Retatrutide Pen Dosage Protocol

Quick Start

The short version

If you only read one thing, read this. The four cards below are the whole protocol in plain English — the sections that follow just add the detail.

Dosage Chart

Handling

Dosing & Reconstitution Guide

The pen is pre-filled — no reconstitution required. Attach a fresh pen needle, prime the pen, dial the target dose, and inject subcutaneously.

Subcutaneous Protocol

Frequency: once weekly subcutaneously. Slow uptitration reduces GI adverse effects.

Supplies Needed

Plain-English Glossary

Jargon, translated

A quick decoder for the terms you'll see across this page.

Subcutaneous (subQ)

Injected into the fatty layer just under the skin — not into muscle or vein. Easier and less painful than an IM shot.

Reconstitution

Mixing a dry powder with liquid (bacteriostatic water) to turn it into an injectable solution.

Lyophilized

Freeze-dried. The peptide arrives as a dry powder so it stays stable during shipping.

Bacteriostatic water

Sterile water with a tiny amount of preservative that prevents bacteria growth — used to mix peptides.

Units (on an insulin syringe)

The small tick marks on a U-100 syringe. 100 units = 1 mL. Most doses are just a few units.

Half-life

How long it takes your body to clear half of a dose. Guides how often you inject.

Titration

Starting low and slowly increasing the dose so your body can adjust.

Protocol Overview

• Goal: Support metabolic research on multi-receptor incretin signaling.
• Schedule: Once weekly subcutaneous injection.
• Dose range: 2–12 mg, titrated slowly.
• Storage: Refrigerated, protected from light.

Dosing Protocol

• Start: 2 mg once weekly for four weeks.
• Titrate in ~2 mg increments every 4 weeks if tolerated.
• Timing: Consistent day of the week.
• Cycle length: 12–24 weeks, then reassess.

Storage Instructions

• Lyophilized product: room temperature, sealed and protected from light. Refrigeration acceptable.
• Reconstituted product: 2–8 °C (35.6–46.4 °F) refrigerated, protected from light.
• Do not freeze reconstituted solution.
• Allow to reach room temperature before administration to reduce injection-site response.

Important Notes

• Use a new sterile syringe for each administration.
• Rotate injection sites (abdomen, thighs, upper arms) to reduce local irritation.
• Discard the vial if the solution becomes cloudy, discolored, or shows particulates.
• Document daily dose and site rotation for consistency.
• GI effects are dose-dependent — slow titration is the primary mitigation.

Mechanism

How This Works

Potential Benefits & Side Effects

• Substantial reductions in body weight in phase-2 trials.
• Improved glycemic parameters in type-2 diabetes research.
• Reduced hepatic steatosis markers reported.
• Common adverse effects: nausea, diarrhea, constipation.

Lifestyle Factors

• Prioritize protein and resistance training to preserve lean mass.
• Stay well hydrated.
• Avoid high-fat meals near injection day.
• Maintain consistent injection day for adherence.

Injection Technique

1. 1. Attach a fresh pen needle and prime the pen.
2. 2. Clean the injection site with alcohol.
3. 3. Dial the target dose.
4. 4. Pinch a skinfold; insert at 45–90° subcutaneously.
5. 5. Depress fully, hold 5–10 seconds, withdraw.
6. 6. Dispose of the pen needle in a sharps container.

References

1. 1

   Jastreboff et al., NEJM (2023)

   Retatrutide phase-2 trial in obesity

   View source
2. 2

   Coskun et al. (2022)

   Triple-agonist pharmacology

   View source