Research Guides

What do peptides do? Peptides are short chains of amino acids, the same building blocks that make up larger proteins, just fewer of them strung together. In the body, many peptides act as signaling molecules, carrying information between cells and tissues the way a hormone does: insulin and glucagon are both peptides, and so are…

The short answer Selank is a synthetic heptapeptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. In Russia, it has been registered as a prescription nasal spray for generalized anxiety disorder and neurasthenia since 2011, and it appears on that country’s official register of vital and essential medicines. It has…

The one-line answer Cagrilintide and retatrutide are both unapproved, investigational peptides from different companies, at different stages of the FDA process. Cagrilintide is already part of a filed application, but only as one half of a combination product, CagriSema, that Novo Nordisk submitted in December 2025. Retatrutide has not been filed at all; Eli Lilly…

The short answer Cagrilintide is a synthetic, long-acting analogue of human amylin, developed by Novo Nordisk. It is not an FDA-approved drug on its own. Novo Nordisk filed for FDA approval in December 2025, but that filing is for a fixed-dose combination product called CagriSema, not for cagrilintide by itself. As of this writing, cagrilintide…

Research use only. Peptides supplied by Peptryn are sold strictly for in vitro and preclinical laboratory research. They are not approved by the FDA for human or veterinary use, and nothing here is medical advice, a dosing recommendation, or an instruction for self-administration. This guide summarizes the published record and what regulators have said about…

The short answer Published trial data puts retatrutide’s half-life at approximately 6 days. That figure comes from the Phase 2 trial results Eli Lilly published in the New England Journal of Medicine in 2023, the same study that first reported retatrutide’s pharmacokinetics in detail. What half-life means Half-life is a pharmacology measurement, not a usage…

The one-line answer Semaglutide and tirzepatide are FDA-approved drugs. Retatrutide is not approved anywhere and remains an investigational compound in clinical trials. That single difference in regulatory status is the most important thing to understand before comparing anything else about the three. Approval status and brand names Compound Status Approved brand names Developer Semaglutide FDA-approved…

The short answer Retatrutide is not FDA-approved. It is an investigational peptide, meaning it is still going through the clinical trial process the FDA requires before any drug can be sold for human use. Eli Lilly, the company developing it, said on July 23, 2026 that it plans to file an approval application with the…

BPC-157 explained: what it is, what animal and human studies show, half-life, FDA and WADA status, and five checks for a vial’s certificate of analysis.

Popular peptides ranked by US search volume, with FDA status and what the evidence shows for tirzepatide, retatrutide, CJC-1295, MOTS-c, SS-31 and more.