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Retatrutide · reconstitution math · research use only

Retatrutide reconstitution is a titration-ladder problem, not a fixed-concentration one.

Most peptide reconstitution questions have one answer: add X mL of bacteriostatic water to the vial, set a working concentration, and draw the same volume every time. Retatrutide is different. The Phase 2 clinical titration ladder runs from roughly 2 mg all the way to 12 mg per week, so the concentration and draw volume that work cleanly at a low dose can produce either a very small or a very large draw at the high end — depending on what BAC water volume you chose at reconstitution. This page works through the dilution math for multiple concentration scenarios so researchers can model which one keeps draw volumes tractable across the full escalation ladder. All figures are reproduced strictly as a laboratory dilution reference, not a human-use protocol. Titan does not stock standalone tirzepatide or semaglutide — retatrutide ($199.99) is the in-catalog triple-agonist GLP compound.

Retatrutide — $199.99Retatrutide dosage reference

Choose a BAC water volume for the ladder, not just one dose

At 2 mg/mL working concentration (achieved by adding 1 mL bacteriostatic water to a 2 mg vial, or 5 mL to a 10 mg vial), a 2 mg weekly dose draws exactly 1 mL — straightforward. But a 12 mg dose at the same concentration draws 6 mL, an impractical single injection volume. By contrast, a 10 mg/mL concentration (1 mL into a 10 mg vial) draws only 0.12 mL for a 1.2 mg dose — too small for accurate measurement on a U-100 syringe. The reconstitution decision locks the working concentration for the whole vial, so it is worth modelling the full dose range before adding water.

Run the calculator →

Worked example at 4 mg/mL

For a vial specified as 10 mg lyophilized retatrutide, adding 2.5 mL bacteriostatic water yields 4 mg/mL. On a U-100 insulin syringe (1 mL barrel, 100 units = 1 mL), every 10 units equals 0.1 mL. At 4 mg/mL: a 2 mg dose = 0.5 mL (50 units); a 4 mg dose = 1.0 mL (100 units, full syringe); an 8 mg dose = 2.0 mL (two full syringes); a 12 mg dose = 3.0 mL (three). That is a wide but workable range — the draw volumes scale linearly once concentration is fixed. Adjust the numbers to the actual stated mass of the vial you are working with.

Full titration ladder →

Bacteriostatic water vs sterile water

Retatrutide reconstituted in plain sterile water has no preservative, and the vial must typically be discarded within 24–48 hours. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth and extends the usable window to roughly 28 days refrigerated. For a compound dosed once weekly, a 28-day refrigerated window usually covers 3–4 draws from one vial. This distinction is handled in detail on the dedicated shelf-life page.

Shelf-life and storage reference →

Shelf life after reconstitution

The Phase 2 protocol for retatrutide used once-weekly subcutaneous dosing. If a 10 mg vial is reconstituted at 4 mg/mL, a researcher modelling the 2 mg starting dose draws 0.5 mL and the remaining 1.5 mL stays in the vial — roughly 3 more 0.5 mL draws over the following 3 weeks, comfortably within a 28-day BAC-water window. Concentration choice therefore also determines how many draws the shelf-life window allows. The shelf-life calculator page works through the detailed storage math.

Storage and shelf-life →

Verify the sequence and fatty-acid modification

Retatrutide is a 39-amino-acid peptide with a C18 fatty-acid modification at Lys26 via a gamma-glutamic acid and mini-PEG linker. That acylation makes it distinct from both tirzepatide (dual GIP/GLP-1 agonist, C18 diacid at Lys34) and semaglutide (mono GLP-1, C18 diacid at Lys26 of a 31-mer). A certificate of analysis for retatrutide should confirm the full 39-residue sequence by mass spectrometry and, ideally, the intact acylated species — not just a purity figure on what may be the unacylated backbone.

How to read a COA →

Research-use framing

These calculations reproduce the dilution arithmetic for retatrutide as a laboratory reference for researchers modelling in-vitro work — not instructions for human use. Retatrutide is an investigational compound; Titan supplies it as a research-use-only reagent and makes no therapeutic, metabolic, or weight-management claim. Nothing here is medical or dosing advice. Confirm your own vial's stated mass and run the numbers before any in-vitro modelling.

