Subcutaneous Semaglutide (Ozempic / Wegovy)
semaglutide injection, once-weekly subcutaneous administration
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| T2DM — glycemic control (Ozempic) | Adults | Adjunct to diet/exercise; mono or combo | FDA Approved |
| CV risk reduction in T2DM — reduce MACE in established CVD (Ozempic) | Adults with T2DM + established CVD | Adjunct to standard of care | FDA Approved |
| Renal outcomes in T2DM + CKD — reduce sustained eGFR decline, ESKD, CV death (Ozempic) | Adults with T2DM + CKD | Adjunct to standard of care | FDA Approved (Jan 2025) |
| Chronic weight management (Wegovy) | Adults with BMI ≥30, or ≥27 with weight-related comorbidity | Adjunct to reduced-calorie diet and exercise | FDA Approved |
| CV risk reduction in overweight/obesity — reduce MACE with established CVD (Wegovy) | Adults with CVD + BMI ≥27 (without diabetes) | Adjunct to diet/exercise + standard of care | FDA Approved (Mar 2024) |
Subcutaneous semaglutide is the most broadly indicated GLP-1 receptor agonist, available as Ozempic (for type 2 diabetes and its cardiovascular and renal complications) and Wegovy (for chronic weight management and cardiovascular risk reduction in overweight/obesity). The January 2025 Ozempic label expansion added the CKD/renal outcomes indication based on the FLOW trial, establishing semaglutide as the first GLP-1 RA approved for kidney disease outcomes. Ozempic is not approved for weight management, and Wegovy is not approved for glycemic control — each brand carries distinct indications despite containing the same active molecule.
Ozempic for weight loss without diabetes: Frequently prescribed off-label for weight management when Wegovy is unavailable or not covered by insurance. The same molecule at a lower maximum dose (2 mg vs 2.4 mg weekly). Evidence quality: High (STEP trials established efficacy at 2.4 mg; Ozempic max 2 mg provides meaningful but modestly lower weight reduction).
Non-alcoholic steatohepatitis (NASH/MASH): Semaglutide 2.4 mg weekly demonstrated histological resolution of steatohepatitis without worsening fibrosis in phase 2 studies. Dedicated phase 3 trials are ongoing. Evidence quality: Moderate (phase 2 RCT positive; phase 3 pending).
Dosing
Ozempic — Type 2 Diabetes and Cardiorenal Indications
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| T2DM — glycemic control (new start) | 0.25 mg weekly × 4 wk | 0.5 mg weekly | 2 mg weekly | 0.25 mg is initiation only — not therapeutic Escalate: 0.5 → 1 → 2 mg, each step ≥4 weeks apart |
| T2DM — add-on to metformin, SU, or insulin | 0.25 mg weekly × 4 wk | 0.5–2 mg weekly | 2 mg weekly | Consider reducing SU or insulin dose to lower hypoglycemia risk Same titration schedule regardless of background therapy |
| T2DM + established CVD — MACE reduction | 0.25 mg weekly × 4 wk | 0.5–1 mg weekly | 2 mg weekly | SUSTAIN-6 used 0.5 and 1 mg doses; 26% MACE reduction Both 0.5 and 1 mg contributed to CV benefit |
| T2DM + CKD — renal outcomes | 0.25 mg weekly × 4 wk | 1 mg weekly | 1 mg weekly | FLOW trial maintenance dose was 1 mg; 24% reduction in renal composite Target 1 mg as per PI for this specific indication |
Wegovy — Chronic Weight Management
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Chronic weight management (BMI ≥30 or ≥27 + comorbidity) | 0.25 mg weekly × 4 wk | 2.4 mg weekly | 2.4 mg weekly | 16-week escalation: 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg Each escalation step is 4 weeks; target 2.4 mg maintenance |
| CV risk reduction in overweight/obesity + CVD (no diabetes) | 0.25 mg weekly × 4 wk | 2.4 mg weekly | 2.4 mg weekly | SELECT trial: 20% MACE reduction at 2.4 mg Same escalation schedule as weight management |
Unlike oral semaglutide, the subcutaneous injection can be administered at any time of day, with or without meals, in the abdomen, thigh, or upper arm. The injection day can be changed as long as there are at least 2 days (48 hours) between doses. If a dose is missed, it should be given within 5 days; if more than 5 days have passed, skip and resume the regular schedule. Never share pens between patients, even with a needle change — this is a blood-borne pathogen transmission risk.
