Updated April 2026

Retatrutide Dosing Protocol

Founder & Lead Researcher · B.S. Civil Engineering, UCLA

Last updated: April 2026

Complete Retatrutide dosing protocol and safety guide covering the retatrutide titration schedule, retatrutide reconstitution, retatrutide side effects, and clinical trial outcomes. Retatrutide is a once-weekly investigational triple agonist frequently compared with Cagrilintide, and readers exploring that pairing can also review the Cagrilintide + Retatrutide stack protocol. This page is built to help you understand what the dose ranges, tables, and trial results actually mean before you dig into the details.

Half-life

~6 days

Dose range

1 mg to 12 mg weekly

Status

Phase 3 investigational

Developer

Eli Lilly and Company

Need to calculate reconstitution and dosing units? Use the peptide reconstitution calculator.

Quick Reference Dosing Card

Peptide Name

Retatrutide (LY3437943)

Use Case

Research readers usually look at retatrutide for weight-loss and metabolic research because it affects appetite, blood-sugar signaling, and calorie burn at the same time.

Category / Class

Metabolic triple agonist. That means retatrutide acts on GLP-1, GIP, and glucagon receptors rather than just one pathway.

Half-Life

~6 days

Dosing Frequency

Once weekly (subcutaneous injection)

Dose Range

1 mg - 12 mg per week

Titration Schedule

1 mg -> 2 mg -> 4 mg -> 6 mg -> 9 mg -> 12 mg, typically increased every 4 weeks

Common Vial Sizes

5 mg, 10 mg, 20 mg, 30 mg

Route of Administration

Subcutaneous (SubQ)

Regulatory Status

Retatrutide is still investigational. Lilly says it has not been approved by any regulatory agency as of March 2026, and it remains in Phase 3 clinical trials.

Developer

Eli Lilly and Company

Key Stat

In clinical trials, higher-dose retatrutide produced strong weight-loss results: up to 24.2% at 48 weeks in Phase 2 and up to 28.7% at 68 weeks in Phase 3 TRIUMPH-4.

Peptide Name	Retatrutide (LY3437943)
Use Case	Research readers usually look at retatrutide for weight-loss and metabolic research because it affects appetite, blood-sugar signaling, and calorie burn at the same time.
Category / Class	Metabolic triple agonist. That means retatrutide acts on GLP-1, GIP, and glucagon receptors rather than just one pathway.
Half-Life	~6 days
Dosing Frequency	Once weekly (subcutaneous injection)
Dose Range	1 mg - 12 mg per week
Titration Schedule	1 mg -> 2 mg -> 4 mg -> 6 mg -> 9 mg -> 12 mg, typically increased every 4 weeks
Common Vial Sizes	5 mg, 10 mg, 20 mg, 30 mg
Route of Administration	Subcutaneous (SubQ)
Regulatory Status	Retatrutide is still investigational. Lilly says it has not been approved by any regulatory agency as of March 2026, and it remains in Phase 3 clinical trials.
Developer	Eli Lilly and Company
Key Stat	In clinical trials, higher-dose retatrutide produced strong weight-loss results: up to 24.2% at 48 weeks in Phase 2 and up to 28.7% at 68 weeks in Phase 3 TRIUMPH-4.

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What Is Retatrutide?

Retatrutide (LY3437943) is an investigational once-weekly peptide from Eli Lilly being studied for obesity and related metabolic conditions. What makes retatrutide different is that it works on three hormone pathways at once: GLP-1, GIP, and glucagon.

Geometric diagram illustrating Retatrutide as a triple-agonist peptide concept, showing three flowing streams (Blue, Green, Red) simultaneously activating GLP-1, GIP, and Glucagon (GCGR) receptor icons on a pristine white background with minimal labels.

For most readers, that matters because those three pathways are linked to appetite, blood-sugar control, and energy expenditure. In plain terms, retatrutide is being studied as a broader metabolic therapy than semaglutide (GLP-1 only) or tirzepatide (GLP-1 + GIP).

Structurally, retatrutide is a 39-amino acid single-chain peptide with a C20 fatty diacid attachment that helps it bind to albumin in the bloodstream. That longer circulation time is why retatrutide half-life is about 6 days and why the protocol uses once-weekly dosing.

