Where I part company with post #5, and it is a narrow parting. Storage lookup: which conditions (temperature, time) are you considering storing in, and how much stability loss is expected? The calculator gives a rough estimate based on typical stability data. Not a substitute for your compound's specific stability…
A calculator that gives a right answer to the wrong question — does this still hold? I have a specific reason for asking rather than idle curiosity, and the context is below.
Posting the calculation with the inputs, so that somebody can disagree with a step rather than with the answer.
Inputs: 5 mg in 3 mL, target 0.5 mg, U-100 barrel. Working shown below in the order I did it.
I have checked it twice by the same route, which is not the same as checking it twice.
Nobody has said the unglamorous part of calculator yet, so: most of the variation is explained by things that are boring to write about and easy to check.
Thank you — that answers what I came here to find out.
Building on the opening post rather than restating it.
Why calculators are not medical advice: they do arithmetic. Medical decisions are not arithmetic. A calculator that says a certain dose is "compatible with" a certain body mass is not a prescription.
I would rather say I do not know than round it up to an answer.
Where I part company with post #5, and it is a narrow parting.
Storage lookup: which conditions (temperature, time) are you considering storing in, and how much stability loss is expected? The calculator gives a rough estimate based on typical stability data. Not a substitute for your compound's specific stability data.
Caveat: everything above assumes the paperwork is what it says it is.
Post #5 is the version of this I will quote in future. One addition.
Maintaining a calculator means checking the arithmetic against hand-worked cases at each review, not checking that it still loads.
That distinction has done more work for me than anything else in this category.
Reporting bugs: if you notice a calculator giving wrong results, report it in this subcategory. Bugs are fixed when identified.
Post #9 answers the question as asked. The question underneath it is different.
Nothing a calculator produces is medical advice, and a correct calculation on inappropriate inputs is still an inappropriate answer.
Do the arithmetic by hand the first few times, whatever tool you use afterwards. A calculator with a wrong input gives a confident wrong answer and there is nothing in the interface to tell you.
Flagging that the sources on this are thinner than the confidence in the thread suggests.
Post #11 answers the question as asked. The question underneath it is different.
On calculator, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.
If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.
I read post #13 twice before replying, because I had assumed the opposite.
Two claims get bundled together under calculator 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 follows post #14 rather than contradicting it.
Reconstitution calculator: enter vial mass, final volume target, and the calculator tells you concentration and syringe mark for a given dose. Useful for double-checking arithmetic when you are doing it by hand.
A calculator that shows its working is worth ten that give an answer. The whole value is being able to see which step you disagree with.
I would rather be precise about what I do not know than vague about what I do.
Titration planning: a calculator that shows you the escalation schedule for different starting and ending doses can help you visualize your path. Actual path might be slower or adjusted for tolerability.
Coming back to post #16, because the follow-up matters more than the original answer.
Calculator has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.
A request rather than an answer: could whoever has the primary source for calculator post it? I have seen the claim three times this month and each version had lost a qualifier.
On post #16 — agreed on the reasoning, with one qualification.
Where a calculator and your own arithmetic disagree, the productive move is to find which step differs rather than to decide which is right.
Confirming post #21 from a second method, which matters more than confirming it from a second person.
Two things can be true about calculator at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.
Post #21 describes the usual case. This is about the unusual one.
Dead volume is the input most calculators do not have, which is why their answer and the delivered dose differ slightly for detachable-needle configurations.
It is one reading of the data and not the only reasonable one.
The residual-volume question belongs in the tool rather than in a footnote, because it is the difference between the calculation and reality.
The literature is thinner on this than the confidence in the thread implies.
This is the first time the answer has come with its own limits attached. Appreciated.
Post #24 is right about the mechanism and I think understates the practical bit.
Dose equivalence calculator: compounds have different potencies. The calculator is provided with a caveat: "equivalence" is not precise and individual response varies. It is a rough starting point, not a dose prescription.
One of those cases where knowing the mechanism does not help the decision.
Precision and significant figures: the calculators do not round to match your input precision. If you input values to one decimal place, the output might have more. Use significant figures appropriate to your input precision.
I would treat that as a working assumption and revisit it.
Dead volume is the input most calculators do not have, which is why their answer and the delivered dose differ slightly for detachable-needle configurations.
On balance I think that is right, and I would not bet much on it.
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