Ozempic, Wegovy, and Mounjaro: the differences between the brands

Research use only. This content is for laboratory research; not for human or veterinary use, diagnosis, or treatment.

Producto para uso experimental en laboratorio. No es medicamento ni producto de consumo humano.

Ozempic, Wegovy, and Mounjaro are three of the most-searched brands in the metabolism and incretin-agonist conversation. They are often confused because they are brand names, not molecules. This guide maps each brand to its active ingredient, explains how the mechanisms differ according to the literature, and clarifies the line between the approved medicine and the research compound (RUO). Brands are named for recognition only; this is not a usage guide.

Which brand is which molecule

Ozempic® and Wegovy® are brands of the same molecule: semaglutide, a GLP-1 receptor agonist from Novo Nordisk (Ozempic® is approved for type 2 diabetes and Wegovy® for weight management). Mounjaro® and Zepbound® are brands of a different molecule: tirzepatide, a dual GIP and GLP-1 receptor agonist from Eli Lilly. In short: two brands for semaglutide, two brands for tirzepatide.

One receptor vs two receptors

The design difference between the two molecules is how many incretin receptors they activate. Semaglutide acts on a single receptor, GLP-1, associated with satiety and glucose-dependent insulin secretion. Tirzepatide activates two receptors at once — GLP-1 and GIP; the GIP component is associated in the literature with insulin sensitivity and lipid metabolism. That dual activation is the feature that separates tirzepatide from single-receptor agonists.

What the published evidence shows

Both molecules have human clinical-trial programs. For semaglutide, the STEP 1 trial — published in the New England Journal of Medicine — reported body-weight reductions in its study cohort ^[1]. For tirzepatide, SURMOUNT-1 reported notable weight reductions in its cohort ^[2], and SURPASS-2 compared it directly with semaglutide in type 2 diabetes, reporting greater A1C and weight reductions in the groups evaluated ^[3]. These are human studies cited purely as scientific context for each molecule; they are not a usage guide or an administration recommendation.

Approved medicine vs research compound

This is the distinction that matters most. Ozempic®, Wegovy®, Mounjaro®, and Zepbound® are approved, prescription medicines, manufactured under pharmaceutical standards for human use. When a lab sources “tirzepatide” for research, it acquires a reagent in lyophilized form intended for in-vitro protocols and preclinical models, under the research-use-only (RUO) category. It is not the medicine and must not be presented or used as a substitute for it. A serious research supplier keeps this line clear.

How to evaluate tirzepatide quality for research

For a lab, what defines a good purchase is documentation:

1. Lot-specific certificate of analysis (COA) with HPLC (reverse-phase) purity and mass-spectrometry (MS) identity confirmation.
2. Traceability: a lot number and analysis date that map to the vial you received.
3. Endotoxin (LAL) testing where the in-vitro protocol requires it.
4. Documented storage conditions and stability data for the lyophilized material.

In short: Ozempic® and Wegovy® are semaglutide; Mounjaro® and Zepbound® are tirzepatide. Of these molecules, tirzepatide is the one we distribute for research as an RUO reagent — not as a substitute for the medicine. If your work requires tirzepatide for research, prioritize the lot with a verifiable COA and documented purity above any other consideration.