Retatrutide is currently being studied across Eli Lilly's Phase 3 TRIUMPH and TRANSCEND programs in obesity, type 2 diabetes, knee osteoarthritis pain, obstructive sleep apnea, chronic low back pain, cardiovascular and renal outcomes, and metabolic dysfunction-associated steatotic liver disease (MASLD). Lilly released TRIUMPH-4 topline osteoarthritis results on December 11, 2025 and announced first Phase 3 type 2 diabetes topline results from TRANSCEND-T2D-1 on March 19, 2026. Lilly says additional results from the retatrutide clinical trial program are expected over the next year.

Retatrutide is not FDA-approved and is currently available only through clinical trials. All information on this page is for educational and research reference purposes only.

How Retatrutide Works: Triple Receptor Agonism

Retatrutide works through three receptor pathways at the same time. The simplest way to think about it is this: one pathway helps you feel full, one improves how the body handles glucose and stored fuel, and one may increase energy expenditure.

3-Panel Pathway Infographic

A minimalist, three-panel infographic triptych illustrating the three biological pathways: Left panel (Blue GLP-1) for 'SATIETY'; Central panel (Green GIP) for 'INSULIN'; and Right panel (Red Glucagon) for 'METABOLISM' using glowing line-art icons and minimal bold text callouts on a clean white surface with natural soft light.

GLP-1 Receptor (Glucagon-Like Peptide-1)

This pathway slows digestion and helps you feel full longer, which is one reason retatrutide can reduce appetite. It is the same general pathway used by semaglutide, so readers coming from GLP-1 research will recognize this part of the mechanism.

GIP Receptor (Glucose-Dependent Insulinotropic Polypeptide)

This pathway appears to help with insulin response and how the body handles fat and energy. You do not need to remember the receptor biology to use the page: the practical takeaway is that GIP is part of why retatrutide is studied as a broader metabolic compound rather than a single-pathway appetite suppressant.

Glucagon Receptor (GCGR)

This is the extra pathway that separates retatrutide from tirzepatide. It may help explain the stronger liver-fat and weight-loss data because glucagon receptor activity is linked to higher energy expenditure and fat oxidation.

Retatrutide's engineered potency ratio matters mainly because one peptide is affecting appetite, glucose handling, and calorie burn at the same time. Think of it as a three-lever system rather than a single on-off switch.

Tools for this Protocol

dose to units converter for reconstitution and units.
calculate injection units to lock in syringe draw volume.

Retatrutide Dosing Protocol & Titration Schedule

Use this retatrutide dosing protocol as a slow escalation plan, not a dose you jump into. The retatrutide starting dose in clinical trials is 1 mg once weekly, and the retatrutide titration schedule climbs over time so tolerance can build before higher doses are reached.

Phase 1 - Initiation

Weeks 1-4

1 mg once weekly

Starting dose to assess initial tolerance. Minimal metabolic effects expected at this dose.

Phase 2 - Early Escalation

Weeks 5-8

2 mg once weekly

First meaningful dose increase. GI side effects (nausea) may begin.

Phase 3 - Mid Escalation

Weeks 9-12

4 mg once weekly

Appetite suppression typically becomes noticeable. Weight loss begins accelerating.

Phase 4 - High Escalation

Weeks 13-16

6 mg once weekly

TRIUMPH Phase 3 added this intermediate step (not present in Phase 2 trials).

Phase 5 - Therapeutic Range

Weeks 17-20

9 mg once weekly

Phase 3 target dose. Significant weight loss expected.

Phase 6 - Maximum Studied Dose

Weeks 21+

12 mg once weekly

Maximum dose studied in clinical trials. 24.2% average weight loss at 48 weeks (Phase 2). 28.7% at 68 weeks (Phase 3, TRIUMPH-4).

