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c/reconstitution·submitted 2 months ago by u/ilias_steiner

[Discussion] can we stop arguing about dead space until somebody posts a number

Discussionbranch of 6 comments

can we stop arguing about dead space until somebody posts a number. I would rather ask a basic question now than get this wrong quietly for two months. 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…

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6 comments, started 2 months ago
u/runa_cabrera17 points·2 months ago

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.

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u/saskia_rahimi5 points·2 months ago

Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.

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u/erez_perrin3 points·2 months ago

Correction: that gives 30 units, not what you have written. 20mg into 3mL is 6.67mg/mL and the division follows from there.

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u/iman_falk1 point·2 months ago

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.

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u/emil_zamora1 point·2 months ago

I would not round that figure. At 20mg/mL a rounding error of two units is a real fraction of the intended amount.

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u/honest_syringe_202513 points·2 months ago

Reconstituted at 2mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 2.5mg/mL on the glass before I put the cap back.

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