Reta20

Retatrutide (20 mg Vial) Dosage Protocol

Retatrutide is an investigational triple-receptor agonist peptide (targets GLP-1, GIP, and glucagon receptors) under development for obesity and type 2 diabetes[1][2]. Phase 2 trials demonstrated remarkable weight-loss efficacy, with patients losing up to 24% of body weight at 48 weeks on higher doses[3][4]. This educational protocol presents a once-weekly subcutaneous approach with gradual titration to minimize gastrointestinal side effects.

Reconstitute: Add 2.0 mL bacteriostatic water → ~10.0 mg/mL concentration.
Typical weekly range: 2–8 mg once weekly (gradual escalation over 8–12 weeks).
Easy measuring: At 10.0 mg/mL, 1 unit = 0.01 mL ≈ 100 mcg on a U-100 insulin syringe.
Storage: Lyophilized: freeze at −20 °C (−4 °F); after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) for up to 4 weeks.

Educational guide for reconstitution and weekly dosing

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

Phase	Weekly Dose	Units (per injection) (mL)	Vials Needed
Weeks 1–4	2 mg (2000 mcg)	20 units (0.20 mL)	1 vial per dose
Weeks 5–8	4 mg (4000 mcg)	40 units (0.40 mL)	1 vial per dose
Weeks 9–12	6 mg (6000 mcg)	60 units (0.60 mL)	1 vial per dose
Weeks 13+	8 mg (8000 mcg)	80 units (0.80 mL)	1 vial per dose

Frequency: Inject once weekly subcutaneously[1][2]. All doses ≤12 mg can be drawn from one reconstituted 20 mg vial with 2.0 mL reconstitution. Volumes >1.0 mL may be split into 2 separate subcutaneous injections at different sites to ensure proper absorption[5].

Reconstitution Steps

Draw 2.0 mL bacteriostatic water with a sterile syringe.
Inject slowly down the vial wall; avoid foaming.
Gently swirl/roll until dissolved (do not shake).
Label with date and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
Use within 4 weeks of reconstitution^[16].

Advanced / Aggressive Protocol (2 mL = ~10.0 mg/mL)

Phase	Weekly Dose	Units (per injection) (mL)	Vials Needed
Weeks 1–4	2 mg (2000 mcg)	20 units (0.20 mL)	1 vial per dose
Weeks 5–8	4 mg (4000 mcg)	40 units (0.40 mL)	1 vial per dose
Weeks 9–12	8 mg (8000 mcg)	80 units (0.80 mL)	1 vial per dose
Weeks 13+	12 mg (12000 mcg)	120 units (1.20 mL)	1 vial per dose

Note: The 12 mg dose represents the highest dose tested in Phase 2 trials[3][4], producing maximum weight-loss efficacy (~24% body weight at 48 weeks). All doses ≤12 mg can be drawn from one reconstituted 20 mg vial with 2.0 mL reconstitution. Volumes >1.0 mL should be split into 2 injections at separate sites. Gradual titration is critical to minimize gastrointestinal side effects[6].

Important: This guide is for educational purposes only and is not medical advice. Retatrutide is not FDA-approved and is available only for research use. All dosing must follow trial protocols.

Plan based on a 12–24 week weekly protocol with gradual titration.

Peptide Vials (Retatrutide, 20 mg each):
- 12 weeks (Standard to 6 mg): 3 vials
- 24 weeks (Standard to 8 mg): 8 vials
- 12 weeks (Aggressive to 8 mg): 3 vials

Insulin Syringes (U-100, 1 mL capacity):
- Per week: 1–2 syringes (depending on dose; higher doses require split injections)
- 12 weeks: 12–24 syringes
- 24 weeks: 24–48 syringes

Bacteriostatic Water (10 mL bottles): Use ~2.0 mL per vial for reconstitution.
- 12 weeks (3 vials): 6 mL → 1 × 10 mL bottle
- 24 weeks (8 vials): 16 mL → 2 × 10 mL bottles

Alcohol Swabs: One for the vial stopper + one for each injection site.
- Per week: 2–4 swabs (1 per vial + 1–2 per injection site)
- 12 weeks: ~50 swabs → recommend 1 × 100-count box
- 24 weeks: ~100 swabs → recommend 1 × 100-count box

Concise summary of the once-weekly regimen.

Goal: Support significant weight reduction and metabolic improvements through triple-receptor activation^[1]^[7].
Schedule: Weekly subcutaneous injections for 12–48 weeks (clinical trials ranged 36–48 weeks)^[2].
Dose Range: 2–12 mg weekly with gradual 4-week titration steps^[3]^[4].
Reconstitution: 2.0 mL per 20 mg vial (~10.0 mg/mL) for accurate unit measurements.
Storage: Lyophilized frozen at −20 °C (−4 °F); reconstituted refrigerated at 2–8 °C (35.6–46.4 °F) for up to 4 weeks^[16].

