Semaglutide is a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist developed by Novo Nordisk. It is a 31-amino acid peptide analog of human GLP-1(7-37) with two key modifications: an amino acid substitution at position 8 (Ala8Aib) that confers resistance to dipeptidyl peptidase-4 (DPP-4) degradation, and a C18 fatty diacid chain attached via a linker at position 26 that enables albumin binding. Together, these modifications extend the half-life to approximately 7 days, allowing once-weekly subcutaneous injection.
Semaglutide represents the benchmark for what evidence-based peptide medicine looks like. Its development includes one of the most comprehensive clinical trial programs in obesity pharmacotherapy history: the global STEP (Semaglutide Treatment Effect in People with obesity) program, comprising over a dozen randomized controlled trials enrolling tens of thousands of participants. The compound has achieved FDA approval across multiple formulations and indications.
Approved formulations include: Ozempic (semaglutide 0.5 mg, 1.0 mg, 2.0 mg SC weekly) for type 2 diabetes; Wegovy (semaglutide 2.4 mg SC weekly) for chronic weight management and cardiovascular risk reduction; and Rybelsus (semaglutide 3 mg, 7 mg, 14 mg oral daily) for type 2 diabetes. In March 2024, Wegovy received an expanded FDA indication for cardiovascular risk reduction in adults with established heart disease and overweight or obesity.
A long-acting GLP-1 receptor agonist approved for type 2 diabetes and for chronic weight management. Research material is supplied as a lyophilised powder that is reconstituted with bacteriostatic water before measurement; the approved products are not.
| Weeks | Dosage | Syringe units (U-100) |
|---|---|---|
| Weeks 1–4 | 0.25 mg | 5 units0.05 mL |
| Weeks 5–8 | 0.5 mg | 10 units0.1 mL |
| Weeks 9–12 | 1 mg | 20 units0.2 mL |
| Weeks 13–16 | 1.7 mg | 34 units0.34 mL |
| Week 17+ | 2.4 mg | 48 units0.48 mL |
| Weeks | Dosage | Syringe units (U-100) |
|---|---|---|
| Weeks 1–4 | 0.25 mg | 3.75 units0.04 mL |
| Weeks 5–8 | 0.5 mg | 7.5 units0.07 mL |
| Weeks 9–12 | 1 mg | 15 units0.15 mL |
| Weeks 13–16 | 1.7 mg | 25.5 units0.26 mL |
| Week 17+ | 2.4 mg | 36 units0.36 mL |
FrequencyOnce weekly, subcutaneous.
Every row is the titration schedule set out in the Wegovy prescribing information for chronic weight management, not a figure extrapolated from a trial — the four lower steps exist to limit gastrointestinal effects and are starter amounts rather than maintenance ones. Approved semaglutide is supplied as a pre-filled pen at a fixed concentration, so the syringe units worked out from it describe only lyophilised research material reconstituted exactly as shown above and will not correspond to any marking on a pen. The 10 mg vial comes to 5 mg/mL and the 20 mg vial, made up with 3 mL, to about 6.67 mg/mL, so the units differ between the two charts; a 10 mg vial holds four 2.4 mg maintenance amounts and a 20 mg vial holds eight. From the 10 mg vial the 0.25 mg starting step is a 5-unit draw, close to the smallest volume a 50-unit syringe measures reliably, and the 2.4 mg step is 48 units — inside one syringe, but with almost nothing to spare. From the 20 mg vial the same two steps are about 3.75 and 36 units, which leaves more room at the top of the schedule and less at the bottom.
What this evidence establishes. Semaglutide is FDA-approved and its dosing is set by a prescribing label rather than inferred from a trial, which makes it the best-documented compound on this site. The schedule is a titration: the four lower steps exist to manage gastrointestinal tolerability and are not intended as maintenance doses. Approved products are supplied as pre-filled pens at fixed concentrations, so the reconstitution arithmetic shown above applies only to lyophilised research material and not to any approved product.
Sources: Wegovy (semaglutide 2.4 mg) FDA prescribing information · Ozempic (semaglutide) FDA prescribing information · SELECT trial, 2023 — cardiovascular outcomes
For educational and laboratory research purposes only. It does not provide medical advice, dosing recommendations, or instructions for human or veterinary use. Syringe units assume a U-100 syringe, on which 1 mL is 100 units and a 50-unit syringe holds 0.5 mL.
