someone explain bacteriostatic water to me like I have not read a paper in years
someone explain bacteriostatic water to me like I have not read a paper in years. I am not trying to be the "source?" guy. I would just like a source.
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.
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.
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.
Sceptical readings welcome. The confident ones are the ones I distrust.
best — the order this archive was captured in
Agreed on the swirl. There is no reason to shake it and a good reason not to.
The arithmetic in full: concentration is mass over volume, so 10mg into 2mL gives 5mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 5mg is 5 divided by 5 millilitres, which is 100 units.
Left up and flaired Explainer — the numbers in this one check out.
Correction: that gives 30 units, not what you have written. 5mg into 1mL is 5mg/mL and the division follows from there.
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 is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
the powder cake sits at the bottom, the volume you add is the volume that counts
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
twice as much water halves the concentration and doubles the units for the same dose
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
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.
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
This. Showing the working is the fastest way for somebody else to spot the mistake.
- 1The arithmetic in full: concentration is mass over volume, so 10mg into 2mL…6 comments in this branch · started by u/saskia_rahimi