Suggested weekly titration approach from clinical trials.

Start: 2 mg weekly for 4 weeks to assess tolerance^[6].
Escalate: Increase by 2–4 mg every 4 weeks as tolerated.
Target: 6–8 mg weekly (standard); 12 mg weekly (advanced/aggressive).
Frequency: Once per week (subcutaneous), same day each week.
Cycle Length: Minimum 24 weeks; trials extended to 48 weeks^[3]^[4].
Timing: Any consistent day/time; rotate injection sites with each dose.

Proper storage preserves peptide quality and stability.

Lyophilized: Store at −20 °C (−4 °F) or colder in dry, dark conditions; stable for up to 24 months^[16].
Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F); use within 4 weeks^[16].
Allow vials to reach room temperature before opening to reduce condensation.
For extended storage, aliquot reconstituted solution and freeze at −20 °C (−4 °F); thaw only once before use^[17].

Practical considerations for consistency and safety.

Use new sterile insulin syringes for each injection; dispose in a sharps container^[14].
Rotate injection sites (abdomen, thighs, upper arms) systematically to reduce local irritation and lipohypertrophy^[13].
For volumes >1.0 mL, split into 2 separate injections at different sites for better absorption^[5].
Inject slowly; wait a few seconds before withdrawing the needle to ensure full dose delivery.
Document weekly dose, date, and injection sites to maintain consistency.
Gradual titration is essential to minimize gastrointestinal side effects; never skip escalation steps^[6].

Retatrutide’s unique mechanism of action stems from its triple-agonist design. By activating GLP-1 and GIP receptors, it enhances insulin secretion (when glucose is present) and suppresses appetite, similar to existing incretin therapies^[7]^[8]. Additionally, Retatrutide’s glucagon receptor agonism raises metabolic rate and promotes energy expenditure, further amplifying fat burning and weight loss beyond GLP-1/GIP effects alone^[7]. The peptide is engineered with a fatty-acid moiety to extend its circulation time (half-life ~6 days), allowing for once-weekly dosing^[2]. The combined hormonal activation leads to reduced calorie intake, increased satiety, and enhanced lipid oxidation, yielding potent weight loss and glycemic control^[8]^[9]. Preclinical studies confirmed that adding glucagon activity helps counteract the body’s adaptive slowing of metabolism during weight loss^[7]. In essence, Retatrutide tackles three metabolic pathways at once, resulting in greater efficacy in lowering blood glucose and body fat than single- or dual-agonist therapies.

Observations from Phase 2 human clinical trials.

Benefits

Exceptional weight loss: Patients with obesity (without diabetes) lost an average of 22–24% of body weight at 48 weeks on 8–12 mg doses^[3]^[4].
Glycemic control: In type 2 diabetes patients, HbA1c dropped by 1.3–2.0% (from ~8.0% to ~6.0%) with 4–12 mg doses^[1]; ~82% reached HbA1c ≤6.5%.
Cardiometabolic improvements: Reductions in blood pressure, LDL cholesterol, waist circumference, and liver fat content (>80% resolution of hepatic steatosis on high doses)^[10]^[11].
Universal response: 100% of participants on 8–12 mg achieved at least 5% weight reduction^[4].

Side Effects

Gastrointestinal symptoms: Most common adverse effects were mild-to-moderate nausea, vomiting, and diarrhea, occurring primarily during dose escalation^[6]^[12].
Side effects were dose-dependent and transient; gradual titration (4-week intervals) significantly reduced GI discomfort compared to rapid escalation^[6].
No severe hypoglycemia or serious treatment-related adverse events reported in trials^[1]^[2].
Safety profile comparable to GLP-1 agonists when properly titrated^[12].

Complementary strategies for optimal metabolic outcomes.

Maintain a balanced, protein-forward diet with adequate micronutrients to support lean mass during weight loss.
Combine resistance training (2–3×/week) with regular aerobic activity to preserve muscle and enhance metabolic adaptations.
Prioritize sleep (7–9 hours) and stress management to support adherence and hormonal balance.
Stay well-hydrated and monitor for signs of dehydration, especially during GI side effects.
Work with healthcare providers to monitor metabolic markers (HbA1c, lipids, liver function) throughout the protocol.

Subcutaneous injection guidance from clinical best-practice resources^[13]^[14]^[15].

Clean the vial stopper and injection site with alcohol; allow to dry completely.
Pinch a skinfold; insert the needle at 45–90° into subcutaneous tissue^[13].
Do not aspirate for subcutaneous injections; inject slowly and steadily^[13].
For volumes >1.0 mL, split into 2 injections at different sites (e.g., left and right abdomen)^[5].
Rotate sites systematically (abdomen preferred; also thighs, upper arms) to avoid lipohypertrophy^[14].
Wait a few seconds after injecting before withdrawing needle to ensure full dose delivery.
Dispose of used syringes immediately in an FDA-approved sharps container^[14].

