how much of what we believe about reconstitution actually comes from concentration threads
how much of what we believe about reconstitution actually comes from concentration threads. If this has been answered properly somewhere, link me and I will delete.
The failure modes I have actually seen posted here, in order of frequency.
One: reconstituting at a different volume than intended and not writing it down, so the next draw is based on a remembered concentration. Two: treating units as a dose rather than a volume, which breaks the moment the concentration changes. Three: assuming a syringe is U-100 when it is not.
All three are solved by the same two habits — do the arithmetic before the water goes in, and write the result on the glass. Neither costs anything and between them they cover almost every question this board gets.
Asked SGN what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Bacteriostatic water contains benzyl alcohol as a preservative, which is what makes repeated entry into the same vial reasonable. Plain sterile water has no preservative.
If somebody has the same thing measured a different way, post it next to mine and we will see whether they agree.
best — the order this archive was captured in
Why "more water" keeps confusing people, including me for a month.
The vial contains a fixed amount of peptide. Water changes nothing about that amount. What it changes is concentration, and concentration is the divisor between the dose you want and the volume you draw.
So doubling the water halves the concentration and doubles the units for the same dose. Nothing is diluted in any sense that matters; you are simply reading a bigger number off the same barrel. Pick the water volume that puts your usual dose on a whole number of units and life gets easier.
Reconstituted at 3mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 6.67mg/mL on the glass before I put the cap back.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
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Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.
How many mg in the vial and how many mL are you adding?
if the maths gives you a fraction of a unit, change the concentration
more water is not more drug, it is the same drug in a bigger volume
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
What concentration did you actually reconstitute at, rather than what did you intend to?
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.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
Yes. Writing 5mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
- 1Not quite. Bacteriostatic and sterile water are not interchangeable for a…7 comments in this branch · started by u/janek_ferrari