Semaglutide 5 mg/10mg – GLP-1 receptor agonist

What is Semaglutide?

Semaglutide (also known as semaglutide) is a synthetic, long-acting GLP-1 receptor agonist (glucagon-like peptide-1). It is an acylated analog of human GLP-1 in which an attached fatty-acid residue provides strong binding to albumin — which gives the molecule a long half-life and enables once-weekly dosing. In the clinical literature, Semaglutide is described as one of the best-studied agonists of the GLP-1 class, with data on glucose-dependent insulin secretion and metabolic markers.

Semaglutide is a mono-agonist — it acts only on the GLP-1 axis. This distinguishes it from the dual agonist Tirzepatide (GLP-1/GIP) and the triple agonist Retatrutide (GLP-1/GIP/glucagon). In publications, Semaglutide is often used as the reference GLP-1 agonist against which newer multi-receptor molecules are compared.

The research-grade Semaglutide offered by Peptology is not a registered medicine — it is a lyophilized research peptide intended exclusively for scientific and in vitro applications, not intended for use in humans or animals. See also the other peptides for weight loss (GLP-1) in our category.

In the version offered by Peptology, Semaglutide is supplied as a lyophilized peptide with purity above 99% (HPLC/MS), confirmed by independent laboratory analysis (CoA for every batch). It is available in two vial formats — 5 mg and 10 mg — depending on the scale of the research protocol.

Available formats: 5 mg and 10 mg

Semaglutide is available in two lyophilized formats, which cover different research-work scales — from single in vitro series to longer protocols with higher peptide consumption.

Both formats have identical purity > 99% and the same laboratory certificate for the batch. The choice of size depends on the scale of the protocol, not on the concentration of the active substance.

How Semaglutide works — GLP-1 receptor agonism

GLP-1 receptors are found in the pancreas, brain and gastrointestinal tract. In clinical and preclinical publications, Semaglutide is described as a molecule that activates these receptors and produces several complementary metabolic effects. The main parameters studied are glucose-dependent insulin secretion, glucagon secretion and gastric emptying.

Why the GLP-1 axis matters

GLP-1 is an incretin secreted after a meal that simultaneously regulates insulin secretion, glucagon secretion and gastric emptying. Semaglutide's long half-life — a result of albumin binding — maintains continuous activation of this axis throughout the week, which distinguishes it from short-acting GLP-1 analogs. In studies, this profile is linked to improved glycemic markers.

Semaglutide is a point of reference for newer multi-receptor molecules. The dual agonist Tirzepatide adds the GIP axis, and the triple agonist Retatrutide — additionally the glucagon axis. The results presented come from controlled clinical trials and do not constitute a claim about the effect of the research-grade product.

Pharmacokinetics and pharmacodynamics of Semaglutide

Semaglutide is an acylated GLP-1 analog which, in published pharmacokinetic data, is described as a molecule with a long half-life thanks to strong binding to albumin — which explains the weekly dosing schedule used in clinical protocols.

• Biological half-life: about 7 days (~168 h), which enables once-weekly dosing
• Long-action mechanism: strong binding to albumin thanks to an attached fatty-acid residue, slow elimination
• Dosing schedule: once a week subcutaneously (SC), with dose titration over time
• Steady state: reached after about 4–5 weeks of dosing at a given dose level
• Route of administration: subcutaneous (weekly forms) or oral (in separate pharmaceutical preparations)
• Dose studied in phase 3 (obesity, STEP): 2.4 mg SC weekly, with titration from a lower dose

Semaglutide vs Tirzepatide vs Retatrutide

The table below compares Semaglutide with two newer multi-receptor molecules from the incretin family in the research-peptide catalog. All three are studied with respect to glucose metabolism, but they differ in the number of activated receptor axes — Semaglutide acts on one (GLP-1), Tirzepatide on two (GLP-1/GIP), and Retatrutide on three (GLP-1/GIP/glucagon). The data are of a scientific-comparative nature and do not constitute a direct head-to-head comparison.

Sources: Wilding et al., STEP 1, New England Journal of Medicine (2021); the SUSTAIN program (type 2 diabetes); the SELECT study (cardiovascular outcomes, NEJM 2023, n=17,604). The data presented come from different clinical programs and should not be interpreted as a direct comparison or as a claim about the effect of a specific research-grade product.

Clinical trials of Semaglutide

Semaglutide is among the best-studied GLP-1 agonists. The clinical program covers three large lines — type 2 diabetes (SUSTAIN), obesity (STEP) and cardiovascular outcomes (SELECT). These results concern the pharmaceutical forms of semaglutide and come from controlled clinical trials.

