Semaglutide

Semaglutide is a long-acting glucagon-like peptide-1 receptor agonist (GLP-1 RA) developed by Novo Nordisk. It is a 31-amino acid peptide analogue of human GLP-1 with two key modifications: an alpha-aminoisobutyric acid substitution at position 8 that confers resistance to dipeptidyl peptidase-4 (DPP-4) degradation, and a C18 fatty diacid chain attached to lysine at position 26 via a linker that enables non-covalent albumin binding, extending the half-life to approximately 7 days.

Semaglutide is approved for type 2 diabetes (Ozempic, subcutaneous; Rybelsus, oral) and chronic weight management (Wegovy, subcutaneous). It is among the most commercially successful and clinically studied peptide therapeutics, with major outcomes trials demonstrating benefits in glycemic control, weight reduction, and cardiovascular risk reduction. The oral formulation (Rybelsus) represents a significant pharmaceutical achievement as the first oral GLP-1 RA, using a sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) absorption enhancer.

Semaglutide activates the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, hypothalamic neurons, gastric parietal cells, and cardiovascular tissue. In the pancreas, GLP-1R activation potentiates glucose-dependent insulin secretion while suppressing glucagon release from alpha cells — the glucose-dependent nature of this effect means hypoglycemia risk is low when used as monotherapy.

The weight loss mechanism operates primarily through central appetite regulation. Semaglutide crosses the blood-brain barrier and acts on GLP-1 receptors in the hypothalamic arcuate nucleus and other appetite-regulating centers, reducing hunger, increasing satiety, and decreasing food cravings. It also slows gastric emptying, contributing to early satiety. The cardiovascular benefits observed in outcomes trials appear to involve anti-inflammatory effects on vascular endothelium, reduced arterial plaque inflammation, and improvements in lipid profiles, blood pressure, and endothelial function — mechanisms that are partially independent of weight loss and glycemic improvement.