Phase	Weeks	Weekly Dose	Notes
Phase 1 - Initiation	Weeks 1-4	1 mg once weekly	Starting dose to assess initial tolerance. Minimal metabolic effects expected at this dose.
Phase 2 - Early Escalation	Weeks 5-8	2 mg once weekly	First meaningful dose increase. GI side effects (nausea) may begin.
Phase 3 - Mid Escalation	Weeks 9-12	4 mg once weekly	Appetite suppression typically becomes noticeable. Weight loss begins accelerating.
Phase 4 - High Escalation	Weeks 13-16	6 mg once weekly	TRIUMPH Phase 3 added this intermediate step (not present in Phase 2 trials).
Phase 5 - Therapeutic Range	Weeks 17-20	9 mg once weekly	Phase 3 target dose. Significant weight loss expected.
Phase 6 - Maximum Studied Dose	Weeks 21+	12 mg once weekly	Maximum dose studied in clinical trials. 24.2% average weight loss at 48 weeks (Phase 2). 28.7% at 68 weeks (Phase 3, TRIUMPH-4).

Important Titration Notes

Titration pacing matters. In the Phase 2 NEJM trial (2023), GI side effect rates nearly doubled when participants were assigned directly to 8 mg instead of gradually titrating from 1-2 mg.

Dose flexibility: Trial protocols allowed participants to stay at the current dose for an extra 2-4 weeks when nausea or other GI side effects were significant.

Phase 3 dose levels: TRIUMPH evaluates 4 mg, 9 mg, and 12 mg as target maintenance doses.

Missed dose guidance: If a scheduled dose is missed, it can be taken within 5 days. If more than 5 days have passed, skip it and resume on the next scheduled injection day.

Retatrutide Reconstitution Guide

This retatrutide reconstitution guide answers two separate questions: how much bacteriostatic water to add to the vial, and how many syringe units match your target dose after mixing. If you are wondering how to reconstitute retatrutide, read across your vial-size row first, then match the final concentration to your dose.

Vial Size: 5 mg

BAC Water: 1.0 mL

Concentration: 5,000 mcg/mL (5.0 mg/mL)

1 mg: 0.20 mL (20 units)

2 mg: 0.40 mL (40 units)

4 mg: 0.80 mL (80 units)

8 mg: N/A - exceeds vial

12 mg: N/A

Vial Size: 10 mg

BAC Water: 2.0 mL

Concentration: 5,000 mcg/mL (5.0 mg/mL)

1 mg: 0.20 mL (20 units)

2 mg: 0.40 mL (40 units)

4 mg: 0.80 mL (80 units)

8 mg: Requires 2 vials

12 mg: Requires 2-3 vials

Vial Size: 20 mg

BAC Water: 2.0 mL

Concentration: 10,000 mcg/mL (10.0 mg/mL)

1 mg: 0.10 mL (10 units)

2 mg: 0.20 mL (20 units)

4 mg: 0.40 mL (40 units)

8 mg: 0.80 mL (80 units)

12 mg: 1.20 mL - split draw

Vial Size: 30 mg

BAC Water: 3.0 mL

Concentration: 10,000 mcg/mL (10.0 mg/mL)

1 mg: 0.10 mL (10 units)

2 mg: 0.20 mL (20 units)

4 mg: 0.40 mL (40 units)

8 mg: 0.80 mL (80 units)

12 mg: 1.20 mL - split draw

Vial Size	BAC Water Added	Concentration	1 mg Dose	2 mg Dose	4 mg Dose	8 mg Dose	12 mg Dose
5 mg	1.0 mL	5,000 mcg/mL (5.0 mg/mL)	0.20 mL (20 units)	0.40 mL (40 units)	0.80 mL (80 units)	N/A - exceeds vial	N/A
10 mg	2.0 mL	5,000 mcg/mL (5.0 mg/mL)	0.20 mL (20 units)	0.40 mL (40 units)	0.80 mL (80 units)	Requires 2 vials	Requires 2-3 vials
20 mg	2.0 mL	10,000 mcg/mL (10.0 mg/mL)	0.10 mL (10 units)	0.20 mL (20 units)	0.40 mL (40 units)	0.80 mL (80 units)	1.20 mL - split draw
30 mg	3.0 mL	10,000 mcg/mL (10.0 mg/mL)	0.10 mL (10 units)	0.20 mL (20 units)	0.40 mL (40 units)	0.80 mL (80 units)	1.20 mL - split draw

Reconstitution Step-by-Step

Minimalist photographic close-up sequence illustrating reconstitution guide: STEP 1: VIAL (Retatrutide 10mg RUO); STEP 2: DRAW (Opened BAC Water & Syringe); STEP 3: MIX (Syringe infusing into Retatrutide vial). Minimal glowing callout lines link to receptor pathways, with Blue and Red highlights emphasizing the process on clean glass and metal.

