[Meta] proposal — a flair for mg/mL posts
proposal — a flair for mg/mL posts — posting the reasoning in public because a policy you cannot inspect is just a preference.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
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.
Ask me anything specific. Anything general I will probably get wrong.
best — the order this archive was captured in
Aim the stream down the wall of the vial rather than into the cake. Reconstitution is a solubility problem, not a mixing problem, and mechanical shear does nothing helpful.
How many mg in the vial and how many mL are you adding?
aim the stream at the glass wall, not at the cake
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
The arithmetic in full: concentration is mass over volume, so 5mg into 2mL gives 2.5mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 1mg is 1 divided by 2.5 millilitres, which is 40 units.
Asked HJ what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Spent 19 weeks confused about this until somebody drew the table for me. 5mg, 3mL, 1.67mg/mL, 1mg is 60 units. That is the whole thing.
Reminder: this board does maths, not dosing. Nobody here tells another member what amount to take.
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.
the number you write down is the number you will trust at 6am
Is that a U-100 syringe? The barrel markings change the answer completely.
a U-100 syringe reads 100 units to the millilitre, every time
the powder cake sits at the bottom, the volume you add is the volume that counts
What is written on the vial right now?