Last medically reviewed: 2026-04-27 by GLP3 Planner editorial. References inline (PubMed / NEJM citations as available).
Quick Answer: How to Reconstitute Retatrutide (GLP-3)
To reconstitute retatrutide, referred to in peptide communities as GLP-3, add bacteriostatic (BAC) water to the vial of lyophilized powder. For a 10mg vial, adding 1mL of BAC water gives a concentration of 10mg/mL (10 units = 1mg on a U-100 syringe). Adding 2mL gives 5mg/mL (20 units = 1mg). Inject the water slowly down the inside wall of the vial, gently swirl until dissolved, and refrigerate at 36-46°F.
Formula: Concentration = Vial mg / Water mL. Then: Units on syringe = (Desired dose mg / Concentration) x 100.
Key Takeaways
- Standard concentration: Mix 10mg retatrutide with 2-3mL BAC water for easy dosing
- Injection technique: Add water slowly down the vial wall, never directly onto powder
- Mixing method: Gently swirl (never shake) until fully dissolved
- Storage: Refrigerate at 36-46°F (2-8°C) for up to 28-60 days
- Use our free calculator to determine exact insulin units for your dose
⚠️ Investigational Drug: Retatrutide is NOT FDA-approved and is currently only available through clinical trials or compounding pharmacies. FDA approval is expected in 2027. For all access options, see how to get retatrutide. This guide is for educational purposes only.
What is Reconstitution?
Reconstitution is the process of adding bacteriostatic water (BAC water) to freeze-dried (lyophilized) peptide powder to create an injectable solution. Compounded retatrutide typically comes as a white powder in a sealed vial that must be reconstituted before use.
Pre-filled pens won't be available until FDA approval. With compounded retatrutide, you need to:
- Calculate how much BAC water to add for your desired concentration
- Properly mix the solution without damaging the peptide
- Store the reconstituted solution correctly
- Calculate the right volume (in insulin units) for each dose
Our free reconstitution calculator handles all the math for you. Just enter your vial size, water volume, and desired dose.
What You'll Need
Required Supplies
- ✓ Retatrutide vial (lyophilized powder, typically 5mg, 10mg, or 15mg)
- ✓ Bacteriostatic water (BAC water): contains 0.9% benzyl alcohol as preservative
- ✓ Insulin syringes (U-100, 0.5mL or 1mL with fine gauge needle)
- ✓ Alcohol swabs (70% isopropyl alcohol)
Optional but Recommended
- ○ Larger mixing syringe (3mL) for adding BAC water
- ○ Sharps container for safe needle disposal
- ○ Clean workspace with good lighting
- ○ Vial labels to mark reconstitution date and concentration
⚠️ Do NOT use: Sterile water or saline without preservative. These lack the benzyl alcohol that prevents bacterial growth. Always use bacteriostatic water for multi-dose vials.
How Much BAC Water for Retatrutide (By Vial Size)
The right amount of bacteriostatic water depends on your vial size and your dosing preferences. Smaller water volumes give a more concentrated solution (fewer units per dose). Larger water volumes are easier to measure precisely on insulin syringes. The table below shows the most common BAC water amounts used by experienced users for each vial size.
| Retatrutide Vial | Recommended BAC Water | Resulting Concentration | Example: 2mg dose |
|---|---|---|---|
| 5mg vial | 0.5mL (concentrated) or 1mL (standard) | 10 mg/mL or 5 mg/mL | 20 units or 40 units |
| 10mg vial | 2mL (most common) | 5 mg/mL | 40 units |
| 15mg vial | 1.5mL (concentrated) or 3mL (standard) | 10 mg/mL or 5 mg/mL | 20 units or 40 units |
| 20mg vial | 2mL (concentrated) or 4mL (easier dosing) | 10 mg/mL or 5 mg/mL | 20 units or 40 units |
| 30mg vial | 3mL | 10 mg/mL | 20 units |
| 60mg vial | 3mL (concentrated) or 6mL (standard) | 20 mg/mL or 10 mg/mL | 10 units or 20 units |
How to read this table: The "Recommended BAC Water" column shows the volume that gives the cleanest dosing math on a U-100 insulin syringe. For non-standard doses, the free reconstitution calculator works out the exact units for any vial size, water volume, and target dose combination.
Common Questions About BAC Water Amounts
Does more BAC water make the retatrutide weaker?
No, the total milligrams in the vial stays the same. More BAC water just spreads the same amount of peptide across more liquid, so each unit on your syringe contains less peptide. This makes precise dosing easier on a U-100 syringe but means each dose takes more units of liquid.
Can I add too much BAC water?
Practically yes, vials only hold about 3mL safely, and beyond that you risk overflow. Most users stay between 1mL and 3mL per 10mg of peptide. Using more than 3mL means dose volumes may exceed 100 units (1mL) and require multiple injections per dose.