Pharmacology
Mechanism of Action
Semaglutide is a long-acting GLP-1 analog with 94% structural homology to native human GLP-1. Three critical structural modifications distinguish it from the endogenous hormone: an amino acid substitution at position 8 (Aib) confers resistance to dipeptidyl peptidase-4 (DPP-4) degradation, while a C18 fatty di-acid chain attached at position 26 via a hydrophilic linker enables strong non-covalent albumin binding — the primary mechanism responsible for the ~1-week half-life that permits once-weekly dosing. Semaglutide activates GLP-1 receptors on pancreatic beta cells to stimulate glucose-dependent insulin secretion and suppress glucagon release from alpha cells. Beyond glycemic effects, it delays gastric emptying, reduces appetite and food intake through central satiety pathways, and produces sustained weight loss. Cardiorenal benefits include reductions in systemic inflammation, improved endothelial function, and renoprotective effects that appear partially independent of glycemic improvement.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | SC bioavailability ~89%; Tmax 1–3 days post-injection; dose-proportional exposure across 0.5–2 mg range | Predictable absorption allows once-weekly dosing at any time of day, with or without food |
| Distribution | Apparent Vd ~12.5 L; >99% albumin-bound; primarily vascular compartment | Albumin binding is the major protraction mechanism enabling the ~1-week half-life; binding unaffected by renal or hepatic impairment |
| Metabolism | Proteolytic cleavage of peptide backbone + sequential beta-oxidation of C18 fatty di-acid side chain; not organ-specific; no CYP450 involvement | No dose adjustment needed for renal impairment (including ESKD) or hepatic impairment; negligible CYP-mediated drug interaction potential |
| Elimination | t½ ~1 week (~165 h); clearance ~0.05 L/h; excretion via urine (~3% intact) and feces; present in circulation ~5 weeks after last dose | Requires ≥2-month washout before planned pregnancy; steady state in 4–5 weeks of weekly dosing |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Nausea | 15.8% (0.5 mg); 20.3% (1 mg) | Dose-related (vs 6.1% placebo); most common during dose escalation; typically improves over 4–8 weeks |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Diarrhea | 8.5% (0.5 mg); 8.8% (1 mg) | Versus 1.9% placebo; can contribute to dehydration and AKI if severe |
| Vomiting | 5.0% (0.5 mg); 9.2% (1 mg) | Versus 2.3% placebo; primarily during dose escalation |
| Abdominal pain | 7.3% (0.5 mg); 5.7% (1 mg) | Versus 4.6% placebo; differentiate from pancreatitis symptoms |
| Constipation | 5.0% (0.5 mg); 3.1% (1 mg) | Versus 1.5% placebo; related to delayed gastric emptying |
| Dyspepsia, eructation, flatulence, GERD | 0.4–3.5% each | Additional GI effects less common; generally mild |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Acute pancreatitis | 0.3 events/100 pt-years | Any time; includes hemorrhagic/necrotizing forms | Discontinue immediately; hospitalize; fatal cases reported postmarketing |
| Diabetic retinopathy complications | 3.0% vs 1.8% placebo | Early treatment; associated with rapid HbA1c improvement | Monitor patients with baseline retinopathy; SUSTAIN-6: HR 1.76 (1.11–2.78) |
| Cholelithiasis / cholecystitis | 0.4–1.5% | Months into therapy; GLP-1 class effect | Gallbladder imaging if symptoms develop; surgical referral as indicated |
| Acute kidney injury | Rare (postmarketing) | Often during escalation with GI-related dehydration | Rehydrate; monitor renal function; some cases required hemodialysis |
| Anaphylaxis / angioedema | Very rare (postmarketing) | Any time | Discontinue permanently; emergency management |
| Pulmonary aspiration (peri-procedural) | Rare (postmarketing) | During general anesthesia/deep sedation | Inform anesthesia team; GLP-1 class-wide warning (Jan 2025 label update) |
The 4-week 0.25 mg initiation dose exists solely to improve GI tolerability. Most nausea and vomiting are transient and occur during dose escalation. Advise patients to eat smaller, lighter meals, avoid high-fat foods, and maintain hydration. If GI effects persist at a given dose, delay further escalation by an additional 4 weeks. The 2 mg Ozempic dose and 2.4 mg Wegovy dose carry higher GI rates than 0.5–1 mg. Monitor renal function during significant GI symptoms, as dehydration-related AKI has been reported.
Amylase: Mean 13% increase. Lipase: Mean 22% increase. These elevations are expected with GLP-1 agonists and do not, by themselves, indicate pancreatitis. Heart rate: Mean increase of 2–3 bpm (vs 0.3 bpm decrease with placebo). Injection site reactions: Reported in 0.2% of patients.
