GLP-1 receptor agonist
Semaglutide
GLP-1 receptor mono-agonist (Novo Nordisk)
Overview
Semaglutide is a long-acting GLP-1 receptor agonist developed by Novo Nordisk. It is the same molecule marketed as Ozempic (once-weekly subcutaneous injection, type 2 diabetes), Wegovy (once-weekly subcutaneous injection, chronic weight management), and Rybelsus (once-daily oral tablet, type 2 diabetes). All three products contain semaglutide; the dose range, indication, and delivery route differ.
The molecule was engineered from native GLP-1 to resist enzymatic degradation and to bind albumin — the modifications that extend its half-life to approximately one week and enable once-weekly subcutaneous dosing.
Mechanistically, semaglutide is a GLP-1 receptor mono-agonist. It has no direct activity on GIP or glucagon receptors, distinguishing it from tirzepatide (dual GLP-1/GIP) and retatrutide (triple GLP-1/GIP/glucagon). It acts on pancreatic beta cells (glucose-dependent insulin release, glucagon suppression), on the gut (slowed gastric emptying), and in appetite-regulating regions of the brain (reduced hunger and food reward).
Quick Facts & Evidence
- Category
- GLP-1 receptor agonist
- Research area
- GLP-1 receptor agonist
- Most studied for
- Type 2 diabetes
- Chronic weight management (obesity)
- Major adverse cardiovascular event (MACE) reduction
- Chronic kidney disease in type 2 diabetes
- Heart failure with preserved ejection fraction (HFpEF) in obesity
- Metabolic-associated steatotic liver disease (MASLD)
- Clinical status
- Established clinical use
- Human evidence
- Strong Human Evidence
- Regulatory status
- Approved in FDA, EMA, MHRA
Strong Human Evidence
Backed by multiple large randomised controlled trials in humans and, where applicable, approval by major regulatory agencies.
Research Protocols
Research Protocol Snapshot
Preparation covered on this page
Freeze-dried injectable research format (compounded RUO)
This page covers the RUO lyophilized semaglutide vial reconstituted with bacteriostatic water for subcutaneous research use, following the standard Healthy Mango preparation convention. The FDA-approved Ozempic and Wegovy pre-filled pens are separate commercial products cited only as scientific evidence (pharmacology, published trials, safety) — they are not the presentation described here.
Semaglutide research values at a glance.
| Item | Example value |
|---|---|
| Vial size | 5 mg (compounded RUO convention) |
| Liquid used to mix | Bacteriostatic water |
| Amount of liquid added | 2.5 mL |
| Final concentration | 2 mg/mL |
| How it's given | Subcutaneous injection |
| Research dose | 0.25 mg (starting) titrated toward a maintenance range up to ~2.4 mg once weekly (as studied in trials) |
| Frequency | Once weekly |
| After mixing | Refrigerate; use within 7–10 days |
Reported Dosing
Published semaglutide trials titrate from 0.25 mg once weekly (starting) toward a maintenance range up to ~2.4 mg once weekly, subcutaneously. It is educational reference, not a recommendation.
The Reported Protocol
| Dose | Frequency | Duration | Notes |
|---|---|---|---|
| 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg | Once weekly, subcutaneous | Continuous; titration typically ~4 weeks per step | Weight-management titration studied in the STEP program |
| 0.25 → 0.5 → 1.0 → 2.0 mg | Once weekly, subcutaneous | Continuous; titration typically ~4 weeks per step | T2D titration studied in the SUSTAIN program |
Why protocols vary
The higher-maintenance titration (up to 2.4 mg) was evaluated in the weight-management STEP program; the T2D SUSTAIN program topped out at 2.0 mg. Both are trial dose ladders, not preparation values.
The compounded RUO lyophilized presentation is a research-supply format only; it is not equivalent to the FDA-approved pens and does not carry their post-marketing surveillance framework. This Snapshot describes the RUO form only.
Preparing the Solution
Turning the freeze-dried powder into a measurable liquid.
Documented preparation
The documented research protocol is based on this preparation concentration.
