GLP-1 medications explained
Tirzepatide vs semaglutide: what's the difference?
The short answer: they are different molecules that hit different receptors.Semaglutide is a GLP-1 receptor agonist; tirzepatide is a dual agonist that acts on both the GIP and GLP-1 receptors. Both are peptide medications taken as a weekly injection — but they are not the same drug, and they carry different brand names.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Drug class | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Receptors it acts on | GLP-1 | GIP and GLP-1 |
| Brand names | Ozempic, Rybelsus (type 2 diabetes); Wegovy (weight management) | Mounjaro (type 2 diabetes); Zepbound (weight management) |
| Typical administration | Weekly subcutaneous injection (Rybelsus is a daily tablet) | Weekly subcutaneous injection |
| Molecule type | Peptide | Peptide |
| Tracking in Amidra | Log weekly dose, count remaining, rotate sites | Log weekly dose, count remaining, rotate sites |
Brand availability and approved uses vary by country and change over time — confirm current details with your prescriber or pharmacist.
Semaglutide, in plain English
Semaglutide is a peptide that mimics GLP-1 (glucagon-like peptide-1), one of the body's own incretin hormones. Because it acts on a single receptor, it is described as a GLP-1 receptor agonist. It is sold under several brand names depending on the approved use and formulation — Ozempic and Rybelsus for type 2 diabetes, Wegovy for chronic weight management.
Tirzepatide, in plain English
Tirzepatide is also a peptide, but it acts on two receptors: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1. That "dual agonist" design is the headline chemical difference from semaglutide. It is sold as Mounjaro for type 2 diabetes and Zepbound for weight management.
What's the same: the injection math
Whichever one a prescription is for, the arithmetic behind a compounded vial is identical. Concentration is vial mg ÷ diluent mL; the draw is your dose ÷ concentration; syringe units are the draw in mL × 100 for a U-100 syringe. Pre-filled pens do this internally and need no math at all. The tirzepatide units converter and themg-to-units web converter run these on the numbers from your own label — never a suggested dose.
Common questions
What is the difference between tirzepatide and semaglutide?
They are different molecules that act on different receptors. Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual agonist — it acts on both the GIP and GLP-1 receptors. Both are peptide medications given as a weekly injection, but they are not the same drug and are sold under different brand names.
Are tirzepatide and semaglutide the same brand?
No. Semaglutide is sold as Ozempic and Rybelsus (for type 2 diabetes) and Wegovy (for weight management). Tirzepatide is sold as Mounjaro (for type 2 diabetes) and Zepbound (for weight management). The brand depends on the molecule and the approved use.
Which one is better?
That is a clinical question, not something a tracker can answer. Which medication is appropriate depends on your health, history, and prescriber — Amidra takes no position and never recommends one compound over another. This page only explains what each one is.
Is the reconstitution or unit math different for each?
The arithmetic is identical — concentration is vial mg ÷ diluent mL, and the draw is dose ÷ concentration. What differs is the numbers on your specific vial. Pre-filled pens require no math; compounded vials do. Always use your own label.
Can Amidra track both?
Yes. Amidra logs weekly injections, counts remaining doses, and rotates sites the same way for any GLP-1 medication — you pick the compound during setup. It never suggests a dose or a schedule.