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c/reconstitution·submitted 3 days ago by u/katrin_marchetti

[PSA] your bac water is fine, your fridge door is not

PSAbranch of 9 comments

your bac water is fine, your fridge door is not. That is the post. The justification is underneath. Asked SGN 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…

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9 comments, started 1 days ago
u/viktor_erdogan36 points·1 days ago

The arithmetic in full: concentration is mass over volume, so 15mg into 1mL gives 15mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 0.75mg is 0.75 divided by 15 millilitres, which is 5 units.

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u/katrin_marchettiOP16 points·1 days ago

I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.

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u/clara_weiss8 points·1 days ago

Agreed on the swirl. There is no reason to shake it and a good reason not to.

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u/ines_ekstrom2 points·23 hr ago

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.

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u/quarter_dose_queenlow and slow2 points·21 hr ago

I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.

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u/a1c_arcT2D5 points·1 days ago

I keep a laminated card in the drawer with the arithmetic on it.

Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.

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u/ismael_nwosu0 points·16 hr ago

Adding one thing — put the date on the label too.

This is the sentence that makes the rest unnecessary. Write it on the vial and the problem is gone.

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u/hedda_ekstrom2 points·1 days ago

a U-100 syringe reads 100 units to the millilitre, every time

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u/ahmed_rasmussen1 point·20 hr 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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