Retatrutide

Definition

Retatrutide is an investigational agonist at three receptors at once — the glucose-dependent insulinotropic polypeptide receptor, the GLP-1 receptor, and the glucagon receptor. It is a further step along the line that runs from single-agonist to dual-agonist incretin drugs, and it is in active late-stage development.

It is also sold, today, as research-use-only material. This index tracks it because that combination — a real drug candidate with a real trial program and no lawful route to a person outside a trial — is the position readers most often misread.

Evidence

The trial record exists and it is the sponsor's. Across two name variants PubMed returns 178 indexed records, of which 109 carry the Humans subject heading, 8 the clinical-trial publication type, and 7 the randomized-controlled-trial type ^[1]. All eight were opened and read, and every one belongs to the development program: a phase 1b multiple-ascending-dose trial in type 2 diabetes, phase 2 trials in obesity and in type 2 diabetes, a phase 2a trial in metabolic dysfunction-associated steatotic liver disease, body-composition and lipid substudies, and a phase 3 trial ^[1].

The phase 2 obesity trial is the result the market reacted to and the one most often quoted secondhand ^[2]; a phase 3 trial in people with type 2 diabetes and inadequate glycemic control on diet and exercise has since been published ^[3]. Reporting either as evidence of approval is the error this page exists to prevent, and the distinction is not subtle: a trial establishes what a compound does under study conditions, and an approval establishes that a specific product may be sold to be used.

The eight trial-type records are also the reason a count alone tells a reader nothing about legality. Ipamorelin has two and no route; retatrutide has eight and no route; semaglutide has hundreds and an approval. The number that decides the legal question is not in the literature at all.

Lawful access

There is no lawful United States supply route outside a clinical trial. No approved product containing retatrutide exists: a query of Drugs@FDA by active ingredient returns no records for it, in the same run in which the same query returned records for bremelanotide and for liraglutide and returned none for a deliberately invented ingredient name ^[4].

FDA has stated the compounding position in its own words rather than leaving it to inference: retatrutide and cagrilintide cannot be used in compounding under federal law, they are not components of FDA-approved drugs, and they have not been found safe and effective for any condition ^[5]. The substance appears in no category of the section 503A bulks list published on May 14, 2026, and it has never been nominated for one ^[6].

The agency has also acted on research-use-only sales. In March 2026 it issued warning letters to two firms whose websites offered retatrutide, finding the products to be unapproved new drugs; both letters state that despite labeling marketing the products for research use only and not for human consumption, evidence obtained from the firms' own websites establishes that the products are intended to be drugs for human use ^[7][8]. This index records those letters as disclosure of what FDA has stated and adjudicates no business. The research-only page explains what the labeling posture is and is not.

Related molecules

Retatrutide sits with the GLP-1 receptor agonists, where it is the only member without an approval: semaglutide and tirzepatide are approved with their shortages resolved, and liraglutide is approved and still listed in shortage. The human trial record prints this molecule's eight trials beside molecules with none, which is the clearest way to see that the trial count and the legal position are separate facts.

Elsewhere in this index