Freeze-dried powder: 5 mg vial (compounded RUO)
Diluent: 2.5 mL bacteriostatic water
Final concentration: 2 mg/mL
Compounded RUO supply-chain convention; concentration calculated · Developer-authored review
Your vial
Matching preparation
Bacteriostatic water
2.5mL
Resulting concentration
2 mg/mL
Equivalent volume
The reported research amount of 0.25–2.4 mg is contained within
0.125–1.200mL
of the prepared solution now in your vial.
Show calculation
- Documented concentration
- 5 mg ÷ 2.5 mL = 2 mg/mL
- Bacteriostatic water to match the documented concentration
- 5 mg ÷ 2 mg/mL = 2.5 mL
- Equivalent volume at this concentration
- 0.25–2.4 mg ÷ 2 mg/mL = 0.125–1.2 mL
This tool performs arithmetic conversions using the preparation example and reported research amount shown on this page. It does not recommend an amount, route, preparation method, or use.
This tool performs arithmetic conversions using the preparation example and reported research amount shown on this page. It does not recommend an amount, route, preparation method, or use.Sources for these values
- Compounded RUO supply-chain convention; dose range from published semaglutide trialsDeveloper-authored review
This example explains how concentration and volume are calculated for the compounded RUO preparation. It is not a preparation guide, and it does not describe any FDA-approved product.
How It's Given
Method used for this format
Subcutaneous injection, once weekly
Published semaglutide pharmacology (SUSTAIN, STEP, SELECT programs) · Peer-reviewed study
Why this method
Semaglutide is a modified 31-amino-acid GLP-1 analogue with an ~168-hour half-life. The subcutaneous route delivers it into circulation without the gastrointestinal degradation that would break the molecule down.
The once-weekly cadence matches the half-life, giving a steady GLP-1R signal without the daily-dosing schedule that shorter-acting GLP-1 agonists require.
Injection sites reported
- Abdomen (rotate sites)
- Thigh
- Upper arm
- Avoid scarred, bruised, inflamed, or infected skin
Storage
Before mixing
- Refrigerate 2–8 °C
- Protect from light
- Do not freeze
General RUO practice · Research-practitioner guide
After mixing
- Refrigerate 2–8 °C
- Use within 7–10 days (compounded RUO)
- Do not freeze
- Discard if cloudy or discoloured
General RUO practice · Research-practitioner guide
Handling
- Direct diluent slowly down the vial wall
- Gently swirl until dissolved — do not shake
- New sterile needle each draw
- Do not share vials
General RUO practice · Research-practitioner guide
Storage guidance summarises standard RUO peptide handling for the compounded lyophilized presentation. FDA-approved Ozempic and Wegovy pre-filled pens have their own labelled storage windows that apply to those separate products, not to this RUO vial.
Common Cycle
Published semaglutide trials use continuous chronic dosing, not cycled therapy. Discontinuation trials (STEP-4) show substantial weight regain over 48 weeks off drug.
- Cycle Length
- Continuous chronic dosing
- Break Before the Next Cycle
- Not applicable
- What the Research Shows
- SELECT cardiovascular trial extended dosing across multiple years
STEP-4; SELECT; SUSTAIN-6 · Peer-reviewed study
Continuous-use evidence is drawn from published trials of the approved product; extrapolation to compounded RUO material rests on the shared molecular identity, not on shared regulatory oversight.
Compound Overview
Current areas of research
The following are indications and effects for which semaglutide has been studied. Regulatory approval varies by brand and jurisdiction.
- Glycaemic control in adults with type 2 diabetes (Ozempic and Rybelsus, FDA/EMA approved)
- Chronic weight management in adults with obesity or overweight with weight-related comorbidities (Wegovy, FDA/EMA approved)
- Reduction in major adverse cardiovascular events in adults with T2D and established CV disease (Ozempic, per SUSTAIN-6 and FDA label)
- Reduction in major adverse cardiovascular events in adults with overweight/obesity and established CV disease without diabetes (Wegovy, per SELECT and FDA label update, 2024)
- Reduction of chronic kidney disease progression in adults with T2D (Ozempic, per FLOW)
- Improvement in heart-failure symptoms and function in adults with HFpEF and obesity (per STEP-HFpEF — investigational for this specific indication in most jurisdictions)
- Investigational research signals in MASLD and other metabolic conditions
Mechanism of action
Semaglutide is a long-acting GLP-1 receptor agonist developed by Novo Nordisk. It is the same molecule marketed as Ozempic (once-weekly subcutaneous injection, type 2 diabetes), Wegovy (once-weekly subcutaneous injection, chronic weight management), and Rybelsus (once-daily oral tablet, type 2 diabetes). All three products contain semaglutide; the dose range, indication, and delivery route differ.
