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Protocol

Retatrutide (20 mg Vial)

Complete dosage protocol and reconstitution guide for Retatrutide (20 mg Vial).

Updated November 26, 2025 Research guide Research information only
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Educational reference only. TNHL calculates and organizes user-entered values; it does not diagnose, prescribe, recommend doses, or replace guidance from a qualified professional.
MechanismRetatrutide is a novel triple agonist targeting GLP-1, GIP, and glucagon receptors [1] , studied for substantial weight loss and metabolic improvement in obesity and type 2 diabetes [2] [3] . With an extended half-life of approximately 6 days, this peptide enables convenient once-weekly subcutaneous dosing with a gradual titration protocol to optimize tolerability [1] [4] .
Dosing2–12 mg once weekly (gradual escalation over 12+ weeks).
ReconstitutionAdd 2.0 mL diluent to a 20 mg vial.
StorageLyophilized: freeze at −20 °C (−4 °F) ; after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) and use within 2–4 weeks.

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Run the vial math before tracking.

At 10 mg/mL, 1 unit = 0.01 mL = 0.1 mg on a U-100 insulin syringe.

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01 · At a glance

Quickstart Highlights

Retatrutide is a novel triple agonist targeting GLP-1, GIP, and glucagon receptors [1] , studied for substantial weight loss and metabolic improvement in obesity and type 2 diabetes [2] [3] . With an extended half-life of approximately 6 days, this peptide enables convenient once-weekly subcutaneous dosing with a gradual titration protocol to optimize tolerability [1] [4] .

ReconstituteAdd 2.0 mL bacteriostatic water → 10.0 mg/mL concentration for optimal weekly doses. Typical
Reference dose2–12 mg once weekly (gradual escalation over 12+ weeks).
Easy measuringAt 10 mg/mL, 1 unit = 0.01 mL = 0.1 mg on a U-100 insulin syringe.
StorageLyophilized: freeze at −20 °C (−4 °F) ; after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) and use within 2–4 weeks.
Start with sterile preparation, storage, and injection-site basics before using any calculator output. TNHL is a tracking and education tool only.

02 · Dosing & reconstitution

Dosing & Reconstitution Guide

A practical calculator-ready setup based on the imported protocol reference. Use these values as a math starting point, then verify every entry against your own vial, diluent, and professional guidance.

Standard / Gradual Titration Approach (2 mL = 10.0 mg/mL)

Phase / setup Dose & frequency Volume / units
Weeks 1–42,000 mcg (2 mg)20 units (0.20 mL)
Weeks 5–84,000 mcg (4 mg)40 units (0.40 mL)
Weeks 9–128,000 mcg (8 mg)80 units (0.80 mL)
Weeks 13+12,000 mcg (12 mg)120 units (1.20 mL)

2–12 mg once weekly (gradual escalation over 12+ weeks).

Reconstitution Steps

  1. Draw 2.0 mL bacteriostatic water with a sterile syringe.
  2. Inject slowly down the vial wall; avoid foaming.
  3. Gently swirl/roll until dissolved (do not shake vigorously).
  4. Label with reconstitution date and refrigerate at 2–8 °C (35.6–46.4 °F) , protected from light.
  5. Note: The 20 mg vial size is highly efficient for weekly protocols.

03 · What you'll need

Supplies Needed

Keep this as a planning checklist. TNHL does not sell or verify supplies on this page, and no supplier quality claims are made here.

Peptide Vials Highly efficient vial size for weekly protocols
  • 12 weeks (2→4→8 mg titration): 3 vials
  • 24 weeks (up to 12 mg): 10 vials
  • 48 weeks (maintenance at 12 mg): 25 vials
Insulin Syringes Per week: 1 syringe (once-weekly dosing)
  • 12 weeks: 12 syringes
  • 24 weeks: 24 syringes
  • 48 weeks: 48 syringes
Bacteriostatic Water Use 2.0 mL per vial for reconstitution.
  • 12 weeks (3 vials): 6 mL → 1 × 10 mL bottle
  • 24 weeks (10 vials): 20 mL → 2 × 10 mL bottles
  • 48 weeks (25 vials): 50 mL → 5 × 10 mL bottles
Alcohol Swabs One for the vial stopper + one for the injection site each week.
  • Per week: 2 swabs
  • 12 weeks: 24 swabs → 1 × 100-count box
  • 24 weeks: 48 swabs → 1 × 100-count box
  • 48 weeks: 96 swabs → 1 × 100-count box