Drug Interactions
Subcutaneous semaglutide has a low drug interaction profile. It is not metabolized by CYP450 enzymes and does not inhibit or induce major CYP isoforms. It delays gastric emptying, which can theoretically alter absorption of co-administered oral medications, but clinical pharmacology studies showed no clinically relevant impact on absorption of commonly used oral drugs. The primary interaction concern is pharmacodynamic — additive hypoglycemia risk when combined with insulin or secretagogues.
Monitoring
- HbA1cBaseline, then every 3–6 months
RoutinePrimary efficacy marker for Ozempic. Expected HbA1c reductions: 1.0–1.4% at 0.5 mg, 1.4–1.8% at 1 mg. Escalate dose if target not met after ≥4 weeks at current dose. - Body WeightEach visit
RoutinePrimary efficacy marker for Wegovy. STEP-1 showed mean 14.9% weight loss at 2.4 mg (vs 2.4% placebo). Also important secondary endpoint for Ozempic. - Renal FunctionBaseline; during GI symptoms
Trigger-basedMonitor eGFR/creatinine if nausea, vomiting, or diarrhea causes dehydration. AKI cases reported postmarketing. For CKD indication, monitor eGFR per standard CKD guidelines. - Diabetic RetinopathyBaseline; per guidelines
RoutineSUSTAIN-6 showed increased retinopathy complications (3.0% vs 1.8%); risk higher with baseline retinopathy (8.2% vs 5.2%). Monitor closely during rapid glycemic improvement. - Blood GlucoseIncreased frequency with insulin/SU
Trigger-basedSevere hypoglycemia 0–1.5% as monotherapy; up to 1.2% with concomitant SU. Monitor more frequently during initiation and dose escalation when combined with hypoglycemia-causing agents. - Pancreatitis SignsOngoing clinical vigilance
Trigger-basedEducate patients on symptoms. Amylase +13% and lipase +22% elevations are expected and not diagnostic of pancreatitis. 0.3 events/100 patient-years in glycemic control trials. - ThyroidClinical assessment only
Trigger-basedRoutine calcitonin or thyroid ultrasound not recommended (low specificity). Evaluate neck mass, dysphagia, persistent hoarseness. Calcitonin >50 ng/L may indicate MTC. - GallbladderIf symptoms develop
Trigger-basedCholelithiasis reported in up to 1.5% (0.5 mg). Evaluate with imaging if right upper quadrant pain, especially in patients with rapid weight loss.
Contraindications & Cautions
Absolute Contraindications
- Personal or family history of medullary thyroid carcinoma (MTC)
- Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
- Prior serious hypersensitivity to semaglutide or any excipient — anaphylaxis and angioedema reported
Relative Contraindications (Specialist Input Recommended)
- History of pancreatitis — GLP-1 agonists associated with acute pancreatitis; avoid in active pancreatic disease
- Severe gastroparesis — semaglutide further delays gastric emptying; not recommended
- Pregnancy or planned pregnancy within 2 months — embryofetal toxicity at sub-therapeutic exposures in animals; long washout required
- History of serious hypersensitivity to another GLP-1 RA — cross-reactivity unknown
Use with Caution
- Pre-existing diabetic retinopathy — SUSTAIN-6 showed increased complications (HR 1.76); particularly proliferative retinopathy or macular edema
- Concomitant insulin or sulfonylureas — proactively reduce dose to mitigate hypoglycemia
- Planned surgery requiring general anesthesia — inform anesthesia team; risk of retained gastric contents and pulmonary aspiration
- GI symptoms with renal impairment — nausea/vomiting can precipitate volume depletion and AKI
Semaglutide caused dose-dependent and treatment-duration-dependent thyroid C-cell tumors in rodents at clinically relevant exposures. Whether semaglutide causes thyroid C-cell tumors including MTC in humans has not been determined. Ozempic and Wegovy are contraindicated in patients with personal or family history of MTC or MEN 2. Counsel all patients on symptoms of thyroid tumors. Routine calcitonin screening is not recommended due to low diagnostic specificity.
Patient Counselling
Purpose of Therapy
Semaglutide injection works by mimicking a natural gut hormone (GLP-1) that helps the body release insulin when blood sugar is high, reduces appetite, and slows digestion. Ozempic is used once weekly by injection to improve blood sugar, protect the heart and kidneys in type 2 diabetes. Wegovy is used at a higher dose for long-term weight management.
