GLP-3 is an informal term for the next generation of metabolic peptides, specifically triple agonists that activate the GLP-1, GIP, and glucagon receptors simultaneously. The compound most associated with this term is retatrutide (LY3437943). The name stuck because it follows the GLP-1 to dual agonist to triple agonist progression.

Is retatrutide FDA approved?

No. As of 2024, retatrutide is an investigational compound in clinical trials. It is not approved for any medical use and is not available as a prescription drug. It is available as a research chemical for in vitro and preclinical laboratory use only.

How does retatrutide compare to semaglutide?

Semaglutide is a GLP-1 receptor agonist only. Retatrutide activates GLP-1R, GIPR, and GCGR — three receptors versus one. Phase 3 retatrutide data shows approximately 30% body weight loss over 80 weeks, compared to about 14.9% for semaglutide (Wegovy) in its Phase 3 program. GLP-1 suppresses appetite, GIP enhances insulin response, and glucagon receptor activation increases energy expenditure.

What is retatrutide's half-life?

Approximately 6 days, or roughly 144 hours. This enables once-weekly subcutaneous dosing. Steady-state plasma concentrations are typically reached after 4 to 5 weeks of weekly dosing.

How do you reconstitute retatrutide for research?

Retatrutide is typically supplied as a lyophilized powder in a sealed vial. Researchers add bacteriostatic water (BAC water) using a sterile syringe, injecting slowly against the side of the vial to avoid shaking the peptide. The resulting concentration depends on the ratio of powder (mg) to liquid (mL). Use the reconstitution calculator at glp-3.us/reconstitution-calculator to get exact volumes.

What receptors does retatrutide target?

Three receptors: the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon receptor (GCGR). This triple agonism is what distinguishes it from semaglutide (GLP-1R only) and tirzepatide (GLP-1R + GIPR).

How much weight loss does retatrutide cause?

Phase 3 data shows an average of approximately 30% body weight loss (about 70 lbs) over 80 weeks, with more than 45% of participants losing over 30% of body weight. The Phase 2 trial published in NEJM in 2023 showed up to 17.5% mean body weight reduction at 24 weeks in the highest-dose arm. The Phase 3 numbers are on par with weight-loss surgery outcomes.

What is the difference between GLP-1, GLP-2, and GLP-3?

GLP-1 and GLP-2 are real hormones produced from the proglucagon gene. GLP-1 has well-characterized metabolic effects; GLP-2 is primarily involved in intestinal health. The term GLP-3 in the research peptide space refers informally to triple agonist compounds like retatrutide, not the actual GLP-3 peptide produced from proglucagon.

Is retatrutide the same as tirzepatide?

No. Tirzepatide (Mounjaro/Zepbound) is a dual agonist targeting GLP-1R and GIPR. Its best Phase 3 result is approximately 22.5% body weight loss over 72 weeks. Retatrutide adds glucagon receptor agonism, making it a triple agonist, and Phase 3 data shows approximately 30% body weight loss over 80 weeks. They are separate compounds at different development stages.

Where can I find the clinical trial data for retatrutide?

The primary Phase 2 data is published in the New England Journal of Medicine: Jastreboff AM et al., Triple Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial, NEJM 2023. Additional analyses appear on PubMed and ClinicalTrials.gov under NCT04881760.

GLP-3.us — GLP 3 Peptide Retatrutide Research

Home: GLP 3 Retatrutide Research Guide
What Is GLP-3 Retatrutide?
GLP-1 vs GLP-3
How Retatrutide Works
Retatrutide Results: Weight Loss Data
Retatrutide Brand Name
Retatrutide FDA Approval Timeline
Retatrutide Availability
Phase 3 TRIUMPH Trials
Retatrutide vs Tirzepatide
Retatrutide vs Semaglutide
Retatrutide vs Ozempic
Retatrutide vs Wegovy
Retatrutide vs Zepbound
Retatrutide Side Effects
Retatrutide and Nausea
Retatrutide and Heart Rate
Retatrutide and Hair Loss
Retatrutide and Muscle Loss
Retatrutide for Women
Retatrutide for Type 2 Diabetes
Retatrutide for Fatty Liver
Retatrutide and Alcohol
Retatrutide Half-Life
Dosing Protocol
Retatrutide Microdosing
Switching to Retatrutide
Dosing Timeline: Week by Week
Retatrutide Cost Guide
Where to Buy GLP 3
Reconstitution Calculator
Cost Calculator
Dosing Planner