Let the lyophilized retatrutide vial and bacteriostatic water come to room temperature.
Clean both vial tops with alcohol and let them dry.
Draw the calculated amount of bacteriostatic water with a sterile syringe.
Inject the water slowly down the inside wall of the vial instead of spraying the powder directly.
Gently swirl until the solution is clear. Do not shake.
Label the vial with the retatrutide concentration and reconstitution date.
Refrigerate at 2-8C (35.6-46.4F) and use within 2-4 weeks.

Need exact syringe units for a custom vial size or BAC water volume? Use the free peptide reconstitution calculator.Open Calculator

Retatrutide Side Effects - What Clinical Trials Show

Retatrutide side effects look broadly similar to other incretin-based therapies, but the easiest way to understand them is in two buckets: stomach-related symptoms during dose escalation and a separate skin-sensation signal at higher doses.

Common gastrointestinal effects: In Phase 2 (NEJM), nausea occurred in up to 25% of participants at 12 mg, diarrhea up to 23%, vomiting up to 26%, and constipation up to 16%. These issues were most common during escalation and were usually mild to moderate.

Cardiovascular signal: Resting heart rate increased by about 5-10 bpm on average, peaking near week 24 and easing by weeks 36-48. No increase in serious cardiovascular events was reported.

Dysesthesia in Phase 3: TRIUMPH-4 on December 11, 2025 reported dysesthesia, meaning unusual skin sensitivity or tingling, in about 20.9% at the highest dose.

Liver enzymes: Temporary ALT/AST elevations occurred in a minority of participants and were generally linked to dose increases.

Injection site reactions: Redness, itching, and small nodules were observed in roughly 5-15% of participants.

Discontinuation: In Phase 2, 6-16% stopped because of adverse events versus 0% on placebo. Slow titration improved adherence.

Retatrutide Clinical Trial Results

Retatrutide clinical trial results are strongest in obesity studies, with additional signals in type 2 diabetes, liver-fat reduction, and osteoarthritis-related pain. The simplest way to read the table is that higher-dose retatrutide has produced unusually large weight-loss effects for an investigational once-weekly peptide, but the program is still ongoing and not yet FDA-approved.

Jastreboff et al., NEJM 2023

Phase 2 • 48 weeks

338 adults with obesity (no diabetes)

12 mg: -24.2% body weight; 8 mg: -22.8%; 4 mg: -17.5%. 100% of 8 mg and 12 mg participants lost >=5%.

TRIUMPH-4, Eli Lilly 2025

Phase 3 • 68 weeks

Adults with obesity + knee osteoarthritis

12 mg: -28.7% body weight; 9 mg: similar results. Also significant pain reduction (WOMAC -4.5 points).

Rosenstock et al., Lancet 2023

Phase 2 • 36 weeks

Adults with type 2 diabetes

Up to -16.9% weight loss. HbA1c improved by -2.2%. 82% reached HbA1c <=6.5%.

Sanyal et al., Nature Medicine 2024

Phase 2 substudy • 48 weeks

Adults with MASLD and >=10% liver fat

Up to 82% relative reduction in liver fat at 24 weeks.

Trial	Phase	Duration	Population	Key Result
Jastreboff et al., NEJM 2023	Phase 2	48 weeks	338 adults with obesity (no diabetes)	12 mg: -24.2% body weight; 8 mg: -22.8%; 4 mg: -17.5%. 100% of 8 mg and 12 mg participants lost >=5%.
TRIUMPH-4, Eli Lilly 2025	Phase 3	68 weeks	Adults with obesity + knee osteoarthritis	12 mg: -28.7% body weight; 9 mg: similar results. Also significant pain reduction (WOMAC -4.5 points).
Rosenstock et al., Lancet 2023	Phase 2	36 weeks	Adults with type 2 diabetes	Up to -16.9% weight loss. HbA1c improved by -2.2%. 82% reached HbA1c <=6.5%.
Sanyal et al., Nature Medicine 2024	Phase 2 substudy	48 weeks	Adults with MASLD and >=10% liver fat	Up to 82% relative reduction in liver fat at 24 weeks.