Phase 1 — safety and pharmacokinetics

Early clinical studies documented good tolerability, a long half-life (~7 days) resulting from binding to albumin, and the achievement of steady state after 4–5 weeks of weekly dosing.

SUSTAIN — type 2 diabetes

The SUSTAIN program evaluated semaglutide in patients with type 2 diabetes, demonstrating a significant reduction in HbA1c and body weight compared with placebo and other antidiabetic medicines.

STEP 1 — obesity (NEJM, 2021)

In the phase 3 STEP 1 study, adults with obesity or overweight received semaglutide 2.4 mg SC weekly or placebo for 68 weeks, together with a lifestyle change. The mean body-weight reduction was −14.9% in the semaglutide group versus −2.4% in the placebo group, and a body-weight reduction of ≥ 5% was achieved by 86.4% of participants (versus 31.5% in the placebo group). These results come from a controlled clinical trial and do not constitute a recommendation for individual use.

SELECT — cardiovascular outcomes

In the SELECT study (17,604 participants with cardiovascular disease and overweight/obesity, without diabetes), semaglutide 2.4 mg was linked to a 20% reduction in the risk of major adverse cardiovascular events (MACE) — cardiovascular death, heart attack or stroke — compared with placebo. These are data from a controlled clinical trial.

Note: The clinical trial information concerns the pharmaceutical forms of semaglutide and is presented for scientific and informational purposes. It does not constitute medical advice, a recommendation for use or a claim about the effect of the research-grade product offered by Peptology.

Documented clinical results for Semaglutide

• One of the best-studied GLP-1 agonists — the reference mono-agonist in the literature
• Mean body-weight reduction of ~14.9% over 68 weeks in phase 3 STEP 1 (NEJM, 2021)
• A ≥ 5% body-weight reduction in 86.4% of participants in STEP 1
• 20% reduction in MACE risk in the cardiovascular SELECT study (n=17,604)
• Significant reduction in HbA1c in type 2 diabetes in the SUSTAIN program
• Long half-life (~7 days) thanks to albumin binding — once-weekly dosing

All results given concern published clinical trials of the pharmaceutical forms of semaglutide and should not be interpreted as a promise of effect, an instruction for use or a claim about the effect of the research-grade product offered by Peptology.

Research dosing protocols

In clinical programs, semaglutide was used in a weekly subcutaneous schedule with gradual dose titration — which aims to improve gastrointestinal tolerability:

• Phase 1 (dose escalation): a range of SC doses within the research protocol, with titration from a low dose
• Phase 3 (obesity, STEP): titration to 2.4 mg SC once a week as the studied target dose
• Type 2 diabetes (SUSTAIN): weekly SC doses in a lower range, according to the protocol
• Cardiovascular study (SELECT): 2.4 mg SC weekly

Like Tirzepatide and Retatrutide, Semaglutide in studies requires slow titration to improve tolerability — patients were started on a lower dose and it was gradually increased. These schedules are part of controlled clinical trials and do not constitute a recommendation for self-administration.

Storage and reconstitution

Semaglutide is supplied as a lyophilized (freeze-dried) powder in a vial. In lyophilized form the peptide is stable at room temperature, protected from light and moisture — refrigeration before reconstitution is not mandatory. After reconstitution, stability depends on the solvent used, with Peptide Matrix Water™ significantly extending the peptide's lifespan.

• Before reconstitution: room temperature, in the original packaging, protected from light and moisture. A refrigerator is not mandatory.
• After reconstitution with Peptide Matrix Water™: stability in the refrigerator +2 °C to +8 °C for up to 60 days under appropriate laboratory conditions — the stabilizing formula extends the peptide's lifespan relative to standard solvents.
• After reconstitution with bacteriostatic or sterile water: stability in the refrigerator +2 °C to +8 °C for up to 28 days under appropriate conditions. Do not refreeze the reconstituted solution.
• Reconstitution: in a laboratory environment, Peptide Matrix Water™, bacteriostatic water or sterile water for injection is usually used, depending on the protocol.
• Volume: maximum 3 mL of solvent (capacity of a standard vial). For a precise calculation of volume and units, use the peptide calculator.
• Homogenization: add the solvent slowly down the vial wall, without vigorous shaking — peptide bonds are sensitive to mechanical stress. Swirl gently, do not shake.

