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c/reconstitution·submitted 2 years ago by u/viktor_erdogan

the units question that gets asked weekly, answered properly

PSAbranch of 11 comments

Trying to settle this properly because the thread from last year went in circles. The claim: mg/mL matters. The counter-claim: it is measurement error. Both sides have been asserting it confidently for about 10 months without either producing anything. What would actually settle it is 33 people measuring the same…

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This branch

11 comments, started 2 years ago
u/emil_wojcik1.8k points·2 years ago

The single most useful thing I did was write the concentration on the vial. Stopped all the confusion after that.

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u/bac_water_banditreconstitution491 points·2 years ago

Show the arithmetic. Where did the units come from?

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u/vito_beaulieu719 points·2 years ago

bacteriostatic and sterile water are not interchangeable, do not use them that way

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u/marisol_frisk279 points·2 years ago

Small correction: the trial was 11 weeks, not 36. Does not change your point but people will quote it.

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u/erez_perrin144 points·2 years ago

dead space is real and the syringe matters

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u/anya_antonsen88 points·2 years ago

Edit to your parent would help — the concentration you quoted assumes one scenario and you have written another above it.

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u/erez_perrin0 points·2 years ago

swirl, do not shake, or you are courting oxidation

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u/bac_water_banditreconstitution113 points·2 years ago·edited

Small correction: the trial was 11 weeks, not 36.

Yes, exactly this, and it is the bit that took me 42 weeks to accept.

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u/santiago_ndiaye563 points·2 years ago

Yeah, showing the arithmetic is the fastest way for someone to spot the error.

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u/viktor_erdoganOP205 points·2 years ago

Slight fix: the number was 99.0, not 98.9. Decimal point, but a fairly consequential one.

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u/ines_ekstrom1.4k points·2 years ago

Show the arithmetic. Where did the units come from?

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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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