Semaglutide binds to and activates the GLP-1 receptor, a G protein-coupled receptor (GPCR) expressed in the pancreas, brain, gastrointestinal tract, heart, and kidneys. Its mechanisms span multiple organ systems:
Activates GLP-1 receptors in the hypothalamus and brainstem (NTS, area postrema) to reduce hunger, increase satiety, and decrease food intake
Slows gastric emptying rate, prolonging postprandial satiety and reducing glycemic excursions after meals
Enhances glucose-dependent insulin secretion from pancreatic beta cells while suppressing inappropriate glucagon release
Reduces systemic inflammation, improves endothelial function, and decreases atherosclerotic burden (SELECT trial)
Alters neural responses to food cues in brain reward circuits, reducing preference for high-fat and energy-dense foods
Produces sustained negative energy balance through reduced caloric intake (~30-40% reduction) rather than increased expenditure
Pharmacokinetic advantage: The C18 fatty diacid modification enables non-covalent albumin binding, which serves three functions: protection from DPP-4 degradation, reduced renal clearance, and a depot effect creating sustained receptor activation. This is why semaglutide achieves once-weekly dosing where native GLP-1 has a half-life of approximately 2 minutes.
Semaglutide requires a structured dose-escalation protocol to minimize gastrointestinal side effects. The standard Wegovy titration for chronic weight management is as follows:
| Weeks | Dose | Purpose |
|---|---|---|
| Weeks 1-4 | 0.25 mg SC weekly | Initial tolerability assessment |
| Weeks 5-8 | 0.5 mg SC weekly | First dose escalation |
| Weeks 9-12 | 1.0 mg SC weekly | Second dose escalation |
| Weeks 13-16 | 1.7 mg SC weekly | Third dose escalation |
| Week 17+ | 2.4 mg SC weekly | Therapeutic maintenance dose |
The investigational 7.2 mg dose (STEP UP program, 2025) uses an extended titration over 28 weeks, escalating from 0.25 mg through intermediate doses of 3.6 mg and 5.0 mg before reaching the 7.2 mg target. This higher dose achieved 20.7% mean weight loss at 72 weeks, with approximately one-third of participants achieving 25% or greater weight loss.
Unlike many compounds profiled on this site, semaglutide has extensive human safety data from large randomized controlled trials. The following contraindications and warnings are derived from the FDA-approved prescribing information and published clinical data:
| Condition / Factor | Risk Level | Rationale |
|---|---|---|
| Personal/family history of medullary thyroid carcinoma (MTC) | CONTRAINDICATED | Black box warning. GLP-1 RAs cause thyroid C-cell tumors in rodents. Contraindicated in MTC or MEN2 syndrome. |
| History of pancreatitis | HIGH | Cases of acute pancreatitis reported in clinical trials. Discontinue promptly if pancreatitis is suspected. |
| Severe gastrointestinal disease | HIGH | Gastroparesis, inflammatory bowel disease, or bowel obstruction may be worsened by delayed gastric emptying. |
| Diabetic retinopathy complications | MODERATE | Rapid glycemic improvement may temporarily worsen diabetic retinopathy. Monitoring recommended in diabetes patients. |
| Gallbladder disease | MODERATE | Cholelithiasis and cholecystitis reported at higher rates with semaglutide. Risk increases with rapid weight loss. |
| Renal impairment | MODERATE | Dehydration from GI side effects can worsen renal function. Use caution in patients with renal disease. |
| Pregnancy / breastfeeding | CONTRAINDICATED | Discontinue at least 2 months before planned conception. Animal studies show embryofetal toxicity. |
| Concurrent insulin or sulfonylurea use | MODERATE | Increased hypoglycemia risk. Dose reduction of insulin or sulfonylurea may be needed. |
| Suicidal ideation (under investigation) | LOW (monitoring) | Post-marketing reports being evaluated by FDA/EMA. Large clinical trials have not confirmed a causal signal. |
| General safety profile | WELL-CHARACTERIZED | Most common adverse events are GI (nausea, vomiting, diarrhea, constipation). Mostly mild-to-moderate and resolve during titration. |
FDA: Semaglutide holds multiple FDA approvals: Ozempic (2017) for type 2 diabetes; Rybelsus (2019) for oral type 2 diabetes treatment; and Wegovy (2021) for chronic weight management. In 2024, Wegovy's indication was expanded to include cardiovascular risk reduction in adults with established heart disease and overweight/obesity.
EMA: Approved across the European Union under the same brand names. Widely available across global markets.
WADA: GLP-1 receptor agonists are not prohibited by the World Anti-Doping Agency.
Key distinction: Semaglutide is what evidence-based peptide medicine looks like. It has an enormous clinical trial database, well-characterized safety profile, FDA approval across multiple indications, established manufacturing standards, and real-world post-marketing surveillance. When evaluating any other peptide compound, the standard of evidence that semaglutide provides should serve as the benchmark for comparison.
Test your understanding of semaglutide's evidence base, mechanism, and clinical considerations.
This profile is for educational and research purposes only. It is not medical advice, and nothing on it is a protocol, a recommendation, or an instruction for use in a person or an animal.
Athena Peptides Education does not prescribe, sell, or recommend any compound. Compounds discussed here are for laboratory research only and are not for human consumption. Always consult a qualified physician before making any decision about your health.