent when a multi-draw vial is planned; sterile water for injection contains no preservative and is intended for single-use preparation.

Two practical constraints on the volume you choose:

• Vial headspace. A typical 3 mL lyophilization vial holds roughly 3.5–4 mL total. Adding 5 mL of diluent to a 3 mL vial will not fit. Check the nominal vial size printed on the label before committing to a large diluent volume.
• Draw precision. Larger diluent volumes give finer per-unit resolution but require larger draws. Smaller volumes concentrate the solution and push you toward sub-5-unit draws, where the graduation marks on many U-100 syringes are 1 unit apart but the printed barrel accuracy is coarser.

There is no universally "correct" diluent volume. There is only the concentration that makes your intended draw land on a readable graduation.

What does 250 mcg look like on a U-100 syringe?

250 mcg of a 2,500 mcg/mL solution occupies 0.10 mL, which is 10 units on a U-100 insulin syringe. The arithmetic is 250 ÷ 2,500 = 0.1 mL, and 0.1 mL × 100 units/mL = 10 units. At 5,000 mcg/mL the same 250 mcg is 5 units; at 1,000 mcg/mL it is 25 units.

That spread — 5 units to 25 units for the same mass — is the entire reason concentration planning matters. A 5-unit draw sits close to the zero mark on a 1 mL U-100 barrel, where graduation crowding and dead-space in the hub both matter more. A 25-unit draw lands in the comfortable middle of the scale.

A common failure mode: reading the barrel from the wrong end. U-100 insulin syringes are marked with the zero at the needle hub and count up toward the plunger, opposite to how many people intuitively read a graduated cylinder. Confirm orientation on a dry syringe before drawing anything.

Diluent volume vs. draw resolution

| Target draw | At 5,000 mcg/mL | At 2,500 mcg/mL | At 1,000 mcg/mL | |---|---|---|---| | 100 mcg | 2 units | 4 units | 10 units | | 250 mcg | 5 units | 10 units | 25 units | | 500 mcg | 10 units | 20 units | 50 units | | 1,000 mcg | 20 units | 40 units | 100 units (full 1 mL barrel) |

The bottom-right cell is the practical ceiling: a 1,000 mcg draw from a 1,000 mcg/mL solution fills an entire 1 mL U-100 barrel. If your planned draw exceeds 100 units, either increase concentration or switch to a larger syringe with an appropriate scale.

Reconstitution procedure — the plain-English steps

1. Bring both the lyophilized vial and the diluent to room temperature before opening. Condensation on a cold vial can wick moisture past a stopper.
2. Swab the stopper with 70% isopropyl alcohol and let it air-dry. USP <797> requires disinfection of the closure before any penetration.
3. Draw the diluent volume you calculated. If you are adding 2 mL, draw 2 mL — not "about 2 mL."
4. Inject slowly down the inside wall of the vial rather than onto the powder cake. Direct streams can denature peptide at the impact point.
5. Do not shake. Swirl or roll the vial until the cake dissolves completely. A hazy solution is not fully reconstituted.
6. Record the concentration on the label: mass, diluent volume, mcg/mL, and date. The label is the only reliable record once the original packaging is discarded.

Batch planning — working backward from a draw

If you know the draw volume you want to work with, solve for diluent instead of concentration. Diluent volume equals total mass divided by the concentration you need.

Want 250 mcg in a clean 10-unit draw (0.10 mL)? That requires 2,500 mcg/mL. For a 5 mg vial: 5,000 mcg ÷ 2,500 mcg/mL = 2 mL. For a 10 mg vial: 10,000 ÷ 2,500 = 4 mL.

The 10 mg / 4 mL combination is a useful default for planning because it lands at 2,500 mcg/mL — the same working concentration as the 5 mg / 2 mL row, with double the total draws per vial.

Where to source bacteriostatic water

• BAC Water Depot — bacteriostatic water for injection, 0.9% benzyl alcohol, multi-vial packs.
• Med Lab Supply — sterile diluents and lab consumables, US-shipped.
• Farris Labs — bacteriostatic and sterile water options for research use.

Where to source research peptides

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped.
• Peptide Sciences — published COAs, research-grade lyophilized peptides.
• Limitless Life Nootropics — third-party tested peptide inventory.

For research use only — not clinical guidance. All figures above are arithmetic derived from stated masses and volumes; verify your own vial fill and diluent specification against the supplier's published documentation before planning a batch.