[Meta] the mg/mL rule is doing its job and people should stop complaining
the mg/mL rule is doing its job and people should stop complaining. Short post, long comment section, probably. Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero. The whole calculation, once, with real numbers. You have a 10mg vial. You add 3mL of…
do the arithmetic before you reconstitute, not while holding a syringe
The lyophilised cake displaces a small volume, so the true concentration is very slightly lower than the arithmetic suggests. It is a fraction of a percent and it is dwarfed by fill tolerance.
The lyophilised cake displaces a small volume, so the true concentration is very slightly lower than the arithmetic suggests.
This is the sentence that makes the rest unnecessary. Write it on the vial and the problem is gone.
Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.
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The dead space question sent me down a rabbit hole for a week. It is a fraction of a unit and it is the same every draw.