For years Peptide Sciences was the default answer to "where do I buy research peptides in the USA". On March 6, 2026 it stopped. Its website now shows a short closure notice and nothing else. This guide explains what happened, why look-alike sites using its name should be avoided, and what a laboratory should ask of any Retatrutide supplier it considers next.
What happened to Peptide Sciences
The company announced that it had "voluntarily" shut down operations and discontinued the sale of its research products. No public FDA warning letter was issued to it. Industry reporting puts its revenue at roughly US$7.4 million per month in December 2025, three months before the closure, so the decision was not commercial. It followed an 18-month escalation of enforcement across the entire research-peptide sector:
- March 2024 – January 2025: Eli Lilly filed an ITC complaint against twelve vendors selling tirzepatide; the ITC issued a general exclusion order blocking tirzepatide imports.
- December 2024: the FDA sent warning letters to Swiss Chems, Prime Peptides, Xcel Peptides and Summit Research for selling GLP-1 receptor agonists as unapproved drugs.
- June 2025: FDA agents raided the Amino Asylum warehouse; the site went offline the same day.
- September 2025: the FDA issued more than fifty warning letters to GLP-1 compounders and vendors in a single wave.
- Late 2025: criminal pleas in peptide distribution cases (Tailor Made Compounding, All American Peptide); the founders of Paradigm Peptides faced federal charges.
- Early 2026: the SAFE Drugs Act was introduced in Congress, and card processors began cutting off research-peptide merchants.
At least seven research-peptide companies closed during 2025. Peptide Sciences chose to exit before enforcement reached it, and Science.bio closed two months earlier for similar reasons.
The copycat sites: "Official Peptide Sciences" is not Peptide Sciences
Within weeks of the closure, a cluster of domains appeared using the Peptide Sciences name, logo and page layout — variations such as "official", "USA", "inc", "labs" or an extra letter in the name. They present themselves as the original store. They are not. Some may ship product of unknown origin; others take payment and ship nothing. There is no way to verify a lot, a COA or a refund policy against a company that no longer exists, so a site trading on that name has, by definition, no accountable operator behind it. If the domain is not exactly peptidesciences.com, it is not Peptide Sciences — and peptidesciences.com itself sells nothing.
What to require from a Retatrutide supplier now
The vendors that closed were, for the most part, not closed for poor quality. But the ones that replaced them range from serious laboratories to anonymous drop-shippers, and Retatrutide is the compound most often counterfeited or under-dosed in independent test rounds. Before ordering, check these five points:
| Check | What to look for |
|---|---|
| Certificate of analysis per lot | HPLC purity, mass-spectrometry identity, lot number and date. The lot number on the COA must match the number printed on the vial. A generic "99% purity" badge with no lot is not a COA. |
| A real company | A registered US legal entity, a physical state of operation, a working support e-mail and phone. Anonymous sites cannot honour a claim. |
| Domestic shipping | Ships from inside the USA with tracking. Imported GLP-class peptides are exposed to the ITC exclusion order and customs seizure. |
| Stated dosage sizes | Vial content stated in mg with a matching COA; "blended" or unlabelled GLP vials are a red flag. |
| No medical claims | A supplier that advertises weight-loss results is advertising an unapproved drug, and is the kind of site that draws the enforcement described above. |
Retatrutide at Claude Aminos
Claude Aminos is operated by Zeus Health Group LLC, a Florida company, and ships from the USA by USPS with tracking. Retatrutide is supplied lyophilized in single vials of 30 mg and 50 mg and in packs of three, with the lot number on every label and the certificate of analysis for the lot available on the verification page. Support is reachable by e-mail and phone on the contact page.
| Product | Content | Price |
|---|---|---|
| Retatrutide 30 mg | 1 vial, lyophilized | US$235 |
| Retatrutide 50 mg | 1 vial, lyophilized | US$295 |
| Retatrutide 30 mg — pack of 3 | 3 vials | US$579 |
| Retatrutide 50 mg — pack of 3 | 3 vials | US$778 |
| Retatrutide 30 mg — pack of 5 | 5 vials, laboratory pack | US$500 while stock lasts (regular US$1,175) |
For comparison, of the four largest US research-peptide vendors still operating in September 2026, only one lists Retatrutide at all, at US$275 for 35 mg and US$400 for 60 mg. Reconstitution supplies — bacteriostatic water in 3 mL and 10 mL — are stocked alongside, and the reconstitution calculator covers the arithmetic.
Frequently asked
Did Peptide Sciences shut down? Yes, on March 6, 2026, by its own announcement. The site remains online only to display the notice.
Is Peptide Sciences coming back? Nothing has been announced. Its notice explicitly disowns any site claiming to be affiliated with it.
Are the "Official Peptide Sciences" stores real? No. They are unauthorized look-alikes. Do not enter payment details on them.
How do I check a vendor's COA? Ask for the COA of the lot on your vial, confirm HPLC purity and mass-spec identity are both present, and match the lot number to the label.
Shop Retatrutide and reconstitution supplies
Retatrutide 30 mg Retatrutide 50 mg Pack of 5 — US$500 Lot COA verification 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.