The figures, for anyone assembling their own picture. Numbers worth memorising for this class: Tmax one to three days for the weekly peptides, terminal half-life about a week for semaglutide and about five days for tirzepatide, steady state at four to five half-lives, subcutaneous bioavailability high enough that site choice is irrelevant.
Worth separating that from the pharmacology, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.
One thing that is still open after carl_compliance’s answer:
How much of the tirzepatide advantage is the GIP component and how much is simply that the dose ladder goes higher in receptor-occupancy terms?
BiostatsBrad said:Numbers worth memorising for this class: Tmax one to three days for the weekly peptides, terminal half-life about a week for semaglutide and about…
There is a second half to this that has not been said yet. The pharmacokinetics explain nearly every practical question asked here. Albumin binding above 99% slows clearance enough to make weekly dosing possible; a terminal half-life near a week means four to five weeks to steady state and therefore a four-week titration interval; subcutaneous bioavailability around 89% means injection site barely matters. Those three facts answer most timing questions before they are asked.
That is the short version; the long version is somebody else's post.
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Browse GL BiochemClosing the loop on my own question.
I stayed at 10mg. Another six months, another 7kg, no new side effects, and my reading of the dose-response says the last two steps were never going to be worth what they cost me.
pete_nash said:The pharmacokinetics explain nearly every practical question asked here.
Agreed on the mechanism, with the caveat that the head-to-head used semaglutide 1mg, not 2.4mg. It is still the best direct evidence available, but it is not the comparison most people think they are citing.