Quick answer
Semaglutide (GLP-1 agonist, 31 residues) and tirzepatide (dual GIP/GLP-1 agonist, 39 residues) are different molecules; verify purity by HPLC and identity by mass.
- Brand names: Ozempic and Mounjaro are formulated products; V8 sells unformulated research peptide only
- Receptors: GLP-1 only vs. GIP + GLP-1
- Verify: HPLC purity, mass (about 4.11 vs. 4.81 kDa), lot-matched COA
- Listings: semaglutide 10 mg, tirzepatide 30 mg; COA page
- Research use: For laboratory research use only; not for human consumption.
For laboratory research use only; not for human consumption.
Searches for "Ozempic alternative" or "Mounjaro alternative" are common, and some of that traffic is really looking for the research compounds behind those brand names, semaglutide and tirzepatide, rather than a medication. This guide is for that second group: researchers who want unformulated, research-grade semaglutide or tirzepatide for laboratory work and need to know how the two compounds differ and what to verify before sourcing either.
Brand names are not the research compounds
Ozempic, Wegovy and Rybelsus are FDA-approved branded medicines made by Novo Nordisk; their active ingredient is semaglutide. Mounjaro and Zepbound are FDA-approved branded medicines made by Eli Lilly; their active ingredient is tirzepatide. V8 Peptides has no affiliation with either manufacturer, does not sell those branded products and does not offer a substitute for them. What V8 supplies is the unformulated peptide itself as a lyophilized research reagent. A branded product contains excipients, a specific formulation and a delivery device; a research vial contains only peptide powder, and neither is interchangeable with the other. The brand names appear here only so that researchers searching by familiar terminology can find the right compound pages. See also tirzepatide and its brand-name chemistry and what semaglutide is.
Semaglutide vs. tirzepatide: the molecules
Both are incretin-class peptides acylated with a fatty diacid to promote albumin binding, and both contain the non-natural residue aminoisobutyric acid (Aib) to resist dipeptidyl peptidase-4 cleavage. The pharmacological difference is in receptor coverage: semaglutide is a selective GLP-1 receptor agonist, while tirzepatide is engineered to activate both the GIP receptor and the GLP-1 receptor (Coskun et al., 2018).
| Property | Semaglutide | Tirzepatide |
|---|---|---|
| Receptor target | GLP-1 receptor | GIP and GLP-1 receptors |
| Chain length | 31 residues | 39 residues |
| Formula (per V8 listing) | C187H291N45O59 | C225H348N48O68 |
| Approximate average mass | About 4.11 kDa | About 4.81 kDa |
| Lipid modification | C18 diacid via linker on a lysine | C20 diacid via linker on a lysine |
| V8 vial size | 10 mg | 30 mg |
| Product page | Semaglutide | Tirzepatide |
Which compound suits which study? Choose semaglutide when the question is isolated GLP-1 receptor signaling, and tirzepatide when the design asks about GIP and GLP-1 receptors acting together. A cell line expressing only the GLP-1 receptor will not show the GIP component of tirzepatide. Mechanism and comparison are in semaglutide vs. tirzepatide, with broader context in GLP-1 receptor agonists in research and the compound guides semaglutide research overview and tirzepatide research overview.
What to check before sourcing either compound
- Measured purity. A specific HPLC value with the method visible, not a bare label claim. See HPLC purity analysis.
- Identity by mass spectrometry. Semaglutide and tirzepatide are different chains with different masses (about 4.11 and 4.81 kDa), but can look alike on a basic HPLC trace, since both are lipidated and elute late. Mass is what distinguishes them. See HPLC vs. mass spectrometry.
- Batch-specific COA tied to the lot shipped. See how to read a COA.
- Independent testing in addition to in-house data. See third-party testing explained.
- Research-use-only labeling with accurate reconstitution and storage documentation.
- Stated vial content and whether it refers to peptide mass or gross powder (which includes counter-ions and water).
A wider supplier checklist is in choosing a peptide supplier, and the compound-specific testing approach for each is in semaglutide purity testing and tirzepatide purity testing.
Why the two differ in cost to produce
Tirzepatide is the longer chain (39 vs. 31 residues) with two Aib residues rather than one, and both carry a lipid side chain that requires a separate conjugation step. Longer sequences accumulate more deletion and truncation by-products, so reaching the same purity grade needs more purification. The size of the vial matters as well: a 30 mg vial contains three times as much peptide as a 10 mg vial. The mechanics are discussed in tirzepatide pricing: what drives the cost. Compare listings per milligram of verified peptide, not per vial.
