Overview

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist based on the native GLP-1(7-37) sequence with modifications that resist degradation by dipeptidyl peptidase-4 (DPP-4) and extend its half-life. A C-18 fatty diacid side chain attached via a spacer promotes reversible albumin binding, giving semaglutide a half-life of approximately one week.

Semaglutide is approved in branded clinical formulations by regulators in many jurisdictions for adults with type 2 diabetes (Ozempic, Rybelsus) and for chronic weight management (Wegovy). This profile summarises the published pharmacology and clinical literature for scientific reference; it is not a treatment recommendation, and use of research-grade material differs materially from use of a regulated pharmaceutical formulation.

Mechanism (as reported)

  • GLP-1 receptor agonism. Semaglutide binds and activates the GLP-1 receptor, expressed on pancreatic β-cells, α-cells, gastric smooth muscle, and multiple areas of the central nervous system including the hypothalamus.
  • Glucose-dependent insulin release. Activation of β-cell GLP-1 receptors potentiates glucose-dependent insulin secretion.
  • Glucagon suppression. Studies indicate GLP-1 agonism suppresses inappropriate glucagon release.
  • Slowed gastric emptying. Semaglutide slows gastric emptying, contributing to satiety and reduced post-prandial glucose excursions.
  • Central satiety effects. Research indicates semaglutide acts on hypothalamic and brainstem GLP-1 receptors to reduce appetite.

Research findings

  • STEP program (weight management). The STEP trials reported approximately 15% body-weight reduction from baseline over 68 weeks in adults with obesity treated with 2.4 mg weekly (Wilding et al., 2021; PMID 33567185).
  • SUSTAIN program (type 2 diabetes). The SUSTAIN trials reported HbA1c reductions of approximately 1.5–1.8 percentage points with once-weekly dosing (multiple publications).
  • SELECT trial (cardiovascular outcomes). Semaglutide 2.4 mg weekly was reported to reduce the primary composite cardiovascular endpoint by approximately 20% in adults with established cardiovascular disease and overweight/obesity without diabetes (Lincoff et al., 2023; PMID 37952131).

Common dosing (as reported)

The dosing schedule reported in the clinical literature is a dose-escalation pattern beginning at 250 mcg once weekly for four weeks, escalating stepwise (typically 500 mcg → 1,000 mcg → 1,700 mcg → 2,400 mcg) at four-week intervals to reduce the incidence of gastrointestinal side effects, which are dose-dependent and most pronounced during escalation.

Reconstitution

Research-grade lyophilised semaglutide is typically reconstituted with bacteriostatic water. A common reconstitution reported in research writeups is 5 mg of peptide in 2 mL bacteriostatic water, producing a 2,500 mcg/mL solution. At this concentration, a 250 mcg starting research dose corresponds to 0.1 mL, or 10 units on a U-100 insulin syringe.

Note: regulated pharmaceutical formulations of semaglutide are supplied pre-formulated at defined concentrations and are not reconstituted by the end user. Any comparison to those formulations should account for differences in excipients, sterility validation, and manufacturing.

Storage

Regulated formulations of semaglutide are stored refrigerated at 2–8 °C. Research-grade reconstituted semaglutide is generally stored under the same conditions.

Reported adverse effects (from clinical trials)

Clinical trial data report gastrointestinal effects (nausea, vomiting, diarrhea, constipation) as the most common, particularly during dose escalation. Less common but clinically noted effects in the labeling include pancreatitis, gallbladder disease, and — based on rodent studies — a boxed warning regarding medullary thyroid carcinoma. These are drawn from regulated-drug labels and clinical trial reports.

Common stacks

References

  • Wilding, J. P. H., et al. (2021). “Once-weekly semaglutide in adults with overweight or obesity.” New England Journal of Medicine, 384(11). PMID 33567185.
  • Lincoff, A. M., et al. (2023). “Semaglutide and cardiovascular outcomes in obesity without diabetes.” New England Journal of Medicine, 389(24). PMID 37952131.
  • Marso, S. P., et al. (2016). “Semaglutide and cardiovascular outcomes in patients with type 2 diabetes.” New England Journal of Medicine, 375(19). PMID 27633186.
  • Knudsen, L. B., & Lau, J. (2019). “The discovery and development of liraglutide and semaglutide.” Frontiers in Endocrinology, 10. PMID 31031702.