The molecule was engineered from native GLP-1 to resist enzymatic degradation and to bind albumin — the modifications that extend its half-life to approximately one week and enable once-weekly subcutaneous dosing.
Mechanistically, semaglutide is a GLP-1 receptor mono-agonist. It has no direct activity on GIP or glucagon receptors, distinguishing it from tirzepatide (dual GLP-1/GIP) and retatrutide (triple GLP-1/GIP/glucagon). It acts on pancreatic beta cells (glucose-dependent insulin release, glucagon suppression), on the gut (slowed gastric emptying), and in appetite-regulating regions of the brain (reduced hunger and food reward).
- First GLP-1 receptor agonist with published phase-3 cardiovascular outcomes in overweight/obesity without diabetes (SELECT, 2023)
- Mean body-weight reduction of ~14.9% at 68 weeks in STEP-1 at the 2.4 mg dose
- Also available as an oral tablet (Rybelsus) via an SNAC absorption enhancer — the first oral GLP-1
Human research
Semaglutide has been evaluated across multiple phase-3 programs: SUSTAIN (Ozempic in T2D), STEP (Wegovy in obesity), PIONEER (Rybelsus in T2D), SUSTAIN-6 and SELECT (cardiovascular outcomes), FLOW (renal outcomes in T2D), and STEP-HFpEF (heart failure with preserved ejection fraction and obesity). Together these programs enrolled tens of thousands of participants across multiple jurisdictions.
Evidence level for its approved indications is Level A — established clinical use, backed by multiple large randomised controlled trials and regulatory approvals in the US, EU, UK, and other jurisdictions.
STEP-1
Adults with overweight or obesity, without diabetes. Mean body-weight reduction of ~14.9% at 68 weeks with semaglutide 2.4 mg weekly vs ~2.4% with placebo.
STEP-4
Weight-maintenance trial: participants who lost weight over a 20-week lead-in were randomised to continue semaglutide 2.4 mg or switch to placebo. Continuing group extended weight loss; placebo group regained substantially.
STEP-5
104-week outcomes with semaglutide 2.4 mg in adults with overweight or obesity. Sustained mean weight reduction beyond the 68-week endpoint used in STEP-1.
STEP-8
Head-to-head vs daily liraglutide 3 mg in adults with overweight or obesity without diabetes. Semaglutide 2.4 mg weekly produced greater weight reduction than liraglutide 3 mg daily over 68 weeks.
SUSTAIN-6
Cardiovascular outcomes in adults with T2D and established CV disease or high CV risk. Non-inferiority for MACE achieved and superiority demonstrated over placebo; supported the FDA CV indication for Ozempic.
SELECT
Cardiovascular outcomes in adults with overweight or obesity AND established CV disease WITHOUT diabetes. Semaglutide 2.4 mg reduced MACE relative to placebo; supported the 2024 FDA CV indication for Wegovy.
FLOW
Renal outcomes in adults with T2D and chronic kidney disease. Semaglutide reduced the risk of the primary composite renal endpoint vs placebo.
STEP-HFpEF
Adults with heart failure with preserved ejection fraction and obesity. Semaglutide 2.4 mg improved symptom-related quality of life and body-weight outcomes vs placebo.
PIONEER-3
Oral semaglutide (Rybelsus) vs sitagliptin as add-on to metformin ± sulphonylurea in T2D. Oral semaglutide produced greater HbA1c and body-weight reductions than sitagliptin.
Semaglutide is fully approved for clinical use across multiple indications and brands. The FDA authorised Ozempic (type 2 diabetes) in December 2017 and added a cardiovascular risk-reduction indication in T2D + CVD in 2020 based on SUSTAIN-6. Wegovy (chronic weight management in adults with obesity or overweight with weight-related comorbidities) was authorised in June 2021, and in March 2024 the FDA added a cardiovascular risk-reduction indication in overweight/obesity + established CVD without diabetes based on SELECT. Rybelsus (oral, T2D) was authorised in September 2019.
