why does nobody talk about units
The title is the whole question — why does nobody talk about units — but here is why I am asking.
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
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.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
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
Why "more water" keeps confusing people, including me for a month.
The vial contains a fixed amount of peptide. Water changes nothing about that amount. What it changes is concentration, and concentration is the divisor between the dose you want and the volume you draw.
So doubling the water halves the concentration and doubles the units for the same dose. Nothing is diluted in any sense that matters; you are simply reading a bigger number off the same barrel. Pick the water volume that puts your usual dose on a whole number of units and life gets easier.
Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.
Yes. Writing 10mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
I would not round that figure. At 10mg/mL a rounding error of two units is a real fraction of the intended amount.
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a U-100 syringe reads 100 units to the millilitre, every time
Correction: that gives 40 units, not what you have written. 5mg into 2mL is 2.5mg/mL and the division follows from there.
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.
aim the stream at the glass wall, not at the cake
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.
The arithmetic in full: concentration is mass over volume, so 20mg into 3mL gives 6.67mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 1mg is 1 divided by 6.67 millilitres, which is 15 units.
Bacteriostatic or plain sterile water?
Spent 20 weeks confused about this until somebody drew the table for me. 20mg, 3mL, 6.67mg/mL, 5mg is 75 units. That is the whole thing.
more water is not more drug, it is the same drug in a bigger volume
Corrected the concentration in the title, which contradicted the body. Nothing else touched.
Correcting myself above: I wrote the concentration the wrong way up. Mass over volume, not volume over mass.
Did the maths give you a whole number of units, or a fraction?
do the arithmetic before you reconstitute, not while holding a syringe
do the arithmetic before you reconstitute, not while holding a syringe
ines_ekstrom has the units point exactly right. They are a volume on the barrel and nothing else.
the number you write down is the number you will trust at 6am
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.
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
10mg into 2mL is 5mg/mL, and 0.5mg of that is 10 units
- 1do the arithmetic before you reconstitute, not while holding a syringe8 comments in this branch · started by u/ines_ekstrom
- 2Why "more water" keeps confusing people, including me for a month. The vial…7 comments in this branch · started by u/cardio_endpoint_c