RTZ-GLP3
Also known as: Retatrutide, LY3437943
Quick summary
An investigational single peptide that activates three hormone receptors at once: GIP, GLP-1 and glucagon. Research focus: triple incretin/glucagon agonism, body-weight regulation and glucose metabolism. This page leads with SRP's low-and-slow starting dose.
Overview
An investigational single peptide that activates three hormone receptors at once: GIP, GLP-1 and glucagon. It is studied in clinical trials on body weight and metabolism.
Looking for research material? Simple Research Peptides lists RTZ-GLP3 (12 mg Vial) for laboratory research use.
Mechanism
Retatrutide activates the GIP, GLP-1 and glucagon receptors. Adding the glucagon receptor is thought to raise energy expenditure and fat use in the liver, on top of the incretin effects.
Research areas
- triple incretin/glucagon agonism
- body-weight regulation
- glucose metabolism
Storage & reconstitution
Typically supplied as a lyophilized powder; keep sealed vials cold (refrigerated short term, frozen for long-term holding) and away from light. Laboratories commonly reconstitute with bacteriostatic or sterile water, swirling gently rather than shaking, and keep the solution refrigerated, using it within a few weeks.
Recommended starting dose (low and slow)
| Starting dose | Phase 2 trial schedule: 2 mg once weekly, subcutaneous. Trial doses only; retatrutide is not approved. |
|---|---|
| Frequency | Once weekly, subcutaneous. |
| Reconstitution | Examples: 10 mg vial + 2 mL bacteriostatic water = 5 mg/mL; 10 mg vial + 1 mL water = 10 mg/mL; 10mg vial + 2mL diluent (as listed). Different water volumes can be used; that only changes the draw volume, not the amount of peptide. storage note: Reconstituted: refrigerate; used within 4–8 weeks. |
Studied higher doses
Studies have used doses up to the amounts below. Higher doses can be dangerous. Whether a person can reach them safely depends on height, weight, activity level, training and pre-existing conditions. We recommend following the lower starting dose above, and contacting SRP with any questions.
| Highest amount reported in studies | Highest dose in the trial schedule: 12 mg once weekly. |
|---|---|
| Step-up schedules reported | Phase 2 trial schedule: increase by 2 mg every 4 weeks, reaching 12 mg after about 20 weeks. |
Route and timing
Route: Subcutaneous injection after reconstitution is the route most often described in research protocols.
Timing: Pending - to be added by SRP
Cycle length and repeat
Pending - to be added by SRP
Half-life
Approximate, for Bobby's review: About 6 days.
Side effects
Pending - to be added by SRP
Suggested bloodwork and monitoring
Draft, for Bobby's review: CBC and comprehensive metabolic panel (kidney and liver function, electrolytes) before starting and again after a few weeks; fasting glucose, HbA1c and lipid panel; lipase where GLP-1 or amylin-pathway compounds are involved.
Cautions
Pending - to be added by SRP
Reconstitution calculator
Math aid only. It converts the numbers you enter; it is not dosing advice. For research use only. Prefilled with this page's vial size, reconstitution and low-and-slow starting dose where known; change any value.
Frequently asked questions
What is RTZ-GLP3 studied for?
In research it is studied for triple incretin/glucagon agonism, body-weight regulation and glucose metabolism. Retatrutide activates the GIP, GLP-1 and glucagon receptors.
How is RTZ-GLP3 given in research?
Subcutaneous injection after reconstitution is the route most often described in research protocols. See the dosing frequency block on this page for how often.
What amount should a researcher start with?
This page lists SRP's low-and-slow starting dose in the Recommended starting dose section. Higher amounts that appear in studies are listed separately with their safety context. Start with the lower dose and contact SRP with any questions.
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Last updated: October 19, 2026