Semaglutide — Canada Research Brief

Mechanism

Semaglutide activates the GLP-1 receptor, a class B G-protein-coupled receptor expressed in pancreatic β-cells, gastric smooth muscle, and hypothalamic appetite circuits. Downstream effects include:

• Glucose-dependent insulin secretion from pancreatic β-cells, which improves postprandial glycaemia without the hypoglycaemia risk of sulfonylureas.
• Glucagon suppression from α-cells.
• Delayed gastric emptying, which flattens postprandial glucose peaks and contributes to early satiety.
• Central appetite suppression via GLP-1 receptor populations in the arcuate nucleus and area postrema.

The fatty-acid side chain on Lys26 binds reversibly to plasma albumin, which protects the peptide from DPP-4 cleavage and renal clearance and gives semaglutide its ~165-hour half-life — the basis for once-weekly dosing.

Clinical evidence

The most-cited dataset for semaglutide in weight management is the STEP programme — eight phase-3 trials published 2021–2023. STEP 1 (Wilding et al., NEJM 2021) reported a mean weight reduction of −14.9% at 68 weeks with once-weekly 2.4 mg subcutaneous dosing versus −2.4% for placebo, in adults with BMI ≥30 or ≥27 with comorbidity.

For cardiovascular safety, SUSTAIN-6 (Marso et al., NEJM 2016) demonstrated a 26% relative risk reduction in the primary MACE composite endpoint in adults with type 2 diabetes at elevated cardiovascular risk.

How Canadian researchers source semaglutide

Canadian labs sourcing research-grade semaglutide should verify three things on every vendor: (1) per-batch HPLC purity ≥98%, (2) mass spectrometry confirming the expected 4,113.58 g/mol mass, and (3) domestic Canadian shipping to avoid customs holds on international incretin peptide shipments.

Comparisons

• Semaglutide vs retatrutide — single- versus triple-agonist trade-offs.
• Semaglutide vs tirzepatide — GLP-1 alone versus GLP-1 / GIP dual.

Storage

Store lyophilised semaglutide at −20°C for long-term storage. Reconstituted peptide is stable refrigerated at 2–8°C for approximately 4 weeks. Avoid repeated freeze-thaw cycles. See our reconstitution guide for step-by-step handling.