RetaCalc
Protocol library
StackInvestigationalMixedVery Low confidenceSourced

Retatrutide and cagrilintide

A commonly discussed investigational pairing without a controlled human combination regimen. This page records the evidence gap and does not propose stack quantities.

Evidence context, not a personal protocol

Quantities below reproduce their stated source context—label, human study, laboratory work or educational guide. They do not assess suitability, product equivalence or individual risk.

Community-reported schedule

Community-reported · not a validated schedule

Community dose schedule

A community retatrutide base titrated 2-12 mg once weekly, with cagrilintide added low (0.25-0.5 mg) on an opposing day. The planner tracks the subcutaneous retatrutide arm only; community reports, not a validated combination schedule.

Evidence source
Reported maximum quantity
Retatrutide titration (forum)
Choose the maximum quantity reported by this community line. Any earlier phase can be selected below for its arithmetic.

Assigned weekly quantities

Select a point for its calculation examples
  1. Retatrutide base
    2 mg
    Retatrutide arm only; cagrilintide is added separately and low (~0.25-0.5 mg) on a day opposing the retatrutide shot.
  2. Weeks 5 to 8
    4 mg
    +2 mg
    Reports titrate retatrutide over roughly four weeks per step; cagrilintide is titrated up separately as needed.
  3. Weeks 9 to 12
    6 mg
    +2 mg
  4. Weeks 13 to 16
    9 mg
    +3 mg
  5. Weeks 17 to 24
    12 mg
    +3 mg
    Top of the reported retatrutide range; cagrilintide is often used as-needed rather than every week.

Vial-aware arithmetic

Reconstitution examples, up to 3 mL

Choose the vial quantity and BAC water first. The diagram and results below update for the selected 2 mg reported quantity. Higher-strength vials may naturally land outside the 20-30 unit band.

Vial quantity

Choose the quantity printed on the vial.

BAC water added

Use 1, 2 or 3 mL, or enter a custom volume up to 3 mL.

Open the full reverse calculator
Three millilitre research vial, diluent vial and capped U-100 syringe on an ink-blue surface
One small vial, one measured diluent volume and one U-100 scale. The arithmetic connects all three.
BAC water selected
1 mL

Basic example limit: 3 mL maximum. Check the actual vial and product-specific limits.

1 mL BAC
20 units

resulting U-100 draw

Concentration
10 mg/mL
BAC added
1 mL

Shown in the diagram. Closest of these examples to 25 units.

2 mL BAC
40 units

resulting U-100 draw

Concentration
5 mg/mL
BAC added
2 mL
3 mL BAC
60 units

resulting U-100 draw

Concentration
3.333 mg/mL
BAC added
3 mL

Formula: draw units = selected mg × BAC mL ÷ vial mg × 100. The 20-30 unit band is a measurement reference, not a recommendation. Results are mathematical examples, not preparation instructions.

Dosage and protocol evidence

Each card states what the quantities are based on. A third-party or animal schedule is not a validated human dose.

Human StudySubcutaneousOnce weekly
Separate retatrutide monotherapy research

Phase 2 retatrutide arms evaluated once-weekly targets from 1 mg to 12 mg with study-specific starts and escalation

These quantities describe retatrutide alone. They do not supply a retatrutide-plus-cagrilintide stack formula.

View source
Human StudySubcutaneousOnce weekly
Separate cagrilintide monotherapy research

Phase 2 cagrilintide arms evaluated 0.3 mg, 0.6 mg, 1.2 mg, 2.4 mg and 4.5 mg once weekly

These quantities describe cagrilintide alone. Adding them to a retatrutide schedule has not been validated in a controlled human study.

View source
Evidence Gap
Combined stack evidence

No controlled human retatrutide-plus-cagrilintide dose or escalation schedule was identified

The absence is the protocol result. Separate monotherapy maxima cannot establish combined exposure, tolerability or safety.

View source
Community GuideSubcutaneous in reportsUsually once weekly
online research community combination reports

Examples include 12 mg retatrutide plus 0.6 mg cagrilintide weekly, or adding 0.125-0.25 mg cagrilintide weekly during retatrutide titration

These are uncontrolled community combinations, not evidence that the monotherapy programmes can be combined safely. The archive documents no controlled human trial of the pairing; dosing-summaries/01-retatrutide.md:62-66.

View source
Community GuideSubcutaneous in reportsOnce weekly, on opposing days
authenticated research-forum (Peppys) retatrutide-plus-cagrilintide reports

A retatrutide base of about 2-12 mg once weekly (commonly titrated 2-4-6-9 or 3-6-9 mg over roughly four weeks per step) is paired with cagrilintide added low, about 0.125-0.5 mg and titrated upward, dosed the same as semaglutide and usually pinned on a day opposing the retatrutide shot; some use cagrilintide only as-needed rather than every week. Reported combinations include 10-12 mg retatrutide with 0.5-1 mg cagrilintide

Forum provenance from an authenticated archive with usernames and post numbers omitted. There is no controlled human trial of the pairing; response to cagrilintide is bimodal and combined use is associated with heavier fatigue and, in one report, raised liver enzymes. Retatrutide and cagrilintide are given as separate subcutaneous injections and are community provenance, not a validated combination regimen.

View source

Evidence summary

Each component has monotherapy data, but that does not answer combination questions. Overlapping effects can change tolerability and risk in ways that arithmetic cannot predict.

Why no schedule is shown

No adequate controlled human combination study was identified. Community reports are insufficient to establish a regimen, so RetaCalc does not infer one.

Community provenance (Peppys)

An authenticated research-forum archive describes pairing a retatrutide base of roughly 2-12 mg once weekly with cagrilintide added low, about 0.125-0.5 mg and titrated upward, with the two typically injected on opposing days. Cagrilintide is said to be dosed like semaglutide and is sometimes used only as-needed; response to it is bimodal, and the combination is linked in reports to heavier fatigue and, in one case, raised liver enzymes. Reported quantities conflict, no controlled human trial of the pairing exists, and usernames and post numbers are omitted. The planner above tracks only the retatrutide arm and reproduces the arithmetic of these reported quantities; it does not validate the combination.

Warnings and contraindications

No controlled human combination regimen was identified for this pairing.
Separate monotherapy trials cannot establish combined safety, efficacy or tolerability.
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.