GLP1 MathCompounded vs brand GLP-1: what's different
Brand products such as Wegovy, Ozempic, Zepbound and Mounjaro are FDA-approved and come in pens (and, for Zepbound, single-dose vials) with fixed doses. Compounded versions are prepared by pharmacies, usually as multi-dose vials that you draw with a syringe.
How you measure changes
With a brand pen you select a dose in mg. With a compounded vial you convert mg into units on a syringe, which depends on the vial strength. Different pharmacies use different strengths, so the units can change even when your dose doesn't.
Questions to ask your pharmacy
- What is the strength in mg per mL, exactly as printed on my vial?
- Which syringe size should I use?
- How should the vial be stored, and how long is it good after opening?
- Does this vial contain any added ingredients?
The FDA's position
The FDA does not review compounded drugs for safety or effectiveness before they are sold, and it has published warnings about dosing errors with compounded semaglutide. Getting the units right is the most common place people slip.