Retatrutide vs tirzepatide: the key differences
Updated October 2026
Side by side
| Tirzepatide | Retatrutide | |
|---|---|---|
| Developer · code | Eli Lilly · LY3298176 | Eli Lilly · LY3437943 |
| Receptor targets | GIPR + GLP-1R (dual agonist) | GIPR + GLP-1R + GCGR (triple agonist) |
| Structure | 39-amino-acid peptide based on the GIP sequence, with a C20 fatty diacid side chain | Synthetic peptide with non-natural amino acids (Aib) and a C20 fatty diacid side chain |
| Interval in clinical studies | Once weekly | Once weekly |
| Half-life | About 5 days | Long (albumin binding through the fatty diacid) |
| Status (October 2026) | Approved medicine: Mounjaro (FDA May 2022, EU Sept 2022) and Zepbound (FDA Nov 2023) | Investigational: Phase 3 (TRIUMPH programme). Not approved by the FDA or the EMA |
| Clinical programmes | SURPASS (type 2 diabetes), SURMOUNT (weight management) | TRIUMPH |
| Peptworks research vial | 10 mg · €25.00/vial (box of 10) · €39.90 (4-pack) | 10 mg · €35.00/vial (box of 10) · €55.90 (4-pack) |
Dual vs triple agonism: what the extra receptor means
Both molecules mimic incretin hormones. Tirzepatide was built around two targets, the GIP and GLP-1 receptors. Retatrutide adds agonism at the glucagon receptor (GCGR). In the research literature, glucagon-receptor activity is associated with energy expenditure and hepatic lipid metabolism, which is why retatrutide is studied as one molecule acting on three receptors at once. For a lab this means different questions: tirzepatide is the reference for dual GIP/GLP-1 agonism, retatrutide for triple agonism, and semaglutide (GLP-1R only) is the usual single-receptor comparator.
Structure: two lipidated peptides
Tirzepatide is a 39-amino-acid linear peptide based on the native GIP sequence, with a C20 fatty diacid attached to a lysine side chain through a linker; binding to albumin extends its half-life to about 5 days. Retatrutide follows the same design logic: a synthetic peptide with non-natural amino acids such as Aib and a C20 fatty diacid side chain that promotes reversible albumin binding.
Development status (October 2026)
Tirzepatide is an approved medicine: Mounjaro for type 2 diabetes (FDA, May 2022; EU, September 2022) and Zepbound for weight management (FDA, November 2023). Retatrutide is not approved anywhere as a medicine: its Phase 3 programme, TRIUMPH, has reported results in 2025 and 2026. Outside approved medicines, both compounds are only supplied as laboratory research reagents.
Which one should a research catalogue stock?
Retatrutide is the newest of the three and the one we are asked about most; tirzepatide remains the reference dual agonist. Many labs and resellers keep both, plus semaglutide as a comparator. You can mix them in one order: the 4-pack price applies from 4 vials, the box price from 10 vials of each reference, and shipping is free from €500.
Research-grade retatrutide and tirzepatide from EU stock
Unbranded (white-label) lyophilized vials, tested per batch by an independent lab and shipped from EU stock with no customs in 3–5 days. Payment in crypto (USDC, USDT or Bitcoin) is what keeps the price this tight.
Frequently asked questions
Is retatrutide approved?
No. As of October 2026 retatrutide is an investigational compound in Phase 3 development (TRIUMPH programme). It is not an approved medicine in the EU or the US.
Is tirzepatide the same as Mounjaro?
Tirzepatide is the active substance of the medicines Mounjaro and Zepbound. Peptworks supplies tirzepatide only as a lyophilized research reagent, not as a medicine.
What does the glucagon receptor add in retatrutide?
Retatrutide also activates the glucagon receptor (GCGR). In the research literature, glucagon-receptor activity is linked to energy expenditure and liver lipid metabolism; that third target is the main pharmacological difference from tirzepatide.
Can I order both in one shipment?
Yes. Mix references freely: 4-pack price from 4 vials, box price from 10 vials of each reference, and free shipping from €500 inside the EU with no customs.
How do I pay?
In crypto: USDC or USDT on Polygon or Base, or Bitcoin. Paying in crypto is what keeps our prices this tight, with no card or bank fees.
Are these products for human use?
No. Peptworks supplies them strictly as laboratory research reagents (Research Use Only). They are not medicines or supplements and are not for human or animal consumption.
Research Use Only. This guide describes published pharmacology and regulatory status for research purposes; it is not medical advice and does not describe any use in humans.