This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Whatever the answer on Washout turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.
A pharmacokinetic model fitted to trial data describes the population studied. Applying it to somebody outside the enrolled range is an extrapolation, and the model will not tell you it is.
Appreciated. The plain phrasing does more work here than a longer post would.
Where two sources give different half-lives, check the study design before deciding either is wrong. Sampling duration, assay sensitivity and population all move the number.
That has been true for the cases I have seen and I have not seen many.
Post #123 and I disagree about the size of the effect, not about the direction.
Washout after stopping takes roughly the same four to five half-lives as reaching steady state. A month after the last dose is not the same as none.
That is the shape of it. The detail is where I would expect to be corrected.
Taking post #127 at face value and following it one step further.
Reading this Washout thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not.
Adding the measurement that post #127 says would settle it.
Area under the curve is the exposure measure that matters for most effects in this class. Peak concentration matters more for tolerability.
Adding it because I spent an afternoon working it out and nobody should have to twice.
Adding a null result on Washout. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.
This follows post #130 rather than contradicting it.
Metabolism for peptide drugs is proteolytic rather than hepatic in the usual sense, which is why the cytochrome interaction questions that dominate small-molecule pharmacology mostly do not apply.
I have separated what I observed from what I concluded, which does not always happen.
Worth separating two things that post #133 runs together.
Washout would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein. That is relevant to understanding how much free drug is available.
Post #136 and I disagree about the size of the effect, not about the direction.
Two claims get bundled together under Washout and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not.
Almost every disagreement in threads like this one dissolves once you say which of the two you are making.
This is the first time the answer has come with its own limits attached. Appreciated.
Answering the question post #136 raises rather than the one it answers.
Half-life: semaglutide ≈ 165–184 hours (about a week). Tirzepatide ≈ 5 days. Liraglutide ≈ 13 hours. The half-life determines how much accumulation happens at steady state and how long it takes to clear after stopping.
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