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

how much of what we believe about mg/mL actually comes from insulin syringe threads

PSAbranch of 8 comments

how much of what we believe about mg/mL actually comes from insulin syringe threads, and I want the answer with the reasoning attached rather than just the conclusion. 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…

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8 comments, started 2 months ago
u/priya_weiss42 points·2 months ago

bacteriostatic water has the preservative, sterile water does not

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u/karim_ilunga15 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/vial_math_verasyringe math10 points·2 months ago

That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.

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u/saskia_mwangi0 points·2 months ago

What is written on the vial right now?

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u/marta_weiss1 point·2 months ago

Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.

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u/rina_bergstrom13 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/georgi_adebayo3 points·2 months ago

Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.

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u/arne_restrepo2 points·2 months ago

aim the stream at the glass wall, not at the cake

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About c/reconstitution

The arithmetic and the technique. Bacteriostatic versus sterile water, reconstitution volume as a concentration choice, converting mg/mL into insulin-syringe units, dead space, swirl-not-shake, stopper coring, and how long a reconstituted vial is actually good for. Math errors get corrected fast and politely.

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