Semaglutide (peptide context)
Semaglutide, while primarily known as the active ingredient in Ozempic and Wegovy, is fundamentally a peptide — a 31 amino acid modified GLP-1 analog. Its inclusion in the peptide directory reflects its origin as a peptide therapeutic and its relevance to the peptide therapy community, many of whom access it through compounding pharmacies. Semaglutide represents the most commercially successful therapeutic peptide in history, with annual sales exceeding $20 billion. From a peptide science perspective, semaglutide is a masterwork of molecular engineering. It was designed with three key modifications to native GLP-1: an amino acid substitution at position 8 that resists DPP-4 enzyme degradation, a C18 fatty acid chain at position 26 that enables albumin binding (extending half-life to ~7 days), and an amino acid substitution at position 34 that prevents fatty acid attachment at the wrong position. These modifications transformed a peptide with a 2-minute half-life into one with a 7-day half-life. In the peptide community, compounded semaglutide has become the most discussed and widely used peptide, surpassing even BPC-157 and growth hormone secretagogues. The compounded form typically uses the same amino acid sequence but may differ in formulation, preservatives, and purity compared to the Novo Nordisk branded products. Quality varies significantly between compounding pharmacies, making potency testing and sterility verification critical.