help me understand dead space, I have read the wiki twice
Trying to get a straight answer on this: help me understand dead space, I have read the wiki twice.
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.
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.
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.
Not medical advice, obviously, and nothing here is approved for human use. One person with a spreadsheet.
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.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
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Reconstituted at 3mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 6.67mg/mL on the glass before I put the cap back.
Asked WWB 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.
Reminder: this board does maths, not dosing. Nobody here tells another member what amount to take.
Spent 17 weeks confused about this until somebody drew the table for me. 5mg, 2mL, 2.5mg/mL, 0.75mg is 30 units. That is the whole thing.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
That is sterile water, not bacteriostatic.
Right, and the arithmetic behind it: 10mg in 2mL is 5mg/mL, so 1mg is 20 units.
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.
Adding more water does not change how much peptide is in the vial.
Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.
- 1Started reconstituting everything to a round concentration and the…7 comments in this branch · started by u/vito_beaulieu