This content is intended for therapeutic educational purposes only and does not constitute medical advice, diagnosis, or treatment. Retatrutide is not FDA-approved and is available only for research purposes. All information presented is based on published clinical trial data and is not intended to encourage off-label use.

References

— Rosenstock J, et al. Retatrutide for type 2 diabetes: Phase 2 trial results (36-week study, HbA1c reductions, weight loss)

— Jastreboff AM, et al. Triple-hormone-receptor agonist Retatrutide for obesity: Phase 2 trial (48-week study, up to 24% weight loss)

— ADA Press Release: Novel agent Retatrutide results in substantial weight reduction (83rd Scientific Sessions, Phase 2 data)

— Phase 2 trial results: benefits of Retatrutide in obesity, type 2 diabetes, NASH (83rd ADA Scientific Sessions coverage)

— Study of Retatrutide (LY3437943) in adults with obesity (NCT04881760; protocol details, dosing regimens)

— Hamza M, et al. Triple agonism based therapies for obesity (review; titration strategies, GI side effect management)

— Coskun T, et al. LY3437943 (Retatrutide): discovery to clinical proof of concept (triple GLP-1/GIP/glucagon agonist, preclinical mechanism)

— Multi-receptor agonists for metabolic disease (mechanism of GLP-1/GIP/glucagon co-activation)

— Incretin-based therapies: GLP-1, GIP, and glucagon receptor pharmacology (metabolic pathways, energy expenditure)

— Jastreboff et al. obesity trial: cardiometabolic markers, liver fat reduction, lipid profiles

— Triple agonists in NAFLD/NASH: hepatic steatosis resolution (preclinical and clinical evidence)

— Rosenstock et al. diabetes trial: adverse event profiles, GI tolerability, titration schedules

— Vaccine administration: subcutaneous route (angle/site guidance; no aspiration required)

— How to give a subcutaneous injection (technique, site rotation, sharps disposal)

— Administration of medication: subcutaneous injections (aseptic technique, preparation)

— Peptide storage and handling guidelines (lyophilized and reconstituted storage conditions, stability)

— Stability of peptides during freeze-thaw cycles (best practices for aliquoting and storage)

— Retatrutide (20 mg) product page (quality specifications, batch documentation, supplier information)

Mechanism Breakdown — 3rd Party Analysis

This video provides an external overview of how Reta20 interacts with GLP-1, GIP and glucagon receptors to influence fat metabolism and energy expenditure.

External Source

Titration schedule.

Standard research titration model. Adjust under qualified clinical observation only. Not for human therapeutic use.

Phase 01

Wk 1 — 4

2 mg

Once weekly

Initiation · tolerance assessment

Phase 02

Wk 5 — 8

4 mg

Once weekly

Standard titration step

Phase 03

Wk 9 — 12

8 mg

Once weekly

Maintenance evaluation

Phase 04

Wk 13+

12 mg

Once weekly

Optional research extension

Research use only.

Reta20 is supplied strictly for in-vitro laboratory research and biochemical analysis. It is not intended for human consumption, diagnostic use, veterinary application or therapeutic administration of any kind.

Handling must be performed by qualified personnel in compliance with applicable institutional and jurisdictional safety standards. The information contained on this protocol sheet is provided for educational and reference purposes only and does not constitute medical advice.

Not for human use
Store at 2–8 °C, protected from light

Reconstitute under aseptic conditions
Document all research observations

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Reta20

Retatrutide (20 mg Vial) Dosage Protocol

Retatrutide (20 mg Vial) Dosage Protocol

Table of Contents

Quickstart Highlights

Dosing & Reconstitution Guide

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

Reconstitution Steps

Advanced / Aggressive Protocol (2 mL = ~10.0 mg/mL)

Supplies Needed

Protocol Overview

Dosing Protocol

Storage Instructions

Important Notes

How This Works

Clinical Benefits & Side Effects

Benefits

Side Effects

Lifestyle Factors

Injection Technique

Video

Important Note

References

Mechanism Breakdown — 3rd Party Analysis

Titration schedule.

Phase 01

Wk 1 — 4

2 mg

Once weekly

Initiation · tolerance assessment

Phase 02

Wk 5 — 8

4 mg

Once weekly

Standard titration step

Phase 03

Wk 9 — 12

8 mg

Once weekly

Maintenance evaluation

Phase 04

Wk 13+

12 mg

Once weekly

Optional research extension

Research use only.

Gold Tier Catalogue

Explore the full British Dragon research line.