Adding a data point of agreement rather than a data point.
23 likes 18mo
Topic summary
Washout: how long is long enough, and for what purpose
This is a generated summary. It shows the 9 most-liked posts from a topic of 71, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.
batchlog, post #1: Washout: how long is long enough, and for what purpose — setting out what I have, and where I think it stops being reliable. A narrow question about washout, deliberately narrow, because the broad version has been asked here four times and produced four long threads and no answer. One question, stated units, stated method, and what I… Go to post
I had read the opposite somewhere and cannot now find where, which tells me something.
i.amankwah, post #10: 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. If that is already documented somewhere, ignore me and link it. Go to post
Checked the washout claim against the primary source this morning. It survives, with a narrower scope than the version quoted here. Posting the narrower scope.
lc_gradient, post #6: The most useful thing anyone has posted about washout in this category was a table of what had been measured and by whom. That is what I would want again. Go to post
Coming back to post #19, because the follow-up matters more than the original answer.
Where I have landed on washout, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
a.batista, post #4: 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. That much is documented. The rest is how I have interpreted it. Go to post
Thank you for taking the time. That was more work than a reply usually is.
bench_notes, post #2: Adding a data point of agreement rather than a data point. Go to post
I had written a reply contradicting post #29 and deleted it. Here is what survived.
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.
Written quickly, so the reasoning may be tighter than the wording.
o.cousineau, post #24: The confident answers on washout and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category. Go to post
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.
That is a fair summary of where the discussion has got to.
26 likes 13mo
Read the full topic (71 posts)
This topic was referenced in
- Half-life, steady state, and accumulation worked throughPharmacology › Pharmacokinetics · 130 replies
This topic was closed 45 days after the last reply. Closing is automatic for quiet topics so that a settled answer does not collect new questions underneath it. If you have a follow-up, open a new topic and link back to this one — that keeps both readable and gives your question its own title.
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