Collecting this in one place because it comes up every few weeks and the answer is always assembled from scratch. It is about semaglutide, and it is deliberately narrow — everything I am not confident about is marked as such.
What is actually established
The mechanism that matters here is not stomach emptying, it is central. GLP-1 receptor agonism in the arcuate nucleus stimulates POMC neurons and suppresses AgRP/NPY signalling, which is why the effect is appetite and food salience rather than physical fullness. Delayed gastric emptying largely tachyphylaxes over the first months; the appetite effect does not.
The condition it depends on
One condition: that curve is for people who reached the dose on schedule. Anyone who slowed the ladder for tolerability is on a different, flatter curve, and comparing yourself with the published mean will make you feel like a non-responder when you are not.
The practical version
For anyone assembling their own picture: Tmax is one to three days, terminal half-life about 165 to 170 hours, steady state at four to five weeks, and subcutaneous bioavailability near 89%. Those four numbers explain most of the questions people ask about timing.
What I am not sure about
What I am trying to establish is whether anyone has held at a sub-maximal dose long term and kept the result, or whether the maintenance data only exists at 2.4mg. I would rather have one careful answer than five confident ones.
Dr.RaviCardio said:The mechanism that matters here is not stomach emptying, it is central.
That holds for the injectable. The oral formulation has different absorption behaviour and the dose numbers are not interchangeable, which is worth saying out loud because people quote them as if they were.
Dr.RaviCardio said:The mechanism that matters here is not stomach emptying, it is central.
This is where I part company with the consensus forming above. The trial means are being read too generously in this thread. STEP populations were selected, supported, and titrated by protocol, and the real-world curves are consistently a few points worse. That difference is not noise, it is what happens when you remove the study infrastructure.
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Browse GL BiochemThis one has a reasonably settled answer, so here it is. Albumin binding above 99% is the whole reason weekly dosing works, and it is also why the trough matters more than the peak. People who dose late are not losing a peak, they are letting the trough fall, and the appetite effect tracks the trough.
CarlaRPh_TPA said:The oral formulation has different absorption behaviour and the dose numbers are not interchangeable, which is worth saying out loud because people…
Agreed, though "tolerable" needs defining. A dose you tolerate by eating almost nothing is not tolerated, it is being paid for somewhere else — usually in lean mass, sometimes in adherence three months later.