semaglutide
What is semaglutide
semaglutidee is the first GLP-1 receptor agonist to reach the mass market. The drug was developed by Novo Nordisk, the EU approval came in 2018 for type 2 diabetes (brand name Ozempic), 2022 followed the obesity indication (Wegovy). An Oral variant has been available since 2020 under the name Rybelsus.
Chemically, semaglutide is a modified GLP-1 analogue, 31 amino acids long, with a C18 fatty acid anchor that allows binding to albumin, thus extending the half-life to around one week. CAS No: 910463-68-2. Molecular weight: 4113.58 g/mol.
Mechanism of action
GLP-1 (Glucagon-like Peptides 1) is a body's own incretin hormone that is released from the intestine after a meal. semaglutidee mimics this effect but is resistant to degradation by DPP-4. This results in four main mechanisms.
First, it increases glucose-dependent insulin secretion from the pancreatic beta cells. Second, it suppresses glucagon secretion. Third, it slows gastric emptying, leading to longer satiety. Fourth, it acts centrally in the hypothalamus on appetite circuits that increase satiety and dampen reward-driven eating.
In the STEP-1 study (Wilding et al., NEJM, 2021), 2.4 mg weekly at 68 weeks resulted in a mean weight loss of 14.9 percent. In diabetes patients, the effect is slightly less.
Areas of application in research
- Type 2 diabetes: First-line add-on in case of insufficient metformin control
- Obesity: BMI ≥30 or ≥27 with comorbidity
- Cardiovascular risk reduction: SELECT study showed 20 percent reduction in MACE in patients with obesity and cardiovascular pre-existing disease
- Renal failure: FLOW study 2024, significant reduction of kidney endpoints in T2D
- NASH/MASLD: ESSENCE study ongoing, early data positive
Study situation
The evidence base is extensive. STEP program (8 studies) for obesity, SUSTAIN program (10 studies) for diabetes, plus SELECT (cardiovascular outcomes), FLOW (kidney) and ESSENCE (liver).
Key results:
- STEP-1 (2021): 14.9 percent weight loss after 68 weeks with 2.4 mg
- SUSTAIN-6 (Marso et al., NEJM, 2016): 26 percent reduction in cardiovascular endpoints
- SELECT (Lincoff et al., NEJM, 2023): 20 percent MACE reduction in obesity plus CVD
- FLOW (2024): prematurely discontinued due to effectiveness
Open questions: long-term compliance beyond 5 years, rebound after discontinuation (about two-thirds of the weight lost comes back within a year), effects on muscle mass and bone density.
Mixing (reconstitution)
Pharmaceutical products (Ozempic, Wegovy) are finished pens, no mixing necessary. For research lyophilisate:
- Typical vials: 5 mg or 10 mg
- 5-mg Vial with 1 ml of bacteriostatic water → 5 mg/ml
- 5-mg Vial with 2 ml → 2.5 mg/ml for finer dosage
- Cooling 2 to 8 degrees after mixing, stability around 4 to 6 weeks
Dosage range (research data)
Established escalation according to specialist information:
- Diabetes (Ozempic): Start 0.25 mg/week, after 4 weeks 0.5 mg, optionally 1 mg, max. 2 mg
- Obesity (Wegovy): escalation over 16 weeks, target dose 2.4 mg/week
- Oral (rybelsus): 3 mg daily, escalation to 7 mg, then 14 mg
Subcutaneous injection, weekly, always on the same weekday.
Side effects
Well documented after millions of patient years:
- Nausea (often, usually in the first 4 to 8 weeks)
- Vomiting, diarrhoea, constipation
- Reflux, heartburn
- Reactive hypoglycemia (rarely, rather when combined with sulfonylureas)
- Pancreatitis (rare, FDA warning)
- Gallbladder diseases
- Increased risk of medullary thyroid carcinoma (black box warning, based on rodent studies)
- Loss of muscle mass, estimated 25 to 40 percent of total weight loss is fat-free mass
- 'Ozempic Face': Loss of face volume due to rapid fat loss
Half-Life and Pharmacokinetics
Elimination half-life: approximately 7 days. Steady-state after 4 to 5 weeks. Bioavailability subcutaneously about 89 percent. Oral bioavailability (rybelsus) is significantly lower, about 1 percent, hence the high Oral doses.
metabolism via proteolytic cleavage. No relevant CYP interaction. Excretion mostly renal as metabolites.
Frequent questions
When does the effect occur? Appetite reduction often within 1 to 2 weeks, significant weight loss after 8 to 16 weeks.
Do I need to take semaglutide permanently? Clinical data show that after discontinuation, around two-thirds of the weight will return within a year. Practically, it is therefore a long-term therapy.
How much does Ozempic cost in Germany? On private prescription about 130 euros for 1.5 ml (equivalent to 4 weeks at 1 mg. Cash performance only for T2D indication.
Why is semaglutide partly unavailable? Global demand has exceeded Novo Nordisk production capacity since 2022. Situation 2026 somewhat more relaxed, but not yet completely stable.
Is semaglutide the same as ozempic? Yes, semaglutide is the active ingredient, Ozempic and Wegovy are brand names with different dosage profiles.
Legal status U.S.
As of 2026: semaglutidee is approved as a medicine in Germany, Austria and Switzerland and is subject to pharmacy requirements. Prescription only by doctor. Assumption of costs by GKV at T2D, for obesity usually self-payers.
Purchase outside the pharmacy (online shops, research vials) does not meet the requirements of pharmaceutical law and is not covered for self-use.
Related compounds
- liraglutide: daily dose GLP-1, predecessor of semaglutide (Saxenda, Victoza)
- tirzepatideDual agonist with stronger weight effect (Mounjaro)
- retatrutideTriple agonist in Phase 3
- exenatideFirst GLP-1 generation
- dulaglutideWeekly GLP-1 agonist (Trulicity)
Note: All information is for research information only. These peptides are not approved as medicines in Germany. The contents do not replace medical advice. Application to humans is not legally covered in Germany.