RetaCalc
Protocol library
SingleInvestigationalPhase 2Sourced

Retatrutide

A triple GIP, GLP-1 and glucagon receptor agonist in phase 3 development. Explore the published phase 2 research arms and vial-aware calculation examples.

Peppys Retatrutide research vial on a neutral background
Product image for vial-size identification. Research use only.

Evidence context, not a personal protocol

Quantities below reproduce study or label context. They do not assess suitability, product equivalence or individual risk.

Published phase 2 design

Weekly research arms

Each line below reconstructs a randomised phase 2 arm. Select a dot to use that assigned quantity in the vial calculation examples.

Study source

Assigned weekly quantities

Select a point for its calculation examples
  1. Weeks 1 to 4
    2 mg
  2. Weeks 5 to 8
    4 mg
    +2 mg after 4 weeks
  3. Weeks 9 to 48
    8 mg
    +4 mg after 4 weeks

Vial-aware arithmetic

20 to 30 unit examples

For the selected 2 mg study quantity, calculate the diluent needed to land at common points on a U-100 scale.

Open the full reverse calculator
Vial quantity

Matches the currently listed Peppys research vial options.

Container capacity check

Use the actual container capacity. This does not confirm solubility or stability.

Draw 20 units
1 mL

calculated diluent

Concentration
10 mg/mL
Container
Fits capacity
Draw 25 units
1.25 mL

calculated diluent

Concentration
8 mg/mL
Container
Fits capacity
Draw 30 units
1.5 mL

calculated diluent

Concentration
6.667 mg/mL
Container
Fits capacity

Formula: diluent mL = vial mg × target units ÷ selected mg ÷ 100. Results are mathematical examples, not preparation instructions.

Regimens studied

Adults with obesity or overweight without diabetes

Once-weekly subcutaneous trial arms targeting 1 mg, 4 mg, 8 mg or 12 mg, with lower starting-dose groups and dose escalation

Phase 2 randomised controlled study over 48 weeks; these were research arms rather than prescribing instructions.

View source

Evidence summary

Retatrutide activates three metabolic hormone receptors and remains an investigational medicine. The strongest published human evidence currently comes from controlled clinical trials.

How to read the studied regimen

The quantities and changes below describe assigned research groups. The published study used once-weekly administration and four-week escalation intervals in groups with a target of 4 mg or more. Select a point to see the corresponding arithmetic, not to choose a personal quantity.

What the vial examples mean

The examples solve for the diluent volume that would place a selected research quantity at 20, 25 or 30 units on a U-100 scale. They do not verify vial capacity, solubility, sterility, stability or whether the labelled vial quantity is accurate. A result that exceeds the selected container capacity is flagged rather than silently rounded.

Safety context

The phase 2 paper should be read in full for participant selection, escalation design, adverse events and discontinuations. Gastrointestinal events were most frequent during escalation, and trial monitoring cannot be reproduced by a calculator.

Warnings and contraindications

Retatrutide is investigational and is not authorised for routine clinical use.
Gastrointestinal adverse events and heart-rate changes were reported in trials.
FDA states that retatrutide has not been found safe and effective for any condition and cannot be used in compounding under US federal law.
Organised research bench with labelled storage tray, vial rack, notebook and thermometer
A clean workspace supports traceability. It does not establish sterility.

Shared across protocols

Supplies and general handling

Keep the universal checklist short. Product-specific labelling and source documentation always take priority over a general guide.

Research vial

Select the labelled vial quantity used in the calculation.

View Peppys vial

Bacteriostatic water

Use only a diluent appropriate to the research method and formulation.

View Peppys BAC water

U-100 measuring syringe

Use a new sterile device for every entry. Source locally.

Source locally

Wipes and sharps container

Plan clean handling and immediate sharps disposal. Source locally.

Source locally

Storage follows the label

Do not apply a universal refrigerator rule. Follow the product, diluent and study documentation for temperature, light and expiry.

Use sterile equipment once

CDC injection-safety guidance calls for a new sterile needle and syringe for each injection and entry into a medication container.

Stability is formulation-specific

Do not infer a post-mixing lifetime from BAC water alone. Discard material when identity, integrity or sterility is in doubt.

General references: CDC injection safety, NHS medicine storage and DailyMed BAC water labelling.