On four-week escalation interval, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.
On the subject in the title: Where the four-week escalation interval comes from, and what it is not Working notes rather than a conclusion.
Working notes on four-week escalation interval rather than a conclusion. I would rather post the reasoning while it can still be corrected than post the answer once I am committed to it.
Everything below is checkable. Where I have taken a figure from somewhere else I have said where; where I have estimated, I have said that too.
Reading this four-week escalation interval thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not.
On four-week escalation interval, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.
Answering the question the opening post raises rather than the one it answers.
The four-week step is a trial convention, not a pharmacological constant. It is roughly four half-lives for a week-long half-life, which is the interval at which you are assessing a stable concentration rather than a rising one.
Speaking for myself and not for anyone else who has posted here.
One caution on four-week escalation interval: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated.
Post #4 describes the usual case. This is about the unusual one.
Concentration and dose get conflated constantly in this subcategory. Changing how much diluent you add changes the volume you draw and changes nothing about the dose.
Someone should write this up properly, and it should probably not be me.
Two sentences on four-week escalation interval and then I will stop, because the rest is speculation and the thread is better without mine.
What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives.
Adding the boring version of four-week escalation interval, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
Picking up post #11: that is the part I would want checked first.
Before the thread moves on from four-week escalation interval — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of four and from an n of four hundred.
I read post #11 twice before replying, because I had assumed the opposite.
Concentration and dose get conflated constantly in this subcategory. Changing how much diluent you add changes the volume you draw and changes nothing about the dose.
Noting that the question and the thing people usually mean by it are different.
Small correction to my own earlier position on four-week escalation interval. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
Worth separating four-week escalation interval as a question about the compound from four-week escalation interval as a question about the documentation. They get answered by different people and only one of them is answerable here.
Narrowing post #19, because the general version has more than one answer.
I disagree with the framing of four-week escalation interval above, and I think it is a substantive disagreement rather than a terminological one. Setting out why, so it can be checked.
The reasoning depends on an assumption that is doing a lot of work and is never stated. If the assumption holds, the conclusion follows. I do not think it holds generally.
Where I would push back on the four-week escalation interval consensus is the confidence, not the direction. The direction looks right. The confidence is borrowed.
Concentration and dose get conflated constantly in this subcategory. Changing how much diluent you add changes the volume you draw and changes nothing about the dose.
Everything in post #22 holds. The case it does not cover is the one I have.
The four-week escalation interval is a convention from the pivotal trials, not a pharmacological constant. The pharmacological argument is that with a week-long half-life, four weeks approaches steady state and you can assess the dose fairly. That is an argument for not going faster. It is not an argument against going slower.
If that reads as pedantic, it is, and it has saved me twice.
Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The published trials used a calendar-based schedule. Tolerability-based escalation has no formal evidence base but is not uncommon in practice.
I would keep four-week escalation interval and the decision it usually gets used for separate in this thread. They are related and they are not the same question, and merging them is why the last one went badly.
Post #24 answers the question as asked. The question underneath it is different.
Two questions I would want answered before drawing anything from the four-week escalation interval data above: how were the cases selected, and what happened to the ones that dropped out.
Confirming post #27 from a second method, which matters more than confirming it from a second person.
Concentration and dose get conflated constantly in this subcategory. Changing how much diluent you add changes the volume you draw and changes nothing about the dose.
I have changed my mind on this once already, so take it as current rather than settled.
I had written a reply contradicting post #26 and deleted it. Here is what survived.
Research-use-only material is not a licensed product and no labelling covers it. Everything in this subcategory about published schedules describes what was done in trials of licensed formulations.
If it helps: the failure mode here is usually boring rather than dramatic.