dead space — 16 things I got wrong before I got it right
dead space — 16 things I got wrong before I got it right. It is the sort of thing everyone half-believes and nobody writes down.
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Asked Homopeptide what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Spent 4 weeks confused about this until somebody drew the table for me. 10mg, 2mL, 5mg/mL, 2mg is 40 units. That is the whole thing.
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
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.
Yes. Writing 10mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
dead space in the needle hub is real and it is small
a U-100 syringe reads 100 units to the millilitre, every time
Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.
Correcting myself above: I wrote the concentration the wrong way up. Mass over volume, not volume over mass.
10mg into 1mL is 10mg/mL, and 2.5mg of that is 25 units
Correcting myself above: I wrote the concentration the wrong way up.
Right, and the arithmetic behind it: 5mg in 3mL is 1.67mg/mL, so 1.5mg is 90 units.
aim the stream at the glass wall, not at the cake
Show the arithmetic — where did the unit figure come from?
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
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.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
units are a volume on a U-100 syringe, not a dose
label the vial with the date as well as the concentration
twice as much water halves the concentration and doubles the units for the same dose
- 1aim the stream at the glass wall, not at the cake8 comments in this branch · started by u/britta_nakamura