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Single comment threadYou are looking at one branch of three years of bacteriostatic water threads, summarised so you do not have to read them — 29 comments in the full submission. View in context.
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c/reconstitution·submitted 2 years ago by u/lurker_for_years

three years of bacteriostatic water threads, summarised so you do not have to read them

Explainerbranch of 8 comments

three years of bacteriostatic water threads, summarised so you do not have to read them. Making the case below, and I expect to lose some of it in the comments. Asked KP what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know. Started reconstituting…

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8 comments, started 2 years ago
u/vial_math_verasyringe math133 points·2 years ago

Careful — that arithmetic is wrong. 20mg in 2mL is 10mg/mL, so 1mg draws to 10 units, not what you wrote.

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u/oskar_ibarra43 points·2 years ago·edited

Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.

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u/cesar_ivaturi55 points·2 years ago

swirl, never shake

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u/lurker_for_yearsOP32 points·2 years ago

30mg into 3mL is 10mg/mL, and 1.5mg of that is 15 units

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u/rasmus_kuipers13 points·2 years ago·edited

Is that a U-100 syringe? The barrel markings change the answer completely.

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u/viktor_erdogan4 points·2 years ago·edited

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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[removed]30 points·2 years ago

[removed by moderator]

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u/sock_puppet_spotter-19 points·2 years ago

label the vial with the date as well as the concentration

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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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