Semaglutide

Semaglutide is a long-acting GLP-1 receptor agonist comprising 31 amino acids with 94% structural homology to native human GLP-1. Three critical modifications confer its pharmacological advantages: substitution of alanine at position 8 with α-aminoisobutyric acid (Aib) to prevent DPP-4 cleavage, substitution of lysine at position 34 with arginine, and acylation of lysine at position 26 with a C18 fatty-diacid chain via a linker. This C18 moiety enables reversible albumin binding, extending the plasma half-life to approximately 165 hours and allowing once-weekly subcutaneous administration. Mechanistically, semaglutide binds and activates the GLP-1 receptor on pancreatic beta cells, stimulating glucose-dependent insulin secretion while simultaneously suppressing glucagon release and slowing gastric emptying. In the central nervous system, receptor activation in the hypothalamus and brainstem reduces appetite and food intake. The SUSTAIN clinical trial program documented robust glycemic control in type 2 diabetes, while the STEP program demonstrated mean body weight reductions of 15.2% over 68 weeks at 2.4 mg weekly dosing, establishing semaglutide as a leading agent in obesity research. Cardiovascular research has demonstrated semaglutide significantly reduces the risk of major adverse cardiovascular events (MACE) — including non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death — in high-risk populations. The SELECT trial (2023) further confirmed cardiovascular benefit in people with obesity without diabetes, broadening the research scope beyond glycemic regulation. Additional areas of investigation include renal protection, non-alcoholic steatohepatitis (NASH), and neurodegeneration.