How to Reconstitute Peptides: Step-by-Step Guide with Dosage Calculator
Bacteriostatic water, insulin syringes, and the exact math for calculating your dose
Reconstituting peptides means dissolving lyophilized (freeze-dried) powder in bacteriostatic water to create an injectable solution. The process takes 2 minutes but requires precise technique to avoid degrading the peptide. This guide covers everything: what to buy, how to reconstitute, how to calculate your dose, and how to store it correctly.
Most therapeutic peptides are sold as lyophilized (freeze-dried) powder in sterile vials. Before use, they must be reconstituted — dissolved into a sterile liquid — to create an injectable solution. This is the step most new peptide users find intimidating, but it's straightforward once you understand the process.
The stakes matter: improper reconstitution degrades the peptide (wasting expensive material), and non-sterile technique creates infection risk. This guide covers everything correctly.
What You Need
| Item | Purpose | Where to Get |
|---|---|---|
| Bacteriostatic water (BAC water) | The reconstitution solvent. Contains 0.9% benzyl alcohol to prevent bacterial growth in the multi-use vial. | Amazon, pharmacy, peptide suppliers |
| Insulin syringes (U-100, 1 mL) | For drawing and injecting. The U-100 markings let you measure in units (1 unit = 0.01 mL), which is the standard for peptide dosing. | Pharmacy (no Rx required in most states), Amazon |
| Alcohol swabs | To sterilize vial tops and injection site before every use. | Pharmacy, Amazon |
| Peptide vials | Your lyophilized peptide (e.g., 5 mg BPC-157 vial) | Compounding pharmacy or research chemical supplier |
Do NOT use: Regular sterile water (no preservative — bacteria can grow), saline (can degrade some peptides), or distilled water (not sterile).
Step-by-Step Reconstitution
- Gather supplies — peptide vial, BAC water vial, insulin syringe, alcohol swabs. Work on a clean surface.
- Swab both vial tops — wipe the rubber stopper on both vials with an alcohol swab. Let dry for 15 seconds.
- Draw BAC water into syringe — insert the needle through the BAC water vial stopper at an angle; draw back the plunger to pull in your desired volume (see dose calculator below). Typically 1–2 mL per vial.
- Inject BAC water slowly into peptide vial — insert needle through the peptide vial stopper and drizzle the water slowly down the side of the vial. Do NOT squirt directly onto the powder — this can damage the peptide structure.
- Swirl gently — do not shake — hold the vial between two fingers and gently rotate until the powder is fully dissolved. The solution should become completely clear. Shaking introduces bubbles and can denature the peptide.
- The solution is ready — store in refrigerator immediately. Most reconstituted peptides are stable for 4–6 weeks refrigerated.
Dose Calculation: The Math
This is where most people get confused. The formula is simple once you see it once:
Formula: (Dose in mcg ÷ Total mcg in vial) × Volume of BAC water added (in mL) × 100 = Units to draw on insulin syringe
Example — BPC-157 250 mcg dose:
- Vial contains: 5,000 mcg (5 mg)
- BAC water added: 2 mL
- Desired dose: 250 mcg
- Calculation: (250 ÷ 5,000) × 2 × 100 = 10 units on the syringe
Example — Ipamorelin 200 mcg dose:
- Vial contains: 2,000 mcg (2 mg)
- BAC water added: 2 mL
- Desired dose: 200 mcg
- Calculation: (200 ÷ 2,000) × 2 × 100 = 20 units on the syringe
Tip: Using 1 mL of BAC water makes the math easy for some peptides (every 10 units = 10% of the vial), but 2 mL gives you more precision at small doses and is generally preferred.
Storage and Shelf Life
- Unreconstituted (lyophilized) powder: Refrigerator for months; freezer for 1–2 years. Keep away from light.
- Reconstituted solution: Refrigerator at 36–46°F (2–8°C) for 4–6 weeks. Some peptides (BPC-157, TB-500) are more stable; more sensitive peptides (CJC-1295 without DAC, ipamorelin) should be used within 4 weeks.
- Do not freeze reconstituted peptides — freeze-thaw cycles degrade the solution.
- Discard if: The solution becomes cloudy, changes color, or you see particles. This indicates degradation or contamination.
Injection Technique
Most research peptides are administered subcutaneously (SubQ) — injected into the fatty tissue just below the skin, not into muscle (intramuscular/IM).
- Common injection sites: Abdomen (1–2 inches from navel), outer thigh, or upper arm fat. Rotate sites to avoid lipodystrophy (fat atrophy at injection site).
- Technique: Pinch the skin to lift the fat layer. Insert the needle at a 45-degree angle (or 90 degrees if you have adequate fat). Inject slowly. Release the pinch. Apply gentle pressure with a swab after — don't rub.
- Needle size: 28–31 gauge, 5/16–1/2 inch (8–12 mm). Standard U-100 insulin syringes work perfectly.
Frequently Asked Questions
What is bacteriostatic water and why do I need it?
Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol, which prevents bacterial growth in the vial between uses. Regular sterile water has no preservative, so bacteria can grow after the first needle puncture. For any peptide you'll use over multiple days (which is all of them), BAC water is essential. It's available over the counter at pharmacies and on Amazon.
How much BAC water should I add to a peptide vial?
1–2 mL is the standard. Using 2 mL gives more dosing precision at small mcg doses. The amount of BAC water affects your concentration (mcg per unit on the syringe) but not the total amount of peptide. Use our dose calculator formula above to figure out how many units to draw for your specific dose regardless of how much BAC water you used.
Can I use saline instead of bacteriostatic water?
Not recommended. Normal saline (0.9% NaCl) lacks the benzyl alcohol preservative, so bacteria can grow in the vial between uses. Sterile saline for single-use injection is technically acceptable, but for multi-dose peptide vials, bacteriostatic water is the correct choice. Some peptides (particularly those with specific pH requirements) can also be degraded by saline over time.
How do I know if my peptide is still good?
A good peptide solution is completely clear and colorless (or very slightly tinted for some peptides). Discard if you see cloudiness, particulates, unusual color, or if the solution smells off. Reconstituted peptides stored correctly in a refrigerator are typically stable for 4–6 weeks. When in doubt, discard — peptide vials are inexpensive relative to the risk of injecting a degraded or contaminated product.
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