Retatrutide and tirzepatide are both incretin-class peptides studied in metabolic research, but they are different molecules: tirzepatide is a dual GIP/GLP-1 receptor agonist that is FDA-approved as a prescription drug, while retatrutide is an investigational triple GIP/GLP-1/glucagon receptor agonist still in phase 3 trials. Aegis Bio supplies both as research-use-only lyophilised peptides with a certificate of analysis per lot.
Key facts
- Receptors: tirzepatide acts at GIP and GLP-1 receptors; retatrutide adds the glucagon receptor, which is why it is called a triple agonist.
- Status: tirzepatide has been approved by the FDA as a prescription medicine since 2022; retatrutide (Eli Lilly, LY3437943) is not approved for any use and remains in phase 3 (TRIUMPH programme).
- Structure: both are roughly 39-residue peptides built on a GIP-like backbone with a C20 fatty diacid on a lysine side chain. Molecular weight is about 4,731 for retatrutide and 4,813 for tirzepatide.
- Format at Aegis Bio: lyophilised powder, single vials and 10-vial kits, ≥99% HPLC purity specification, COA on request.
- Price: retatrutide 10 mg single vial $25, tirzepatide 20 mg single vial $47; 10 mg kits from $113 (tirzepatide) and $100 (retatrutide).
What is the difference between retatrutide and tirzepatide?
Mechanistically, one receptor. Tirzepatide was engineered as an unbalanced dual agonist with stronger GIP than GLP-1 activity. Retatrutide keeps GIP and GLP-1 activity and adds glucagon receptor agonism. The added glucagon component is the reason retatrutide is studied as a class of its own rather than as a tirzepatide follow-on.
For a laboratory the practical differences are documentation and availability. Tirzepatide is a characterised, approved molecule with an extensive public data package, which makes it a convenient reference agonist. Retatrutide is newer, its reference standards are scarcer, and lot-to-lot documentation matters more because there is less public benchmark to compare against.
Sequence, structure and analytics
| Property | Retatrutide | Tirzepatide |
|---|---|---|
| Receptor activity | GIP, GLP-1, glucagon | GIP, GLP-1 |
| Developer / code | Eli Lilly, LY3437943 | Eli Lilly, LY3298176 |
| Regulatory status | Investigational, phase 3 | FDA-approved prescription drug |
| Approximate MW | 4,731 g/mol | 4,813 g/mol |
| Lipidation | C20 fatty diacid | C20 fatty diacid |
| Typical purity spec | ≥99% (HPLC) | ≥99% (HPLC) |
| Identity check | Mass spectrometry | Mass spectrometry |
Both peptides are large and lipidated, so on reverse-phase HPLC they elute late and can show a closely eluting shoulder if oxidised. Ask for the chromatogram, not just the purity figure; see reading an HPLC chromatogram.
Storage and handling
Lyophilised material keeps at −20 °C, protected from light and moisture. Once reconstituted, both are used within days at 2–8 °C and should not be repeatedly frozen. Bacteriostatic water is the usual diluent for a multi-draw vial in a research setting. Full guidance is in storing lyophilised research peptides and reconstitution and dilution math.
What retatrutide and tirzepatide cost
Prices below are the live Aegis Bio catalog and update automatically. Shipping is $20 for a cart of single vials and $45 when a kit is included; single vials ship free alongside a kit, and international orders ship for a flat $80. WELCOME10 takes 10% off a first order.
| Item | Price | Per vial | Per mg |
|---|---|---|---|
| Retatrutide 10 mg × 1 vial | $25 | $25.00 | $2.50 |
| Retatrutide 10 mg × 10 vials | $100 | $10.00 | $1.00 |
| Retatrutide 20 mg × 10 vials | $179 | $17.90 | $0.895 |
| Tirzepatide 20 mg × 1 vial | $47 | $47.00 | $2.35 |
| Tirzepatide 10 mg × 10 vials | $113 | $11.30 | $1.13 |
| Tirzepatide 20 mg × 10 vials | $134 | $13.40 | $0.670 |
Per milligram, tirzepatide kits are the lower-cost reference material and retatrutide carries a premium because supply is thinner. For comparison, retatrutide 10 mg single vials are commonly listed at $45–$89 by other research vendors, and 10-vial kits from $90 to several hundred dollars.
Which one to order
If the work needs an approved, extensively characterised dual agonist as a comparator, tirzepatide. If the work is specifically about glucagon receptor co-agonism or the triple-agonist class, retatrutide. Many labs run both side by side; the current offers page lists any reduced kit or vial prices.
All materials are supplied for in-vitro laboratory research use only. Nothing on this page is a therapeutic claim, and no dosing guidance is provided. See what research use only means.