EMA authorisations followed similar timelines: Ozempic (2018), Wegovy (2022), Rybelsus (2020). MHRA authorisation is in place for all three brands in the United Kingdom.
Beyond these approved indications, semaglutide is being evaluated in ongoing phase-3 trials for MASLD (ESSENCE), further HFpEF populations, chronic kidney disease progression (FLOW readout published in 2024), and Alzheimer's disease (EVOKE). None of these secondary indications are currently approved.
Safety considerations
The following have been reported in the pooled SUSTAIN, STEP, PIONEER, SUSTAIN-6, and SELECT data and in prescribing information. Frequencies vary by dose; higher doses show higher incidence.
- Nausea — Most common; usually transient; peak during titration
- Vomiting
- Diarrhoea
- Constipation
- Reduced appetite and early satiety
- Injection-site reactions — Mild, localised (SC brands)
- Hypoglycaemia — Primarily when combined with insulin or sulphonylureas
- Cholelithiasis (gallstones) — Reported at higher incidence than placebo
- Acute pancreatitis — Rare; monitor for symptoms
- Diabetic retinopathy complications — Increased incidence reported in SUSTAIN-6 in participants with pre-existing severe retinopathy — screen and monitor per label
- Rybelsus-specific: taste disturbance and reduced appetite noted with the oral formulation
The contraindications below are drawn directly from the FDA and EMA labelling for Ozempic, Wegovy, and Rybelsus. Any decision about suitability should involve a qualified clinician with access to the individual's medical history. The dominant safety signal in trials is dose-dependent gastrointestinal effects during titration; rare but serious events include acute pancreatitis, gallbladder disease, acute kidney injury (secondary to dehydration from persistent vomiting or diarrhoea), and severe hypersensitivity. A boxed-style warning appears in all three labels regarding thyroid C-cell tumours based on rodent studies.
- Personal or family history of medullary thyroid carcinoma (MTC)
- Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
- Known serious hypersensitivity to semaglutide or any excipient
- Pregnancy (per label; effective contraception recommended in individuals of reproductive potential)
- Breastfeeding — data are limited
Monitoring
- HbA1c and fasting glucose (diabetes)
- Weight and body composition
- Renal function during illness or dehydration
- Signs and symptoms of pancreatitis (severe abdominal pain radiating to the back)
- Diabetic retinopathy screening in participants with pre-existing DR
- Vitamin and micronutrient status where intake is markedly reduced by appetite suppression
Frequently asked questions
How does semaglutide compare to tirzepatide?
SURPASS-2 (2021) was the head-to-head trial in type 2 diabetes: at every tested tirzepatide dose (5, 10, 15 mg), tirzepatide produced a greater HbA1c reduction and greater weight loss than semaglutide 1 mg over 40 weeks. In obesity populations no adequately-powered head-to-head trial vs. semaglutide 2.4 mg has been published; cross-trial comparisons of STEP-1 (~14.9% at 68 weeks) and SURMOUNT-1 (~20.9% at 72 weeks) consistently show larger mean weight reductions with tirzepatide, but cross-trial comparisons cannot substitute for a direct randomised comparison. Cardiovascular outcomes data exists for semaglutide (SUSTAIN-6, SELECT) but not yet for tirzepatide (SURPASS-CVOT is ongoing).
Is Rybelsus the same drug as Ozempic?
Yes — both are semaglutide. Rybelsus is an oral tablet formulated with the absorption enhancer SNAC (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate). It must be taken on an empty stomach with ≤120 mL of plain water and no other medications for 30 minutes. Bioavailability is low relative to subcutaneous injection, and it is approved for type 2 diabetes only — not for chronic weight management.
Is the weight loss maintained long-term?
STEP-4 randomised participants who had lost weight on semaglutide 2.4 mg during a 20-week lead-in to either continue the drug or switch to placebo. The continuing group extended their loss over the following 48 weeks; the placebo group regained a substantial fraction. STEP-5 extended the endpoint to 104 weeks, with sustained mean weight reduction. Weight loss appears to be contingent on continued treatment.
What is the difference between Ozempic and Wegovy?
They contain the same molecule, semaglutide, but at different maintenance doses and for different regulatory indications. Ozempic maintenance doses are 0.5, 1, or 2 mg weekly (type 2 diabetes; SUSTAIN program). Wegovy maintenance dose is 2.4 mg weekly (chronic weight management; STEP program). Pens and titration schedules differ; the active drug is the same molecule.