Minimalist line graph illustrating Average % Body Weight Loss Over Time for Retatrutide. X-axis 'WEEKS 0, 36, 68' and Y-axis '0%, -15%, -25%, -30%'. Three data lines: Top (Grey PLACEBO); Middle (Green RETATRUTIDE 9mg); Bottom (Blue RETATRUTIDE 12mg) with glowing effects and simple bold labels on pristine white with minimal text.

As of April 5, 2026, Lilly's retatrutide Phase 3 work spans the TRIUMPH obesity program and the TRANSCEND-T2D diabetes program, with additional studies in obstructive sleep apnea, chronic low back pain, cardiovascular and renal outcomes, and MASLD. TRIUMPH-4 topline osteoarthritis results were released on December 11, 2025, and Lilly announced positive TRANSCEND-T2D-1 topline results on March 19, 2026. Lilly says additional results from the retatrutide clinical trial program are expected over the next year, but retatrutide remains investigational and not approved by any regulatory agency.

Storage & Handling

Use the storage table as a priority guide. For most readers, the main rule is simple: keep reconstituted retatrutide refrigerated at 2-8C, protect it from light, and plan to use it within 2-4 weeks.

Lyophilized powder is more temperature-tolerant than mixed solution, which is why short shipping exposure is usually less concerning than poor storage after reconstitution.

Lyophilized (powder, sealed)

-20C (-4F) or below (freezer)

Long-term - up to 12+ months

Lyophilized (powder, sealed)

2-8C (35.6-46.4F) (refrigerator)

Several months

Lyophilized (powder, sealed)

Room temperature (during shipping)

Stable for several weeks - peptide powders tolerate short-term temperature fluctuations

Reconstituted (solution)

2-8C (35.6-46.4F) (refrigerator)

Use within 2-4 weeks

Reconstituted (solution)

-20C (-4F) (frozen aliquots)

3-4 months

State	Temperature	Duration
Lyophilized (powder, sealed)	-20C (-4F) or below (freezer)	Long-term - up to 12+ months
Lyophilized (powder, sealed)	2-8C (35.6-46.4F) (refrigerator)	Several months
Lyophilized (powder, sealed)	Room temperature (during shipping)	Stable for several weeks - peptide powders tolerate short-term temperature fluctuations
Reconstituted (solution)	2-8C (35.6-46.4F) (refrigerator)	Use within 2-4 weeks
Reconstituted (solution)	-20C (-4F) (frozen aliquots)	3-4 months

Avoid repeated freeze-thaw cycles, and if long-term storage is necessary, freeze single-use aliquots rather than the same vial over and over. Bacteriostatic water (0.9% benzyl alcohol) is preferred for multi-dose workflows.

Retatrutide vs. Tirzepatide vs. Semaglutide

Retatrutide vs tirzepatide vs semaglutide is mainly a question of how many metabolic pathways each compound activates. Semaglutide is single-pathway, tirzepatide is dual-pathway, and retatrutide is triple-pathway, which may help explain why retatrutide has shown stronger weight-loss and liver-fat results in trials.

Receptor Targets

Retatrutide: GLP-1 + GIP + Glucagon (triple)

Tirzepatide: GLP-1 + GIP (dual)

Semaglutide: GLP-1 only (single)

Half-Life

Retatrutide: ~6 days

Tirzepatide: ~5 days

Semaglutide: ~7 days

Dosing Frequency

Retatrutide: Once weekly

Tirzepatide: Once weekly

Semaglutide: Once weekly

Max Studied Dose

Retatrutide: 12 mg/week

Tirzepatide: 15 mg/week

Semaglutide: 2.4 mg/week

Peak Weight Loss (Trials)

Retatrutide: -28.7% at 68 weeks (Phase 3)

Tirzepatide: -22.5% at 72 weeks (SURMOUNT-1)

Semaglutide: -15.8% at 68 weeks (STEP-1)

