Semaglutide

Semaglutide (development code NN9535) is a synthetic long-acting glucagon-like peptide-1 (GLP-1) receptor agonist first described by Lau and colleagues in 2015. It is derived from the native human incretin GLP-1(7-37) and engineered with an α-aminoisobutyric acid substitution at position 8 (Aib8), an arginine substitution at position 34 (Arg34) and a lysine-26 acylation with a C18 fatty-di-acid via a γGlu-2xOEG spacer.

These modifications produce two convergent effects: resistance to dipeptidyl peptidase-4 (DPP-4) cleavage and reversible non-covalent binding to serum albumin. Together they extend the plasma half-life of Semaglutide to approximately one week in humans, supporting once-weekly subcutaneous dosing and a distinct oral formulation co-administered with the absorption enhancer SNAC.

Semaglutide is one of the most extensively studied GLP-1 receptor agonists in the published clinical literature, with landmark outcome trials in type 2 diabetes (SUSTAIN-6), obesity (STEP-1), cardiovascular disease in obesity without diabetes (SELECT) and chronic kidney disease in type 2 diabetes (FLOW).

Oxford Research Peptides supplies Semaglutide strictly as a reference standard for in-vitro laboratory research. Nothing on this page constitutes medical advice or endorses any therapeutic use of research-grade material. Approved Semaglutide medicines (Ozempic, Wegovy, Rybelsus) are prescribed by qualified clinicians under MHRA authorisation.

Semaglutide is a 31-residue linear peptide with one lysine side-chain modification and no disulfide bonds. Its full name is N26-[2-(2-[2-(2-[2-(2-[4-(17-carboxyheptadecanoylamino)-4(S)- carboxybutyrylamino]ethoxy)ethoxy]acetylamino)ethoxy]ethoxy) acetyl]-[Aib8, Arg34]GLP-1(7-37).

Semaglutide is a selective agonist of the GLP-1 receptor. Its modifications extend duration of action; the receptor pharmacology at GLP-1R remains close to native GLP-1. GLP-1R is a class B (secretin-family) G-protein-coupled receptor coupled predominantly to Gαs, activating adenylyl cyclase and generating cyclic AMP (cAMP) as the primary second messenger.

• cAMP / PKA signalling: Gαs coupling elevates intracellular cAMP, activating protein kinase A and downstream transcriptional and metabolic effectors.
• cAMP / EPAC2: A parallel cAMP effector, EPAC2, contributes to glucose-dependent insulin exocytosis from pancreatic β-cells.
• β-arrestin recruitment: Class B GPCR agonists also recruit β-arrestin, contributing to receptor internalisation and pathway-specific signalling; the balance of G-protein and arrestin engagement is an active area of biased-agonism research.
• Central appetite modulation: Preclinical rodent work maps Semaglutide activity to distributed neural circuits spanning brainstem and hypothalamic POMC / NPY populations, consistent with reduced food intake in vivo.

Two features drive Semaglutide's pharmacokinetics: DPP-4 resistance conferred by the Aib8 substitution, and albumin binding conferred by the C18 fatty-di-acid side chain attached at lysine-26 through a γGlu-2xOEG linker.

• Plasma half-life (human): approximately 165–184 h (~1 week) after subcutaneous administration.
• Steady state: achieved after 4–5 weeks of once-weekly dosing (5 half-lives).
• Bioavailability (SC): ~89% of the injected dose.
• Oral formulation: co-administered with SNAC (salcaprozate sodium), which transiently raises local pH in the stomach and enables absorption; oral bioavailability is low (< 1%) but pharmacologically sufficient with daily dosing.
• Elimination: primarily proteolytic; renal and biliary excretion of small peptide fragments.

Semaglutide reference standards are supplied lyophilised. Standard laboratory practice for acylated GLP-1 analogues applies: careful aseptic technique, low-binding plasticware, and awareness that albumin-binding acylated peptides are surface-active and can aggregate on hydrophobic surfaces at low concentrations.

Reconstitute per the laboratory SOP. A general procedure is documented in the Laboratory Reconstitution Guide. The summary below applies to Semaglutide as an acylated GLP-1 analogue:

1. Equilibrate the sealed vial to room temperature.
2. Introduce sterile or bacteriostatic water slowly against the vial wall.
3. Swirl gently — do not vortex — to protect the peptide backbone.
4. Allow complete dissolution; a faint opalescence at high concentration is consistent with the surface-active fatty-acid side chain.
5. Aliquot into low-binding vials; label with peptide, concentration, batch, date and analyst.