Laboratory tip: With your order, you can add Peptide Matrix Water™ to the cart — a stabilizing solution designed for working with reconstituted research peptides, including GLP-1 agonists. More in the article Bacteriostatic water vs acetic acid vs matrix water.

Frequently asked questions about Semaglutide

What exactly is Semaglutide?

Semaglutide is a synthetic, long-acting GLP-1 receptor agonist. It mimics the action of the incretin GLP-1, which regulates insulin secretion, glucagon secretion and gastric emptying. In clinical trials it is one of the most frequently evaluated peptides in the context of obesity and type 2 diabetes. The results come from controlled clinical trials.

How does Semaglutide differ from Tirzepatide and Retatrutide?

All three are studied with respect to glucose metabolism, but they differ in the number of receptor axes. Semaglutide acts only on the GLP-1 axis, Tirzepatide combines GLP-1 and GIP, and Retatrutide adds a third axis — the glucagon receptor. In studies, Semaglutide often serves as the reference against which the newer multi-receptor molecules are compared.

What is the half-life of Semaglutide?

The biological half-life of semaglutide is about 7 days thanks to strong binding to albumin, and steady state is reached after 4–5 weeks. This is why clinical protocols use a weekly schedule — similar to Tirzepatide or Retatrutide.

Which format to choose — 5 or 10 mg?

Both formats have identical purity > 99% and the same batch certificate. The choice depends on the scale of the protocol: 5 mg for single validation series and shorter protocols, and 10 mg for longer, repeated models with higher peptide consumption.

How is Semaglutide stored and reconstituted?

The lyophilized vial is stored at room temperature, protected from light and moisture — without the need for cooling before reconstitution. After reconstitution, stability depends on the solvent: with Peptide Matrix Water™ — up to 60 days in the refrigerator +2 °C to +8 °C; with bacteriostatic or sterile water — up to 28 days. In all cases avoid refreezing.

Where to buy Semaglutide for research?

Peptology offers Semaglutide as a research peptide with confirmed purity above 99% (HPLC/MS) and independent laboratory analysis for every batch. Fast shipping, discreet packaging and certificates of purity with the product. For scientific background, also see the article Peptides — what they are, how they work, main categories and safety profile.

Related peptides in the Peptology catalog

Researchers working with Semaglutide often also consider other molecules from the GLP-1 / incretin agonist class and solutions for reconstitution. Each of the products below has a certificate of purity above 99%:

See the full catalog: Peptides for weight loss (GLP-1) · Solutions for peptides · Blog on peptide research

Molecule identity

References

1. Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384:989–1002.
2. Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. N Engl J Med. 2023;389:2221–2232.

Laboratory reconstitution

Laboratory protocol — reconstitution, research protocols, storage

Standardized protocol applicable to all research peptides in the Peptology catalogue. To calculate the solution concentration (mg/mL) for each vial, use the peptide reconstitution calculator.

60-second protocol

Quick reference

What you need

Five rules for reconstitution

Calculating concentration

Storage

Four mistakes to avoid

Shipping information

🚚 Shipping information

• Products in our warehouse – orders placed by 15:00 on working days are dispatched the same day, later orders on the next working day.

• Delivery with GLS to your address in 3–5 working days.

• Shipping costs €5 and is free from €50.

Frequently Asked Questions (FAQ)

In what form is Semaglutide supplied and how should it be stored?

It is supplied as a lyophilized (freeze-dried) powder in a sealed vial. Store the unopened vial dry and protected from light, ideally at 2–8 °C. After laboratory reconstitution, keep the solution at 2–8 °C and use it within the period stated in the “Laboratory reconstitution” tab (up to 60 days with Peptide Matrix Water).

What purity does Semaglutide have and how is it tested?

Every batch has a purity of 99% or higher, confirmed by HPLC and mass spectrometry (MS) and documented in a certificate of analysis (CoA). The report for the current batch is shown in the “Laboratory Analysis” tab.

Is a prescription required?

No. Offered for research purposes, without the need for a prescription.

Where can I buy Semaglutide in Europe and what does it cost?

You can buy Semaglutide in Europe online from Peptology, from 50,00 €. Delivery with GLS in 3–5 working days. Shipping is free from 50,00 €. Payment by card or bank transfer. Purity 99%+, with an HPLC report for every batch.

Laboratory Analysis

Semaglutide - 5mg - Batch - 0226 - Purity & Endotoxins 

Semaglutide - 10mg - Batch - 0226 - Purity & Endotoxins