Reconstitution and handling
Both compounds ship as lyophilized powder and are brought into solution for laboratory work with a diluent such as bacteriostatic water. Concentration is peptide mass divided by diluent volume. For example, 10 mg of semaglutide in 2 mL is 5 mg/mL, and 30 mg of tirzepatide in 3 mL is 10 mg/mL; the calculator returns the same arithmetic for other volumes. Storage is 2–8 °C, with −20 °C for long-term storage, protected from heat, moisture and light, per the V8 listings. Because lipidated peptides can adsorb to surfaces and aggregate under vigorous agitation, swirl gently rather than shaking. Compound-specific notes are in semaglutide reconstitution and handling, tirzepatide reconstitution and handling and tirzepatide storage and stability. V8 also stocks bacteriostatic water.
Common mix-ups to avoid
- Salt and sub-name confusion. Some marketing refers to "semaglutide sodium" or "semaglutide acetate." These are salt forms of the same peptide with slightly different masses and net peptide content; the COA should say which form the lot is.
- Vial size versus peptide content. A 10 mg or 30 mg label is the intended net quantity, but if it reflects gross powder, the peptide mass is lower. Ask how quantity was determined.
- Compounded or "generic" claims. A research reagent is not a generic version of a branded medicine, and V8 does not describe it as one.
- Blend assumptions. Combination products such as cagrilintide plus semaglutide are separate materials with their own verification needs; see CagriSema combination research.
- Related compounds. Retatrutide, a triple agonist, is a different molecule again; see the retatrutide research overview.
Documentation at a glance
| Document or check | Why it matters for this pair |
|---|---|
| HPLC chromatogram | Shows the purity figure and whether closely eluting impurities are resolved |
| Mass spectrum with observed mass | Separates semaglutide from tirzepatide and shows whether the lipid side chain is present |
| Lot number on COA and vial | Links the data to your material |
| Test date | Establishes the age of the data relative to storage |
| Storage guidance | Both are sensitive once in solution |
Where to buy research-grade semaglutide and tirzepatide
V8 Peptides supplies both compounds as lyophilized powder with ≥98% HPLC purity stated on each product page. Semaglutide (10 mg) is on the semaglutide research vial page and tirzepatide (30 mg) on the tirzepatide research vial page. The tirzepatide page links a lot-specific COA, while the semaglutide page currently shows its COA status as in progress, so check both before ordering; batch records are on the COA page. Sourcing checklists specific to each compound are in where to buy semaglutide and where to buy tirzepatide. For related incretin compounds and a four-way comparison, see the 2026 GLP-1 research comparison.
Frequently asked questions
Is research semaglutide the same as Ozempic?
No. Ozempic is a formulated branded medicine from Novo Nordisk. A research vial contains unformulated peptide powder for laboratory use only. V8 is not affiliated with either manufacturer.
What is the main difference between semaglutide and tirzepatide?
Semaglutide activates the GLP-1 receptor only; tirzepatide activates both the GIP and GLP-1 receptors. Tirzepatide is also longer, 39 residues vs. 31.
How do I tell them apart analytically?
By mass: about 4.11 kDa for semaglutide and about 4.81 kDa for tirzepatide. HPLC retention alone can be misleading because both are lipidated and elute late.
Why does tirzepatide cost more per vial?
It is a longer chain with more purification burden, and V8's tirzepatide vial is 30 mg against 10 mg for semaglutide. Compare per milligram of verified peptide.
Which vial sizes does V8 list?
Semaglutide 10 mg and tirzepatide 30 mg, per the semaglutide and tirzepatide product pages.
How is stock concentration calculated?
Peptide mass divided by diluent volume. 10 mg in 2 mL is 5 mg/mL; 30 mg in 3 mL is 10 mg/mL. Use the calculator for other volumes.
How should these be stored?
Per the listings: refrigerate at 2–8 °C, freeze at −20 °C for long-term storage, and protect from heat, moisture and light.
Where do I find the COA?
On the COA page. The tirzepatide product page links a lot COA; the semaglutide page currently shows its COA as in progress.
Research Use Only. For laboratory research use only; not for human consumption. Supplied strictly for laboratory research and development, not for human or veterinary use, and not for any diagnostic or clinical purpose. This article is research education, not usage guidance.
References
- Lau J, Bloch P, Schäffer L, et al. Discovery of the once-weekly glucagon-like peptide-1 (GLP-1) analogue semaglutide. J Med Chem. 2015;58(18):7370-7380.
- Coskun T, Sloop KW, Loghin C, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist: from discovery to clinical proof of concept. Mol Metab. 2018;18:3-14.
- Semaglutide research overview
- Tirzepatide research overview
- Semaglutide vs. tirzepatide
- How to read a COA