Retatrutide Reconstitution & Dosing Guide

Exactly how much bacteriostatic water to use for a 10 mg retatrutide vial, the U-100 syringe math for clean dosing, and refrigerated storage that keeps the peptide stable for up to 28 days. For research use only.

Quick answer

10 mg retatrutide + 2 mL bacteriostatic water = 5 mg/mL. On a U-100 insulin syringe, every 10 units (0.1 mL) draws 500 mcg. Store upright in the refrigerator at 2–8 °C and use within 28 days. Do not freeze once reconstituted.

Reconstitution Steps (10 mg vial)

Gather Materials

Retatrutide 10 mg lyophilized vial, bacteriostatic water (0.9% benzyl alcohol), U-100 insulin syringe (29–31 gauge, ½ inch), alcohol swabs, and a sharps container. Work on a clean, disinfected flat surface.

Choose Your Concentration

Most common for a 10 mg retatrutide vial: 2 mL BAC water → 5 mg/mL (5,000 mcg/mL). Each '10 units' on a U-100 syringe = 0.1 mL = 500 mcg. Alternative: 1 mL BAC water → 10 mg/mL for smaller draws; 4 mL → 2.5 mg/mL for very low starting research doses.

Swab Both Vial Stoppers

Wipe the rubber stoppers on both the retatrutide vial and the BAC water vial with a fresh alcohol swab. Let alcohol evaporate for 5–10 seconds before any needle insertion.

Draw the BAC Water

Insert a U-100 syringe into the BAC water vial, invert, and draw your chosen volume (e.g. 2.0 mL = 200 units across multiple draws if needed). Tap to clear air bubbles and expel any excess back into the BAC water vial.

Add Water Slowly Down the Vial Wall

Angle the needle so the stream of BAC water runs gently down the inside wall of the retatrutide vial. Never spray directly onto the lyophilized cake — high-velocity impact can shear peptide bonds and foam the solution.

Swirl, Don't Shake

Let the vial sit undisturbed for 60–90 seconds, then gently swirl in a slow circular motion until the powder fully dissolves. The finished solution should be clear and colorless. Discard any vial that is cloudy or contains particulates.

Label and Refrigerate

Write the reconstitution date and final concentration (e.g. '5 mg/mL — opened 06/28') on the vial. Store upright at 2–8 °C (refrigerator, not freezer). Use within 28 days for best stability.

BAC Water Ratios & U-100 Dosing

Reconstitution	Per 10 units	Per 5 units	Best for
10 mg / 1 mL BAC (10 mg/mL)	1,000 mcg (1 mg)	500 mcg	Smallest draws, but the least forgiving — easy to over-pull on a U-100 syringe.
10 mg / 2 mL BAC (5 mg/mL)	500 mcg	250 mcg	Most popular ratio for retatrutide research — clean math, comfortable draw volumes.
10 mg / 4 mL BAC (2.5 mg/mL)	250 mcg	125 mcg	Best for low starting research doses (e.g. titration studies beginning at 250 mcg).

U-100 reference: 100 units = 1.0 mL. 10 units = 0.1 mL. 1 unit = 0.01 mL.

Storage of Reconstituted Retatrutide

Stage	Temperature	Duration	Notes
Unopened lyophilized vial	2–8 °C refrigerated, or up to 25 °C short-term	Until labeled expiration	Keep boxed and away from direct light. Tolerates brief shipping excursions thanks to lyophilization.
Reconstituted, in use	2–8 °C refrigerator	Up to 28 days	Always upright, away from the freezer compartment. The 0.9% benzyl alcohol in BAC water suppresses microbial growth.
Long-term storage of unopened vial	−20 °C freezer	Up to 24 months	Optional for inventory holds. Bring fully to room temperature before reconstituting to avoid condensation inside the vial.
Reconstituted, freezer	Not recommended	—	Freeze–thaw cycles shear peptide chains and reduce activity. Reconstitute only what you'll use within 28 days.

Common Mistakes to Avoid

❌ Don't: Shake the vial to dissolve faster

Shaking creates foam and shear forces that denature retatrutide. Always swirl gently or let it dissolve passively.

❌ Don't: Spray BAC water directly onto the powder cake

Direct impact damages peptide bonds. Aim the stream against the inside wall so water trickles down onto the cake.

❌ Don't: Freeze reconstituted retatrutide

Ice crystal formation physically cleaves peptide bonds. One freeze-thaw can measurably reduce activity.

❌ Don't: Use sterile water instead of BAC water for multi-dose vials

Sterile water has no preservative. For a vial that will be punctured multiple times over weeks, you need the 0.9% benzyl alcohol in BAC water.

❌ Don't: Reconstitute without writing the date on the vial

Retatrutide is stable ~28 days reconstituted. Without a label, you lose track of where you are in that window.

❌ Don't: Pull doses from a cloudy or particulate-containing solution

Cloudiness indicates aggregation or contamination. Discard the vial and reconstitute a fresh one.

Retatrutide Reconstitution FAQ

How much bacteriostatic water do I use for a 10 mg retatrutide vial?

Most researchers use 2 mL of bacteriostatic water for a 10 mg retatrutide vial, producing a 5 mg/mL solution. On a U-100 insulin syringe, every 10 units (0.1 mL) equals 500 mcg. For smaller titration doses use 4 mL (2.5 mg/mL); for the smallest draw volumes use 1 mL (10 mg/mL).

How do I store reconstituted retatrutide?

Store reconstituted retatrutide upright in a refrigerator at 2–8 °C (35–46 °F), away from the freezer compartment and direct light. Properly reconstituted with bacteriostatic water containing 0.9% benzyl alcohol, it remains stable for up to 28 days. Do not freeze reconstituted retatrutide — freeze-thaw cycles damage the peptide.

Can I use sterile water instead of bacteriostatic water for retatrutide?

Only for a single-use research scenario. Sterile water contains no preservative, so any vial punctured more than once should use bacteriostatic water (0.9% benzyl alcohol), which inhibits microbial growth over the 28-day in-use window.

How long is retatrutide stable after mixing?

Retatrutide reconstituted with bacteriostatic water and stored at 2–8 °C is typically stable for up to 28 days. Discard any vial that becomes cloudy, discolored, or develops particulates before 28 days.

What size syringe should I use for retatrutide?

A U-100 insulin syringe (29–31 gauge, ½ inch) with 0.5 mL or 1.0 mL capacity is standard. The fine markings (1 unit = 0.01 mL) allow accurate measurement at 5 mg/mL — for example, 5 units = 250 mcg, 10 units = 500 mcg, 20 units = 1 mg.

Does retatrutide need to be refrigerated before reconstitution?

Unopened lyophilized retatrutide is best stored at 2–8 °C refrigerated, though it tolerates brief room-temperature excursions during shipping. For long-term inventory (months+), it can be stored at −20 °C. Always allow the vial to return to room temperature before reconstituting to prevent condensation inside the vial.

Why must I swirl and not shake the vial?

Retatrutide is a chain of amino acids held together by peptide bonds. Shaking introduces shear forces and creates foam, both of which can denature the molecule. Gentle swirling — or simply waiting 60–90 seconds — fully dissolves the lyophilized cake without damaging the peptide.

Related Retatrutide Resources

Retatrutide Research Guide →Semaglutide vs Retatrutide →GLP-1 Comparison →Bacteriostatic Water →General Reconstitution Guide →Peptide Calculator →

Retatrutide is sold strictly For Research Use Only. Not for human or veterinary use, diagnosis, or treatment.