unpopular opinion: most of what gets said here about reconstitution is guesswork
unpopular opinion: most of what gets said here about reconstitution is guesswork — a position I have arrived at slowly and would like tested. 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…
I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.
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.
The arithmetic in full: concentration is mass over volume, so 5mg into 1mL gives 5mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 2mg is 2 divided by 5 millilitres, which is 40 units.
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.
dead space in the needle hub is real and it is small
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.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
Asked KP what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
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.
Did the maths give you a whole number of units, or a fraction?
reconstituting at a round concentration makes every later dose easy