If your laboratory sourced Retatrutide from Peptide Sciences, you have been looking for a replacement since March. The search is harder than it should be, because the same closure that removed the largest US vendor also produced a wave of stores borrowing its name. This page sets out the facts of the closure, the enforcement climate that caused it, and a short checklist for qualifying whoever you order from next.
The closure, in dates
Peptide Sciences posted a brief notice on March 6, 2026: operations voluntarily shut down, all research products discontinued. No products remain on the domain and no reopening has been announced. The company was not small — trade reporting estimates about US$7.4 million in monthly sales at the end of 2025 — which makes the reason plain: it left before regulators reached it. The pressure had been building for a year and a half:
- Eli Lilly's ITC case against a dozen tirzepatide sellers (filed March 2024) ended in a general exclusion order on tirzepatide imports in January 2025.
- In December 2024 the FDA issued warning letters to four peptide retailers — Swiss Chems, Prime Peptides, Xcel Peptides and Summit Research — for marketing GLP-1 agonists as unapproved drugs.
- Amino Asylum's warehouse was raided by FDA agents in June 2025 and the store went dark the same day.
- A wave of more than fifty FDA warning letters reached GLP-1 compounders and vendors in September 2025.
- Guilty pleas and federal charges followed at the end of 2025 (Tailor Made Compounding, All American Peptide, the founders of Paradigm Peptides), and card processors began dropping research-peptide merchants.
- Science.bio closed in January 2026; Peptide Sciences in March; the SAFE Drugs Act, aimed squarely at "research" copies of approved drugs, entered Congress the same quarter.
"Official Peptide Sciences" — a warning
Search for the old name today and you will find several stores using it — the same logo, a similar layout, and a domain that adds "official", "usa", "inc", "labs", ".shop" or a doubled letter. None of them is the company that closed. Whoever runs them is anonymous by design, which means no lot can be traced, no certificate verified and no order disputed. Do not enter card details on any of them. The only genuine domain is peptidesciences.com, and it sells nothing.
The checklist
Retatrutide is the compound most often flagged in independent test rounds for under-dosing or substitution, so the qualification questions are not academic. Ask every candidate supplier for these six things and walk away from any that cannot produce them:
| Ask for | Pass condition |
|---|---|
| Lot-specific COA | Lot number on the certificate equals the lot number on the vial. HPLC purity and mass-spec identity both present, with laboratory name and date. |
| Legal entity | A named US company, the state it operates from, and a support line that answers. |
| Origin of shipment | Ships from within the United States with tracking. Imports of GLP-class peptides are exposed to the ITC order and customs seizure. |
| Labelled content | Milligrams per vial printed on the label and repeated on the COA; no unlabelled "GLP blend" vials. |
| Lyophilized form | Freeze-dried powder for reconstitution, not pre-mixed solution of unknown age. |
| No therapeutic claims | Pages that promise weight loss are marketing an unapproved drug and invite the enforcement described above — a supplier that does this is a supplier that may not exist next quarter. |
Retatrutide from Zeus Aminos
Zeus Aminos is a US store shipping lyophilized Retatrutide by USPS with tracking. Every vial is labelled with its lot number, and the certificate for that lot can be checked on the verification page. Support is by e-mail and phone via the contact page. Current listings:
| Listing | Content | Price |
|---|---|---|
| Retatrutide 30 mg | 1 vial | US$235 |
| Retatrutide 50 mg | 1 vial | US$295 |
| Retatrutide 30 mg × 3 | 3 vials | US$579 |
| Retatrutide 50 mg × 3 | 3 vials | US$778 |
| Retatrutide 30 mg × 10 — laboratory pack | 10 vials | US$1,000 while the promotion lasts (regular US$2,350) |
Among the four largest US research-peptide retailers still trading in September 2026, only one carries Retatrutide, at US$275 for a 35 mg vial and US$400 for 60 mg. Bacteriostatic water in 3 mL and 10 mL is stocked for reconstitution, and the calculator gives the volumes.
Questions we are asked
When did Peptide Sciences close? March 6, 2026, by its own notice. Nothing has been sold on the domain since.
Which site is the real Peptide Sciences now? None. Every store using the name is unauthorized, by the company's own statement.
What must a Retatrutide COA contain? Matching lot number, HPLC purity, mass-spec identity, laboratory and date.
Does Zeus Aminos ship from the USA? Yes, domestically by USPS with tracking, for research use only.
Order Retatrutide and reconstitution supplies
Retatrutide 30 mg Retatrutide 50 mg Pack of 10 — US$1,000 Verify a lot COA Bacteriostatic water
Sources: peptidesciences.com closure notice; PeptideLaws, "Why did Peptide Sciences shut down"; BioStrata Research, "Peptide Sciences shutdown 2026"; FDA warning-letter records; US International Trade Commission tirzepatide general exclusion order (January 2025). All products on this site are for in-vitro laboratory research only and are not for human or animal use.