Why does the label emphasise titration so heavily?
Gastrointestinal side effects (nausea, vomiting, diarrhoea) are dose-dependent and are the leading reason for discontinuation. The four-week titration schedule allows the body to adapt at each step, dramatically reducing the intensity of GI effects compared with starting at a therapeutic dose.
What does the SELECT trial mean in practice?
SELECT (2023) enrolled adults with overweight or obesity AND established cardiovascular disease but WITHOUT diabetes. Semaglutide 2.4 mg reduced major adverse cardiovascular events relative to placebo. In March 2024 the FDA updated the Wegovy label to include a cardiovascular risk-reduction indication for this population — the first time a GLP-1 was approved for CV risk reduction in overweight/obesity without diabetes.
References
- [1]
Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) — Wilding JPH, Batterham RL, Calanna S, et al., New England Journal of Medicine (2021)
- [2]
Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity: The STEP 4 Randomized Clinical Trial — Rubino D, Abrahamsson N, Davies M, et al., JAMA (2021)
- [3]
Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial — Garvey WT, Batterham RL, Bhatta M, et al., Nature Medicine (2022)
- [4]
Effect of Weekly Subcutaneous Semaglutide vs Daily Liraglutide on Body Weight in Adults With Overweight or Obesity Without Diabetes: The STEP 8 Randomized Clinical Trial — Rubino DM, Greenway FL, Khalid U, et al., JAMA (2022)
- [5]
Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (SUSTAIN-6) — Marso SP, Bain SC, Consoli A, et al., New England Journal of Medicine (2016)
- [6]
Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT) — Lincoff AM, Brown-Frandsen K, Colhoun HM, et al., New England Journal of Medicine (2023)
- [7]
Effect of Additional Oral Semaglutide vs Sitagliptin on Glycated Hemoglobin in Adults With Type 2 Diabetes Uncontrolled With Metformin Alone or With Sulfonylurea: The PIONEER 3 Randomized Clinical Trial — Rosenstock J, Allison D, Birkenfeld AL, et al., JAMA (2019)
- [8]
Semaglutide in Patients with Heart Failure with Preserved Ejection Fraction and Obesity (STEP-HFpEF) — Kosiborod MN, Abildstrøm SZ, Borlaug BA, et al., New England Journal of Medicine (2023)
- [9]
Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (FLOW) — Perkovic V, Tuttle KR, Rossing P, et al., New England Journal of Medicine (2024)
- [10]
FDA Prescribing Information — OZEMPIC (semaglutide) injection — U.S. Food and Drug Administration (2017)
https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/209637lbl.pdf
- [11]
FDA Prescribing Information — WEGOVY (semaglutide) injection — U.S. Food and Drug Administration (2021)
https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/215256s000lbl.pdf
- [12]
FDA Prescribing Information — RYBELSUS (semaglutide) tablets — U.S. Food and Drug Administration (2019)
https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/213051s000lbl.pdf
- [13]
Ozempic (semaglutide) — European Public Assessment Report (EPAR) — European Medicines Agency (2018)
- [14]
Wegovy (semaglutide) — European Public Assessment Report (EPAR) — European Medicines Agency (2022)
- [15]
Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide — Lau J, Bloch P, Schäffer L, et al., Journal of Medicinal Chemistry (2015)
- [16]
Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2) — Frías JP, Davies MJ, Rosenstock J, et al., New England Journal of Medicine (2021)
Laboratory Reference Notice
This section summarizes procedures and study parameters reported in published scientific literature and laboratory protocols. It is provided for educational and research reference only and must not be interpreted as medical advice, clinical guidance, or instructions for personal use.
Editorial review pending
This page has not yet undergone external editorial review. Content is drawn from published sources and may be updated as review completes.
Related
Related topics
Related on Healthy Mango
Guides
- Understanding evidence levels
- Understanding GLP-1 research
- Understanding GIP biology
- Understanding glucagon biology
- Understanding peptide half-life
- Bioavailability explained
- How to read a clinical trial
- Why some peptides become medicines
- Lyophilized vs liquid preparations
- Storage and cold chain best practices
Categories