insulin syringe is the most under-discussed thing on this board
insulin syringe is the most under-discussed thing on this board. Making the case below, and I expect to lose some of it in the comments. 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. Adding…
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.
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.
Spent 20 weeks confused about this until somebody drew the table for me. 20mg, 1mL, 20mg/mL, 2mg is 10 units. That is the whole thing.
if the maths gives you a fraction of a unit, change the concentration
label the vial with the date as well as the concentration
Correction: that gives 20 units, not what you have written. 5mg into 1mL is 5mg/mL and the division follows from there.
I would not round that figure. At 1.67mg/mL a rounding error of two units is a real fraction of the intended amount.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
Research-use-only material is not approved for human use, so treat everything in this thread as arithmetic about solutions rather than instructions for a person.
Is that a U-100 syringe? The barrel markings change the answer completely.
dead space in the needle hub is real and it is small