Retatrutide

Description

Retatrutide (also known as LY3437943) is a synthetic peptide designed as a triple agonist of the GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors. It was developed to target metabolic regulation through multiple hormonal pathways, with research primarily focused on obesity and type 2 diabetes. By combining three incretin/metabolic signals in one molecule, retatrutide aims to produce stronger effects on body weight and glycemic control than single- or dual-agonist therapies.

Molecular Formula: C221H342N46O68
Molecular Weight: ~4731 g/mol
CAS Number: 2381089-83-2

What Are the Effects of Retatrutide?

Retatrutide is recognized for several key effects:

• Weight Reduction: Clinical research has shown substantial decreases in body weight in people with obesity.

• Improved Glycemic Control: Supports glucose regulation by enhancing insulin response and modulating glucagon activity depending on metabolic state.

• Appetite Suppression and Reduced Food Intake: Influences satiety pathways and eating behavior, contributing to lower caloric intake.

• Metabolic Effects (Energy/Lipid Handling): The glucagon-receptor component may influence energy expenditure and lipid metabolism, though long-term outcomes are still being studied.

How Does It Work?

Retatrutide works by simultaneously activating three receptors:

• GLP-1 receptor: increases satiety, slows gastric emptying, and improves glucose-dependent insulin secretion.

• GIP receptor: enhances insulin secretion and may improve metabolic signaling related to nutrient handling.

• Glucagon receptor: can increase energy expenditure and influence fat metabolism, but also requires careful balance because glucagon affects blood glucose.

This “three-pathway” activation is the reason retatrutide is sometimes described as a next-generation metabolic peptide compared with GLP-1–only or GLP-1/GIP dual agonists.

Scientific Evidence and Research Status

Retatrutide has been evaluated in human clinical trials, including phase 2 studies showing large reductions in body weight and improvements in metabolic markers. However, it is still considered investigational (ongoing phase 3 programs), meaning its long-term safety profile, optimal dosing strategies, and broader outcomes are still being established.

Role in Sports and Performance Contexts

In sports and physique contexts, retatrutide has drawn attention because of its strong effects on body-weight reduction and appetite suppression. That said, use outside medical research or clinical supervision raises ethical and health concerns (side effects, misuse, and unknown long-term risk).

Regarding anti-doping rules: athletes must rely on the current WADA Prohibited List (updated yearly). Retatrutide may not always be named explicitly in public summaries, so competitive athletes should verify status through official anti-doping resources and medical staff.

Standard Dosage

Escalate every 4 weeks: 2 mg (weeks 5-8), 4 mg (weeks 9-12), 8 mg (weeks 13-16), reaching 12 mg maintenance from week 17+. Consistent weekly timing optimizes steady-state levels.

Concentration Breakdown

Reconstituting 5 mg (5000 mcg) of retatrutide in 2 mL yields a concentration of:

5000 mcg ÷ 2 mL = 2500 mcg/mL

Weekly Protocol (4 Weeks)

Clinical trials have included once-weekly dosing arms such as 1 mg (among others).
For a 1 mg (1000 mcg) dose:

• Volume: 1000 mcg ÷ 2500 mcg/mL = 0.4 mL

• In a 50-unit syringe: 0.4 mL = 40 units

Doses per vial: 5000 mcg ÷ 1000 mcg = 5 doses per vial
4-week cycle needs: 4 doses total → 1 vial suffices

Higher Weekly Protocol (4 Weeks)

Trials have also studied higher weekly doses such as 4 mg (and above).
For a 4 mg (4000 mcg) dose:

• Volume: 4000 mcg ÷ 2500 mcg/mL = 1.6 mL

• In a 50-unit syringe: 1.6 mL = 160 units (requires multiple syringe fills)

Doses per vial: 5000 mcg ÷ 4000 mcg = 1.25 doses per vial
4-week cycle needs: 4 doses total = 16 mg → about 4 vials required

Given the variability of investigational dosing, the absence of standardized non-research guidelines, and the need for medical monitoring, professional medical advice is essential for safety.

Storage Instructions