Protocol Overview

  • Goal: Achieve substantial weight loss (up to 24% of body weight) and improved metabolic parameters through triple receptor agonism [2] [5] .
  • Schedule: Weekly subcutaneous injections for 12+ weeks with gradual dose escalation.
  • Dose Range: 2–12 mg once weekly; clinical trials tested up to 12 mg as the maximum maintenance dose [1] [3] .
  • Reconstitution: 2.0 mL per 20 mg vial (10.0 mg/mL) provides optimal concentration for weekly dosing with minimal waste.
  • Storage: Lyophilized frozen at −20 °C (−4 °F); reconstituted solution refrigerated at 2–8 °C (35.6–46.4 °F); use within 2–4 weeks.

Dosing Protocol

  • Evidence-based weekly titration approach from clinical trials.
  • Start: 2 mg once weekly for first 4 weeks to establish tolerability [1] [4] .
  • Escalation: Increase to 4 mg weekly (Weeks 5–8), then 8 mg weekly (Weeks 9–12) [1] .
  • Maintenance: 12 mg weekly (Week 13 onward) for maximum efficacy; 8 mg weekly is an alternative maintenance dose [2] .
  • Frequency: Once per week (subcutaneous); consistent day/time recommended.
  • Cycle Length: Minimum 12 weeks for titration; clinical trials extended to 48 weeks showing sustained weight loss [2] .
  • Timing: Any consistent weekly schedule; rotate injection sites each week.

Storage Instructions

  • Proper storage maintains peptide stability and potency.
  • Lyophilized: Store at −20 °C (−4 °F) or colder for long-term preservation; protect from moisture and light [11] [12] .
  • Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F) immediately after mixing; use within 2–4 weeks for maximum potency [11] .
  • Handling: Allow frozen vials to reach room temperature before opening to minimize condensation; never expose reconstituted solution to heat or direct sunlight.
  • Aliquoting: For extended storage beyond 4 weeks, consider freezing unused aliquots; avoid repeated freeze-thaw cycles [12] .

04 · Good to know

Important Notes

  • This Retatrutide page is for educational research organization only.
  • Confirm route, dose, contraindications, monitoring, storage, and cycle decisions with qualified professional guidance.
  • Use sterile technique, rotate sites when applicable, and log missed doses, reactions, and inventory changes.

05 · How it works

How This Works

Retatrutide is a novel triple agonist targeting GLP-1, GIP, and glucagon receptors [1] , studied for substantial weight loss and metabolic improvement in obesity and type 2 diabetes [2] [3] .

With an extended half-life of approximately 6 days, this peptide enables convenient once-weekly subcutaneous dosing with a gradual titration protocol to optimize tolerability [1] [4] .

Reconstitute: Add 2.0 mL bacteriostatic water → 10.0 mg/mL concentration for optimal weekly doses.

The library page pairs that educational context with calculator-ready vial math, so users can understand the protocol structure and then track their own entered values in one place.

06 · Daily habits

Lifestyle Factors

  • Keep meals, training, sleep, and recovery notes in the journal so trends are easier to review.
  • Track body metrics only if they are relevant to the user's goal and approved data sources.
  • Use consistent timing and logging habits so adherence data is meaningful.

07 · What to expect

Potential Benefits & Side Effects

  • Retatrutide observations should be recorded conservatively: expected research endpoints, tolerability notes, injection-site reactions when applicable, sleep, appetite, energy, mood, and any adverse or unusual response.
  • This section is not a claim of therapeutic benefit.

08 · Technique

Injection Technique

Pre-injection preparation
  • Wash hands with soap and water.
  • Wipe the vial stopper and chosen site with alcohol, then let both dry.
  • Confirm the vial concentration, calculator result, and intended draw amount before loading the syringe.
Injection procedure
  • Use the route and needle technique directed by a qualified professional or product instructions.
  • For subcutaneous injections, rotate sites and inject slowly to limit leakage and irritation.
  • Do not reuse needles or syringes.
Post-injection care
  • Dispose of sharps in a puncture-resistant container.
  • Return stored items promptly to the correct temperature.
  • Log dose, site, date, time, inventory change, and any observation.

09 · Evidence

References

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