Retatrutide vs Tirzepatide: A Research Comparison

Retatrutide and tirzepatide are two of the most studied incretin-based peptides in metabolic research. Both are long-acting synthetic peptides based on the GIP peptide sequence, but they act on different combinations of receptors. This article compares them for laboratory researchers. All products mentioned are supplied strictly for research use only and are not for human or veterinary use.

Receptor targets

Tirzepatide is a dual agonist of the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. Retatrutide, also known as LY3437943, adds a third target: it is a triple agonist of the GIP, GLP-1 and glucagon receptors. That extra glucagon-receptor activity is the main reason researchers study the two side by side, for example in comparative receptor-binding assays, signalling-pathway studies and in-vitro models of energy metabolism.

Molecular design

Both compounds are synthetic peptides carrying a fatty-acid side chain, which promotes albumin binding and extends their half-life in experimental systems. Tirzepatide is a 39-amino-acid peptide with a molecular weight of approximately 4,813 Da. Because the two peptides share a similar design, they are usually handled, stored and reconstituted in the same way in the laboratory.

Development status

Tirzepatide is the active ingredient in licensed medicines, while retatrutide is an investigational compound that has been evaluated in clinical trials. Research-grade material supplied by Dr Peptide is neither: it is a laboratory reagent for in-vitro research only and must not be used in humans or animals.

Formats available in the UK

• Retatrutide: lyophilised vials in 5mg and 20mg, and pre-filled 40mg pens from Alluvi and Synedica.
• Tirzepatide: a lyophilised 20mg vial and the Alluvi Tirzepatide 40mg pre-filled pen.

Not sure which format suits your protocol? See our guide to peptide pens vs lyophilised vials, and for detailed specifications read tirzepatide research compound specifications.

Storage and documentation

Store lyophilised vials refrigerated or frozen and protected from light, and keep pens refrigerated. A Certificate of Analysis is available on request, and orders ship from the UK for delivery to the UK mainland, usually within 1–3 business days of dispatch.

Browse the full GLP-1 research peptide range. All products are supplied strictly for laboratory research use only and are not for human or veterinary use.