FDA warns two sellers of retatrutide as a ‘research peptide’

The Food and Drug Administration issued warning letters dated March 31, 2026 to two online sellers, Gram Peptides (P.O. box in Rancho Santa Fe, California) and Prime Sciences (Scottsdale, Arizona). Both letters say FDA reviewed the companies’ websites “from January to March 2026.”

What each letter covers

Gram Peptides. FDA lists “Retatrutide” (which the firm also called “GLP-1-R peptide”), “Tirzepatide” (“GLP-2 peptide”) and “Bacteriostatic Water for Injection.” The site labeled products “Research Use Only” and “not intended for human consumption, medical use, or veterinary use.” FDA wrote that “evidence obtained from your website establishes that your products are intended to be drugs for human use.”

Prime Sciences. FDA lists “Cagrilintide,” “GLP1-R,” “GLP1-S,” “GLP1-T,” “Mazdutide,” and “BAC water.” The site used “laboratory research purposes only” and similar language. FDA reached the same conclusion.

Coded names do not change the analysis

Both companies sold GLP-1-class products under abbreviations rather than drug names. The letters still treat them as the named drugs, such as retatrutide and tirzepatide. The same coding appears in the August 2026 letters (report).

The injectable warning

Both letters include language that FDA also used in its August letters: injectable products “are delivered directly into the body, sometimes directly into the bloodstream, and therefore, bypass some of the body’s key defenses against toxins and microorganisms.” This is why sterility and endotoxin testing matter for anything meant to be injected. A purity number on a certificate of analysis says nothing about them. See endotoxin testing explained.

Status today

On October 19, 2026, both homepages redirected to account-login pages. Details are on the Gram Peptides and Prime Sciences status logs.