Is the BAC water amount different for compounded vs research peptide retatrutide?
No, the math is identical. The vial label states the milligrams of retatrutide, and the BAC water you add determines concentration regardless of source. The same table above applies to both compounded retatrutide from a pharmacy and research-grade peptide.
Retatrutide Reconstitution Calculator
Get the exact BAC water volume and insulin units for any vial size and target dose.
Before mixing, use our calculator to determine the right BAC water volume and how many insulin units equal your desired dose.
Free Reconstitution Calculator
Enter your vial size, BAC water volume, and desired dose to get exact insulin units.
Quick Reference: Common Concentrations
| Vial Size | BAC Water | Concentration | 2mg Dose | 4mg Dose |
|---|---|---|---|---|
| 10mg | 1mL | 10mg/mL | 20 IU | 40 IU |
| 10mg | 2mL | 5mg/mL | 40 IU | 80 IU |
| 10mg | 3mL | 3.33mg/mL | 60 IU | 120 IU |
| 15mg | 3mL | 5mg/mL | 40 IU | 80 IU |
| 30mg | 3mL | 10mg/mL | 20 IU | 40 IU |
IU = insulin units on a U-100 syringe (100 IU = 1mL). Use our calculator for custom concentrations.
Step-by-Step Reconstitution Instructions
Prepare Your Workspace
Wash your hands thoroughly. Gather all supplies on a clean, flat surface with good lighting. Allow the vial and BAC water to reach room temperature if refrigerated.
Clean the Vial Tops
Wipe the rubber stopper of both the retatrutide vial and BAC water vial with an alcohol swab. Let the alcohol dry completely (about 10-15 seconds) before proceeding.
Draw the BAC Water
Using a syringe, draw the calculated amount of BAC water. For a 10mg vial, 2-3mL is typical. Pull back the plunger slightly to add air first, inject air into the BAC water vial, then withdraw the water.
⚠️ Inject Water SLOWLY Down the Vial Wall
This is the most critical step. Insert the needle into the retatrutide vial and angle it so the tip touches the glass wall. Inject the BAC water very slowly, letting it run down the side of the vial, not directly onto the powder.
Direct force on the powder can damage the peptide structure and reduce potency. A slow, gentle stream preserves the retatrutide's integrity.
Gently Swirl to Dissolve
Never shake the vial. Gently swirl it in a circular motion to help the powder dissolve. You can also let it sit for a few minutes and swirl again. The solution should become clear with no visible particles.
Dissolution typically takes 1-5 minutes. If cloudiness persists after 10 minutes of gentle swirling, contact your supplier.
Label and Store
Write the reconstitution date, concentration, and expiration date on the vial. Store immediately in the refrigerator at 36-46°F (2-8°C).
Video Tutorial
Watch this step-by-step demonstration of peptide reconstitution and injection technique by Dr. Jason Emer:
Video covers: supplies needed, sterile technique, BAC water injection, mixing, and subcutaneous injection demonstration.
Storage After Reconstitution
✓ Do This
- • Store in refrigerator at 36-46°F (2-8°C)
- • Keep away from light (store in box if possible)
- • Use within 28-60 days of reconstitution
- • Inspect for particles before each use
- • Always swab the stopper before drawing
✗ Never Do This
- • Never freeze reconstituted retatrutide
- • Don't leave at room temperature for extended periods
- • Don't use if solution is cloudy or has particles
- • Don't use past the expiration date
- • Never share vials or needles
Stability note: While some sources cite 60-day stability, 28 days is the more conservative recommendation for compounded peptides. Potency may decrease over time even with proper storage. The retatrutide storage calculator turns your reconstitution date into a discard-by date and tells you how many days are left.
Common Mistakes to Avoid
❌ Spraying water directly onto the powder
High-pressure streams can denature (damage) the peptide. Always aim for the vial wall and let the water run down gently.
❌ Shaking the vial
Vigorous shaking creates foam and can damage the peptide structure. Gentle swirling is all that's needed.
❌ Using sterile water instead of BAC water
Sterile water has no preservative, so bacteria can grow in multi-dose vials. BAC water's benzyl alcohol prevents contamination.
❌ Leaving reconstituted vial at room temperature
Peptides degrade faster at higher temperatures. Refrigerate immediately after mixing and between uses.
❌ Reusing needles
Reused needles become dull, cause more pain, and increase infection risk. Use a new sterile needle for each injection.
Ready to Calculate Your Dose?
Use our free calculator to get exact insulin units for your retatrutide concentration.
Medical Disclaimer
This guide is for educational and informational purposes only. It does not constitute medical advice, professional diagnosis, or treatment recommendations. Retatrutide is an investigational drug not yet approved by the FDA. Compounded peptides are not FDA-regulated and may vary in quality and purity. Always consult with a qualified healthcare provider before using any medication. Self-administration of injectable medications carries risks including infection, incorrect dosing, and adverse reactions.
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