FDA Status (Apr 2026)

Retatrutide: Investigational - Phase 3

Tirzepatide: Approved (obesity + T2D)

Semaglutide: Approved (obesity + T2D)

Liver Fat Reduction

Retatrutide: Up to 82% reduction (substudy)

Tirzepatide: Significant reduction

Semaglutide: Moderate reduction

Unique Advantage

Retatrutide: Triple agonism increases energy expenditure via glucagon

Tirzepatide: Dual agonism balances efficacy and tolerability

Semaglutide: Longest clinical track record, CV outcomes data (SELECT trial)

Feature	Retatrutide	Tirzepatide	Semaglutide
Receptor Targets	GLP-1 + GIP + Glucagon (triple)	GLP-1 + GIP (dual)	GLP-1 only (single)
Half-Life	~6 days	~5 days	~7 days
Dosing Frequency	Once weekly	Once weekly	Once weekly
Max Studied Dose	12 mg/week	15 mg/week	2.4 mg/week
Peak Weight Loss (Trials)	-28.7% at 68 weeks (Phase 3)	-22.5% at 72 weeks (SURMOUNT-1)	-15.8% at 68 weeks (STEP-1)
FDA Status (Apr 2026)	Investigational - Phase 3	Approved (obesity + T2D)	Approved (obesity + T2D)
Liver Fat Reduction	Up to 82% reduction (substudy)	Significant reduction	Moderate reduction
Unique Advantage	Triple agonism increases energy expenditure via glucagon	Dual agonism balances efficacy and tolerability	Longest clinical track record, CV outcomes data (SELECT trial)

That extra glucagon activity is also one reason retatrutide is harder to compare on tolerability alone. The same pathway that may increase energy expenditure may also help explain the dysesthesia signal seen in Phase 3.

These compounds are not interchangeable. Reconstitution math, dose ranges, approval status, and evidence maturity differ for each one.

See the tirzepatide protocol and semaglutide protocol for compound-specific guides.

Retatrutide Stacking Protocols

Before combining compounds, read the full stacking safety guide on PepPal.

Stack: Metabolic Research Stack

Retatrutide + MOTS-c

Dual-pathway metabolic modulation targeting GLP-1/GIP/glucagon signaling (retatrutide) and mitochondrial signaling (MOTS-c) in preclinical research models.

MOTS-c is a mitochondria-derived peptide studied for exercise-mimetic effects and metabolic regulation. Combined with retatrutide, this stack represents a complementary multi-pathway research approach.

See the compound-specific MOTS-c protocol for additional context.

View full Metabolic Research Stack protocol

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Frequently Asked Questions - Retatrutide

Q1: What is the starting dose of retatrutide?

The starting dose of retatrutide in clinical trials is 1 mg once weekly for the first 4 weeks. That low starting point gives the body time to adjust before the retatrutide titration schedule moves higher.

Q2: What is retatrutide's half-life?

Retatrutide half-life is about 6 days, which is why the dosing schedule is usually once weekly. The technical reason is albumin binding, but the practical takeaway is simply that retatrutide stays active long enough to support weekly dosing.

Q3: How much weight can you lose on retatrutide?

In the Phase 2 trial (NEJM, 2023), participants on 12 mg lost an average of 24.2% body weight at 48 weeks. Lilly released Phase 3 TRIUMPH-4 topline results on December 11, 2025 showing weight loss up to 28.7% at 68 weeks. Results were dose-dependent.

Q4: How do you reconstitute retatrutide?

To reconstitute retatrutide, add bacteriostatic water based on the vial size and the concentration you want, then use the table to match your dose to syringe units. For example, a 10 mg vial mixed with 2.0 mL gives 5,000 mcg/mL. Inject the water down the vial wall, swirl gently, do not shake, refrigerate at 2-8C, and use within 2-4 weeks.

Q5: Is retatrutide FDA-approved?

No. As of April 5, 2026, retatrutide is not FDA-approved. Lilly says it has not been approved by any regulatory agency and remains investigational in ongoing Phase 3 trials.

Q6: What are the most common side effects of retatrutide?

