Peptides are short chains of amino acids — the same building blocks that make up proteins. They differ from proteins primarily in length: peptides typically contain fewer than 50 amino acids. In the body, naturally occurring peptides serve as signaling molecules, hormones, and neurotransmitters.

Researchers study peptides through in-vitro (cell culture) experiments, animal models, and — for approved compounds — human clinical trials. Each stage of research provides different types of information. In-vitro results are preliminary and cannot be directly applied to humans.

Endogenous peptides are produced naturally by the body (e.g., insulin). Synthetic peptides are manufactured in laboratories to mimic, modify, or block natural peptide activity. Research peptides are synthetic compounds used to study biological pathways in controlled settings.

FDA-approved peptides (like insulin or oxytocin) have passed rigorous clinical trials establishing safety and efficacy profiles. Research peptides have not completed this process and are approved only for in-vitro laboratory investigation — not for human administration.

Research-use-only compounds are sold exclusively for scientific investigation in laboratory settings. They are not intended, labeled, or approved for human consumption. This designation reflects their regulatory status and the current state of scientific knowledge.