How to Reconstitute Retatrutide

You've got a vial of retatrutide — a triple-receptor agonist targeting GIP, GLP-1, and glucagon receptors — and it arrived as a freeze-dried powder. Before you can use it, you need to reconstitute it with bacteriostatic water.

This guide walks you through the entire process: mixing, measuring doses across the escalation protocol, and storing your peptide so nothing degrades.

What You Need

Before you start, gather everything:

• Retatrutide lyophilized vial (typically 5mg or 10mg)
• Bacteriostatic water (BAC water) — not sterile water, not saline
• Insulin syringes — 1mL (100 unit), 29-31 gauge
• Alcohol swabs — for cleaning vial tops
• A clean, flat workspace

Why bacteriostatic water? It contains 0.9% benzyl alcohol that prevents bacteria from growing in your solution. Regular sterile water has no preservative, so the vial must be used within 24 hours. Since retatrutide is dosed once weekly and a single vial spans multiple weeks, BAC water is essential — it gives you up to 28 days refrigerated.

Step-by-Step Reconstitution

Step 1: Clean Everything

Wipe the tops of both vials (retatrutide and BAC water) with alcohol swabs. Let them air dry for 10 seconds. This prevents contamination — skip it at your own risk.

Step 2: Draw Your Bacteriostatic Water

Using a fresh insulin syringe, draw your desired amount of BAC water. The amount you add determines your concentration (see the dilution charts below).

For most people, 2mL into a 5mg vial is the sweet spot. It gives clean, round numbers across the entire dose escalation range from 0.5mg through 2.5mg.

For 10mg vials — common if you're running a longer protocol or escalating to higher doses — 2mL still works well, giving you a higher concentration that keeps injection volumes manageable at 8-12mg doses.

Step 3: Add Water to the Peptide Vial

Insert the needle into the retatrutide vial at an angle, aiming at the glass wall — not directly at the powder. Let the water trickle down the side of the vial gently.

Do not squirt water directly onto the powder. Peptides are fragile proteins. Aggressive mixing can damage the molecular structure and reduce potency.

Step 4: Let It Dissolve

Gently swirl the vial with a slow rotating motion. Do not shake it. The powder should dissolve within 1-2 minutes into a perfectly clear, colorless solution.

If particles remain after 5 minutes of gentle swirling, the peptide may be degraded. A properly manufactured retatrutide dissolves easily.

Step 5: Store Correctly

Refrigerate immediately at 36-46F (2-8C). The reconstituted solution is stable for up to 28 days with bacteriostatic water.

Dilution Charts

Why 2mL? For 5mg vials, it keeps your starting dose (0.5mg) at a measurable 20 units and your mid-range doses (1-2mg) well within syringe range. For 10mg vials, 2mL gives you a concentrated solution that keeps even 8-12mg doses under 100 units.

The Math (So You Can Do It Yourself)

Here's the formula for any vial size and any amount of water:

Concentration = Peptide Amount (mcg) / Water Added (mL)

Then to find your injection volume:

Units to inject = Desired Dose (mcg) / Concentration (mcg/mL) x 100

Example: 5,000mcg vial + 2mL water = 2,500mcg/mL. For a 1mg (1,000mcg) dose: 1,000 / 2,500 x 100 = 40 units.

For higher doses from a 10mg vial: 10,000mcg + 2mL = 5,000mcg/mL. For a 12mg (12,000mcg) dose: 12,000 / 5,000 x 100 = 240 units — you'd need multiple draws or more water. At 4mL: 2,500mcg/mL, so 12mg = 480 units. Consider splitting into two injection sites for volumes above 1mL.

Don't want to do math? Use our Reconstitution Calculator — plug in your vial size, water amount, and desired dose, and it does the rest.