[PSA] your bac water is fine, your fridge door is not
your bac water is fine, your fridge door is not. That is the post. The justification is underneath.
Asked SGN what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
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.
I will update this if the picture changes rather than quietly leaving it up.
best — the order this archive was captured in
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.
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.
If your calculation produces a fraction of a unit, the concentration is wrong for your dose.
Right, and the arithmetic behind it: 5mg in 1mL is 5mg/mL, so 5mg is 100 units.
Research-use-only material is not approved for human use, so treat everything in this thread as arithmetic about solutions rather than instructions fo
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
soren_zamora has the units point exactly right. They are a volume on the barrel and nothing else.
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.
Careful — that arithmetic is wrong. 15mg in 2mL is 7.5mg/mL, so 0.75mg draws to 10 units, not what you wrote.
10mg into 3mL is 3.33mg/mL, and 2.5mg of that is 75 units
The arithmetic in full: concentration is mass over volume, so 15mg into 1mL gives 15mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 0.75mg is 0.75 divided by 15 millilitres, which is 5 units.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Agreed on the swirl. There is no reason to shake it and a good reason not to.
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.
I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.
I keep a laminated card in the drawer with the arithmetic on it.
Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.
Adding one thing — put the date on the label too.
This is the sentence that makes the rest unnecessary. Write it on the vial and the problem is gone.
a U-100 syringe reads 100 units to the millilitre, every time
aim the stream at the glass wall, not at the cake
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
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reconstituting at a round concentration makes every later dose easy
more water is not more drug, it is the same drug in a bigger volume
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
if the maths gives you a fraction of a unit, change the concentration
do the arithmetic before you reconstitute, not while holding a syringe
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.
Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.
- 1The arithmetic in full: concentration is mass over volume, so 15mg into 1mL…9 comments in this branch · started by u/viktor_erdogan
- 2Research-use-only material is not approved for human use, so treat…7 comments in this branch · started by u/yusuf_achebe