[Question] how do you actually verify insulin syringe
Asking properly rather than in a comment on somebody else’s thread: how do you actually verify insulin syringe.
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.
Not medical advice, obviously, and nothing here is approved for human use. One person with a spreadsheet.
best — the order this archive was captured in
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.
Agreed on the swirl. There is no reason to shake it and a good reason not to.
Correction: that gives 15 units, not what you have written. 10mg into 3mL is 3.33mg/mL and the division follows from there.
Correction: that gives 15 units, not what you have written.
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.
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
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.
Careful — that arithmetic is wrong. 5mg in 3mL is 1.67mg/mL, so 0.25mg draws to 15 units, not what you wrote.
Asked CPC what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
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 arithmetic in full: concentration is mass over volume, so 20mg into 2mL gives 10mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 2.5mg is 2.5 divided by 10 millilitres, which is 25 units.
Spent 24 weeks confused about this until somebody drew the table for me. 10mg, 2mL, 5mg/mL, 0.75mg is 15 units. That is the whole thing.
Reconstituted at 3mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 10mg/mL on the glass before I put the cap back.
This. Showing the working is the fastest way for somebody else to spot the mistake.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
I keep a laminated card in the drawer with the arithmetic on it.
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
Is that a U-100 syringe? The barrel markings change the answer completely.
Adding more water does not change how much peptide is in the vial. It changes the concentration, which changes the volume you draw for the same amount. That is the entire relationship.
Are you accounting for the powder volume, or is that where the confusion is?
I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.
the powder cake sits at the bottom, the volume you add is the volume that counts
if the maths gives you a fraction of a unit, change the concentration
- 1Careful — that arithmetic is wrong. 5mg in 3mL is 1.67mg/mL, so 0.25mg draws…10 comments in this branch · started by u/clara_weiss