Research-use policy →

The detail, in plain terms

Retatrutide reconstitution: the dilution math in one table.

The key variable is concentration choice: it sets draw volumes for every dose level on the titration ladder and determines how many draws fit inside the BAC-water shelf-life window. Work through these numbers before adding water to a vial.

Compound
Retatrutide — 39-residue GIP/GLP-1/glucagon triple agonist with C18 fatty-acid acylation at Lys26.
Reconstitution solvent
Bacteriostatic water (0.9% benzyl alcohol) preferred; extends shelf life to ~28 days refrigerated vs ~24-48 h with plain sterile water.
Example concentration A
2 mg vial + 1 mL BAC water = 2 mg/mL. Draws: 1 mg→0.5 mL, 2 mg→1.0 mL, 4 mg→2.0 mL.
Example concentration B
10 mg vial + 2.5 mL BAC water = 4 mg/mL. Draws: 2 mg→0.5 mL, 4 mg→1.0 mL, 8 mg→2.0 mL, 12 mg→3.0 mL.
U-100 syringe note
100 units = 1.0 mL on a standard insulin syringe. At 4 mg/mL: 50 units = 2 mg, 100 units = 4 mg.
COA check
Full 39-residue sequence by MS + acylated species confirmation + HPLC purity. Purity alone is not sufficient for an acylated peptide.
Titan catalog
Retatrutide lyophilized vial, $199.99 — research use only, not for human or animal consumption.

Questions researchers ask

Before you order.

How do you reconstitute retatrutide?
Add bacteriostatic water (0.9% benzyl alcohol) to the lyophilized vial and swirl gently — do not shake, as vigorous agitation can degrade the acylated peptide. The key decision is how much water to add: the volume you choose sets the working concentration (mg/mL) for the entire vial and therefore determines your draw volume at every dose level on the titration ladder. These figures are reproduced as a laboratory dilution reference, not a human protocol.
What concentration should I use for retatrutide?
It depends on the dose levels you are modelling. At 4 mg/mL (2.5 mL BAC water into a 10 mg vial), draw volumes scale from 0.5 mL (2 mg) to 3.0 mL (12 mg) — a tractable range that covers most of the titration ladder. A 2 mg/mL concentration (5 mL into 10 mg) produces larger draws and is easier to measure accurately at low doses but reaches 6 mL for a 12 mg dose, which may be impractical. Model the full dose range before reconstituting.
How long does reconstituted retatrutide last?
Reconstituted in bacteriostatic water (0.9% benzyl alcohol), the accepted research window is approximately 28 days refrigerated at 2–8 °C, away from light. Reconstituted in plain sterile water (no preservative), the recommendation is to discard within 24–48 hours. Never freeze a reconstituted vial. The dedicated shelf-life page covers the storage requirements in full.
What is the difference between retatrutide reconstitution and BPC-157 or TB-500 reconstitution?
The unit scale and draw volumes differ substantially. BPC-157 is typically dosed in micrograms (200–500 mcg), so you are drawing very small volumes (often 0.1–0.5 mL) at low mg/mL concentrations. TB-500 is dosed in milligrams (2–10 mg per week), and retatrutide is also dosed in milligrams (2–12 mg per week). However, the escalating titration ladder for retatrutide means concentration choice has a bigger impact on practical draw volumes across the full dose range than it does for the fixed-dose TB-500 protocol.
Why does retatrutide need a fatty-acid modification confirmed on the COA?
Retatrutide has a C18 fatty-acid chain attached to Lys26 via a gamma-glutamic acid and mini-PEG linker. This acylation is what extends its half-life to approximately six days by promoting albumin binding. The unacylated backbone is a different molecule with a different pharmacological profile. A purity figure from HPLC alone may not distinguish the acylated from the unacylated species if the chromatographic method is not tuned for it; mass spectrometry confirming the intact acylated species provides better assurance.
Does Titan sell retatrutide?
Yes. Retatrutide is an in-stock lyophilized vial at $199.99, supplied for research use only and not for human or animal consumption. It is the only triple-agonist GIP/GLP-1/glucagon compound in the Titan catalog. Titan does not stock tirzepatide (dual agonist) or semaglutide (mono agonist) — comparison pages for those compounds direct to the in-stock retatrutide.

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