Catalog
GLP-1 receptor agonist

Semaglutide

aka Ozempic · Wegovy · Rybelsus

Weekly GLP-1 RA — pivotal A-grade evidence in T2D, obesity, and CVD risk reduction.

FDA-approvedGrade A — Clinically established
Target
GLP-1R (Gs-coupled GPCR)
Sequence / engineering
31 aa, lipidated (C18 fatty diacid) for albumin binding → ~7-day half-life.

Mechanism of action

Selective GLP-1R agonist. Stimulates glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite via central GLP-1R signaling in hypothalamic and brainstem nuclei.

Pharmacokinetics

Subcutaneous (Ozempic/Wegovy) or oral with SNAC absorption enhancer (Rybelsus). t½ ≈ 165 h. Steady-state ~4–5 weeks. Renal/hepatic clearance minimal — proteolysis dominates.

Clinical context

T2D (Ozempic/Rybelsus); chronic weight management with BMI ≥30 or ≥27+comorbidity (Wegovy); MACE risk reduction in adults with established CVD and overweight/obesity (SELECT, 2023).

Dosing
Wegovy: 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg SC weekly (4-week steps). Ozempic: 0.25 → 0.5 → 1.0 → 2.0 mg weekly. Slow titration reduces GI AEs.

Monitoring

  • HbA1c, fasting glucose
  • Weight, blood pressure
  • Pancreatitis symptoms (lipase if suspected)
  • Gallbladder symptoms
  • Pregnancy status (discontinue ≥2 mo before conception)

Safety

Black-box warning
Risk of thyroid C-cell tumors (rodent data); contraindicated with MTC or MEN-2.
Contraindications
  • Personal/family hx of medullary thyroid carcinoma
  • MEN-2
  • Prior serious hypersensitivity
Adverse effects
  • Nausea/vomiting/constipation (dose-related, usually titration)
  • Pancreatitis (rare)
  • Cholelithiasis
  • Gastroparesis exacerbation
  • Diabetic retinopathy progression in poorly controlled T2D

Myth vs reality

CLAIMCompounded semaglutide is the same molecule.
REALITYOften supplied as semaglutide sodium/acetate salts — different molecules with no FDA-approved equivalent and documented dosing errors.
CLAIMGLP-1 RAs cause permanent gastroparesis.
REALITYDelayed gastric emptying is a mechanism, not a complication; symptoms typically resolve on discontinuation.

Patient counseling points

  • Inject same day each week, any time of day, with or without food.
  • Eat smaller meals; stop when full to avoid nausea.
  • Hold dose 1 week before any procedure requiring sedation (gastric retention risk).
  • Effective contraception during therapy and for 2 months before conception.

Relevant labs

Hemoglobin A1cLipaseALT / AST

Covered in modules

Module 03
GLP-1 Receptor Agonists
Semaglutide, liraglutide, dulaglutide, exenatide — the class that rewrote metabolic medicine.
Module 14
Safety, Regulation & Compounded Peptides
503A vs 503B vs research-only — what the FDA actually says.

Key references

Related compounds

Dual GIP / GLP-1 receptor agonist
Tirzepatide
GLP-1 receptor agonist (daily)
Liraglutide
Selective GH secretagogue (GHS-R agonist)
Ipamorelin
Long-acting GHRH analog
CJC-1295 (with/without DAC)

Generate prescriber-grade deep dive

Pull in expanded mechanism, PK/PD, dosing strategies for special populations, drug interactions, monitoring cadence, head-to-head differentials, prescriber pearls, and patient FAQs for Semaglutide.

Educational reference. Not medical advice. Always verify against current FDA labeling and local regulatory guidance before prescribing or counseling.