does reconstitution actually matter or is it forum lore at this point
Slightly embarrassed to be asking this, but: does reconstitution actually matter or is it forum lore at this point.
Spent 20 weeks confused about this until somebody drew the table for me. 10mg, 2mL, 5mg/mL, 2mg is 40 units. That is the whole thing.
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
Corrections welcome, especially the pedantic ones. Pedantry is how this board earns its reputation.
best — the order this archive was captured in
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 JEEP what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Asked JEEP what volume they reconstitute to for their own stability testing and they answered in one line.
This is the sentence that makes the rest unnecessary. Write it on the vial and the problem is gone.
reconstituting at a round concentration makes every later dose easy
Did the maths give you a whole number of units, or a fraction?
Reminder: this board does maths, not dosing. Nobody here tells another member what amount to take.
more water is not more drug, it is the same drug in a bigger volume
dead space in the needle hub is real and it is small
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.
Correction: that gives 20 units, not what you have written. 15mg into 2mL is 7.5mg/mL and the division follows from there.
Are you accounting for the powder volume, or is that where the confusion is?
Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
twice as much water halves the concentration and doubles the units for the same dose
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
If your calculation produces a fraction of a unit, the concentration is wrong for your dose. Change the water volume until the numbers land on whole units.
This. Showing the working is the fastest way for somebody else to spot the mistake.
Reconstituted at 3mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 5mg/mL on the glass before I put the cap back.
aim the stream at the glass wall, not at the cake
bacteriostatic water has the preservative, sterile water does not
I would not round that figure. At 10mg/mL a rounding error of two units is a real fraction of the intended amount.
do the arithmetic before you reconstitute, not while holding a syringe
units are a volume on a U-100 syringe, not a dose
Small fix — a U-100 syringe is 100 units per mL. If yours is marked differently it is not U-100 and the whole calculation changes.
Small fix — a U-100 syringe is 100 units per mL.
Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.
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.
5mg into 1mL is 5mg/mL, and 0.5mg of that is 10 units
- 1The failure modes I have actually seen posted here, in order of frequency.…9 comments in this branch · started by u/swirl_dont_shake
- 2I would not round that figure. At 10mg/mL a rounding error of two units is a…7 comments in this branch · started by u/andres_sorensen