[2026 update] Comparing tirzepatide and semaglutide is harder than the tables suggest

Comparing tirzepatide and semaglutide is harder than the tables suggest Writing it up because I had to work it out twice and would rather nobody else did.

Putting the numbers in the first post, because a question about a compound without them turns into a question about somebody's impression of it.

semaglutide, monoisotopic mass near 4113.6 Da, 16 weeks of my own notes, and 8 lots from 3 suppliers with a purity figure on each. That is the whole basis of what follows.

What I want checked is the reasoning I have built on top of it, not the figures themselves.

The five maintenance doses in the tirzepatide programme give a genuine dose-response curve, which is unusual. Most trials in this space compare one or two doses against placebo and cannot say anything about the shape of the relationship.

Speaking for myself and not for anyone else who has posted here.

Storage and stability: published data on licensed tirzepatide formulations exists and is worth reading directly rather than through summarised claims. Reconstituted preparations in different diluents have not been studied and extrapolation from the licensed formulation is the best you can do.