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Peptide

A short chain of amino acids: the molecular structure of the natural hormones GLP-1 medications mimic, and of most of the medications themselves.

Updated Sep 26, 2026

A peptide is a short chain of amino acids linked together, smaller than a full protein. GLP-1, GIP, and glucagon are all naturally occurring peptide hormones, and most GLP-1 medications (semaglutide, tirzepatide, liraglutide, etc.) are themselves synthetic peptides engineered to mimic and extend the action of these natural hormones in the body.

The exception is orforglipron (Foundayo), approved in April 2026. It activates the same GLP-1 receptor but is a small-molecule drug, not a peptide (Foundayo prescribing information (external link)).

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