What is Retatrutide? The Complete Guide to the Triple GLP-1/GIP/Glucagon Agonist (2025)

Retatrutide is generating more excitement in the research and medical community than any other compound in recent memory. As a triple receptor agonist targeting GLP-1, GIP and glucagon pathways simultaneously, it represents a significant step beyond existing single and dual agonists like Ozempic and Mounjaro.

In this complete guide we cover everything you need to know about Retatrutide — how it works, what clinical trials have shown, available doses, potential side effects and where to buy pharmaceutical grade Retatrutide online.

What is Retatrutide?

Retatrutide (also known as LY3437943) is a novel triple receptor agonist developed by Eli Lilly. Unlike existing GLP-1 medications which target one or two receptors, Retatrutide simultaneously activates three distinct hormone receptors:

• GLP-1 (Glucagon-Like Peptide-1) — regulates appetite, slows gastric emptying and stimulates insulin secretion
• GIP (Glucose-Dependent Insulinotropic Polypeptide) — enhances insulin release and supports fat metabolism
• Glucagon receptor — increases energy expenditure and promotes fat burning in the liver

This triple mechanism is what sets Retatrutide apart from all other compounds in its class and is responsible for the exceptional results seen in Phase 2 clinical trials.

How Does Retatrutide Work?

Each receptor targeted by Retatrutide plays a distinct role in metabolic regulation:

GLP-1 Activation

GLP-1 receptor activation slows gastric emptying which reduces appetite and caloric intake. It also stimulates insulin secretion in a glucose-dependent manner — meaning it only triggers insulin release when blood sugar is elevated, reducing the risk of hypoglycaemia.

GIP Activation

GIP activation works synergistically with GLP-1 to enhance insulin secretion. Importantly, GIP also activates receptors in adipose tissue which may contribute to improved fat metabolism and redistribution.

Glucagon Receptor Activation

This is the component that distinguishes Retatrutide from Tirzepatide (Mounjaro/Zepbound). Glucagon receptor activation increases energy expenditure — effectively increasing the rate at which the body burns calories at rest. It also promotes hepatic fat oxidation which may benefit liver health.

The combination of reduced caloric intake, enhanced insulin sensitivity and increased energy expenditure creates a powerful triple effect that clinical trials suggest may exceed the results of any current approved medication.

Retatrutide Clinical Trial Results

The Phase 2 clinical trial published in the New England Journal of Medicine (2023) produced remarkable results that attracted global attention from researchers and medical professionals.

For comparison, Semaglutide (Ozempic/Wegovy) achieves approximately 15% body weight reduction over 68 weeks and Tirzepatide (Mounjaro) achieves approximately 22% over 72 weeks. Retatrutide achieved comparable or superior results in significantly less time.

Available Forms and Doses

Retatrutide is currently available as a research compound in the following formats:

• Retatrutide 5mg — vial format for research use
• Retatrutide 6mg — vial format
• Retatrutide 10mg — vial format
• Retatrutide 12mg — vial format
• Retatrutide 20mg — R&D only, vial and bundle formats
• Retatrutide 40mg — injection pen format, 12-16 week supply

Retatrutide vs Semaglutide vs Tirzepatide

Side Effects of Retatrutide

The most commonly reported side effects in clinical trials were gastrointestinal in nature and were generally mild to moderate and transient:

• Nausea — most common, particularly at treatment initiation
• Vomiting — typically self-resolving
• Diarrhoea
• Constipation
• Decreased appetite

These effects were dose-dependent and most common during dose escalation. The incidence reduced significantly after the initial weeks of treatment in most study participants.

Where to Buy Retatrutide Online

Retatrutide is available as a research compound from licensed suppliers. When purchasing Retatrutide online it is critical to source from a reputable supplier that provides pharmaceutical grade product with a Certificate of Analysis.

GLP1 Peptides stocks Retatrutide in all available doses — 5mg, 6mg, 10mg, 12mg, 20mg and 40mg — with worldwide shipping in 1-3 days and discreet packaging.