How to Use
Inject once a week, on the same day each week, at any time of day, with or without meals. Rotate injection sites between the abdomen, thigh, and upper arm. Store unused pens in the refrigerator; once in use, a pen can be kept at room temperature (up to 86 degrees F) for up to 56 days. Never share pens with anyone else.
Sources
- Ozempic (semaglutide) injection, for subcutaneous use. Full Prescribing Information. Revised January 2025. Novo Nordisk Inc. FDA LabelPrimary source for Ozempic dosing, adverse reactions (Table 1), contraindications, PK data, and all three indications including the Jan 2025 CKD/renal label expansion.
- Wegovy (semaglutide) injection, for subcutaneous use. Full Prescribing Information. Novo Nordisk Inc. FDA LabelSource for Wegovy-specific dosing escalation (up to 2.4 mg), weight management indication, and Mar 2024 CV risk reduction indication.
- Marso SP, Bain SC, Consoli A, et al. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes. N Engl J Med. 2016;375(19):1834–1844. doi:10.1056/NEJMoa1607141SUSTAIN-6 (N=3,297): 26% MACE reduction (HR 0.74; 95% CI 0.58–0.95); 39% nonfatal stroke reduction; basis for Ozempic CV indication.
- Perkovic V, Tuttle KR, Rossing P, et al. Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes. N Engl J Med. 2024;391(2):109–121. doi:10.1056/NEJMoa2403347FLOW trial (N=3,533): 24% reduction in kidney composite endpoint; stopped early for efficacy; basis for Ozempic Jan 2025 CKD indication.
- Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes. N Engl J Med. 2023;389(24):2221–2232. doi:10.1056/NEJMoa2307563SELECT trial (N=17,604): 20% MACE reduction (HR 0.80; 95% CI 0.72–0.90) in overweight/obese patients with CVD but without diabetes; basis for Wegovy CV indication.
- Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989–1002. doi:10.1056/NEJMoa2032183STEP-1 (N=1,961): 14.9% mean weight loss with semaglutide 2.4 mg vs 2.4% placebo at 68 weeks; pivotal Wegovy weight management trial.
- Ahren B, Masmiquel L, Kumar H, et al. Efficacy and safety of once-weekly semaglutide versus once-daily sitagliptin as add-on to metformin, thiazolidinediones, or both, in patients with type 2 diabetes (SUSTAIN 2). Lancet Diabetes Endocrinol. 2017;5(5):341–354. doi:10.1016/S2213-8587(17)30092-XHead-to-head superiority vs sitagliptin; HbA1c reductions of 1.3% (0.5 mg) and 1.6% (1 mg) vs 0.5% with sitagliptin at 56 weeks.
- American Diabetes Association Professional Practice Committee. Standards of Care in Diabetes — 2025. Diabetes Care. 2025;48(Suppl 1). doi:10.2337/dc25-SINTRecommends GLP-1 RA with proven CV benefit as preferred agent in T2DM + ASCVD, HF, or CKD; semaglutide qualifies based on SUSTAIN-6, FLOW, and SOUL.
- Marx N, Federici M, Schutt K, et al. 2023 ESC Guidelines for the management of cardiovascular disease in patients with diabetes. Eur Heart J. 2023;44(39):4043–4140. doi:10.1093/eurheartj/ehad192European guideline positioning GLP-1 RAs as first-line cardiometabolic therapy alongside SGLT2 inhibitors for T2DM with CVD.
- Nauck MA, Quast DR, Wefers J, Meier JJ. GLP-1 receptor agonists in the treatment of type 2 diabetes — state-of-the-art. Mol Metab. 2021;46:101102. doi:10.1016/j.molmet.2020.101102Comprehensive review of GLP-1 RA pharmacology, mechanism, and clinical positioning across the class including semaglutide.
- Hall S, Isaacs D, Clements JN. Pharmacokinetics and clinical implications of semaglutide: a new glucagon-like peptide (GLP)-1 receptor agonist. Clin Pharmacokinet. 2018;57(12):1529–1538. doi:10.1007/s40262-018-0668-zCharacterizes semaglutide PK: Vd ~12.5 L, t1/2 ~165 h, clearance ~0.05 L/h; albumin binding as primary protraction mechanism.
- Overgaard RV, Hertz CL, Ingwersen SH, et al. Levels of circulating semaglutide determine reductions in HbA1c and body weight. Diabetes Obes Metab. 2021;23(10):2149–2159. doi:10.1111/dom.14459Exposure-response analysis across SUSTAIN program showing consistent dose-proportional relationships for HbA1c and weight outcomes.