The most common retatrutide side effects are stomach-related: nausea, diarrhea, vomiting, and constipation, especially during dose escalation. At the highest dose in Phase 3, some participants also reported dysesthesia, which means unusual skin sensitivity or tingling.

Q7: How does retatrutide compare to tirzepatide and semaglutide?

Retatrutide is a triple agonist, tirzepatide is a dual agonist, and semaglutide is a single agonist. In plain terms, retatrutide acts on more pathways at once, which may help explain the stronger weight-loss results seen so far, but retatrutide is still investigational while tirzepatide and semaglutide are FDA-approved.

Q8: What vial sizes does retatrutide come in?

Research-grade retatrutide is commonly available in 5 mg, 10 mg, 20 mg, and 30 mg vial sizes. Vial size affects reconstitution math and doses per vial.

Q9: How much bacteriostatic water should I add to a retatrutide vial?

It depends on vial size and target concentration. Common mixes: 5 mg + 1.0 mL = 5,000 mcg/mL; 10 mg + 2.0 mL = 5,000 mcg/mL; 20 mg + 2.0 mL = 10,000 mcg/mL; 30 mg + 3.0 mL = 10,000 mcg/mL. Calculator: https://www.peppal.app/calculator

Q10: What is the maximum dose of retatrutide studied in clinical trials?

The maximum weekly dose studied is 12 mg. In Phase 2, 12 mg reached -24.2% at 48 weeks, and in Phase 3 TRIUMPH-4 up to -28.7% at 68 weeks.

Q11: How should reconstituted retatrutide be stored?

Store reconstituted retatrutide at 2-8C, protected from light, and use within 2-4 weeks. Lyophilized powder is generally stored at -20C for long-term stability. Avoid repeated freeze-thaw cycles.

Q12: What is the TRIUMPH clinical trial program?

TRIUMPH is Eli Lilly's Phase 3 obesity-focused retatrutide program. It includes obesity or overweight studies plus work in knee osteoarthritis pain, obstructive sleep apnea, chronic low back pain, cardiovascular and renal outcomes, and MASLD. Lilly's separate TRANSCEND-T2D Phase 3 program covers type 2 diabetes.

Q13: Where can I calculate reconstitution and syringe units?

Use the PepPal calculator for exact dose-to-unit conversions.

Q14: Where can I compare peptide suppliers?

Browse the PepPal supplier directory for current supplier listings.

Sources & Research

Jastreboff AM, Kaplan LM, Frias JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. New England Journal of Medicine, 2023 DOI: 10.1056/NEJMoa2301972.
Rosenstock J, Frias JP, Jastreboff AM, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. The Lancet, 2023 DOI: 10.1016/S0140-6736(23)01053-X.
Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nature Medicine, 2024 DOI: 10.1038/s41591-024-03018-2.
Eli Lilly and Company. Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial. Press Release, December 11, 2025 Link.
Eli Lilly and Company. Lilly's triple agonist, retatrutide, demonstrated significant reductions in A1C and weight in first Phase 3 trial for treatment of type 2 diabetes. Press Release, March 19, 2026 Link.
Karras SN, Koufakis T, Papakonstantinou E, et al. Retatrutide-A Game Changer in Obesity Pharmacotherapy. Metabolites, 2025 PMC Article.
Ali F, et al. Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist for obesity treatment: a systematic review and meta-analysis of randomized controlled trials. Baylor University Medical Center Proceedings, 2025 PMC Article.
Sattar N, et al. Effects of once-weekly subcutaneous retatrutide on weight and metabolic markers: A systematic review and meta-analysis of randomized controlled trials. Obesity Reviews, 2024 PMC Article.
Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. Cell Metabolism, 2022 DOI: 10.1016/j.cmet.2022.07.013.
ClinicalTrials.gov — (NCT05929066), (NCT05931367), (NCT07035093), (NCT07232719).
Wikipedia - Retatrutide. Link.

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Disclaimer: The information on this page is for educational and research reference purposes only. Retatrutide is an investigational compound not approved by the FDA. No compounds discussed on this site are intended for human consumption. This is not medical advice. Consult a qualified healthcare professional before considering any peptide protocol. Protocol data is compiled from published clinical trials, peer-reviewed literature, and community research documentation.

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