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c/reconstitution·posted 2 years ago by u/marta_weiss

the dead space question that gets asked weekly, answered properly

PSA Receipts ×3 Cold Box ×1 Long Haul ×1

Trying to settle this properly because the thread from last year went in circles.

The claim: reconstitution matters. The counter-claim: it is measurement error. Both sides have been asserting it confidently for about 9 months without either producing anything.

What would actually settle it is 27 people measuring the same thing the same way. I have started; my numbers are below. They lean one way but not strongly enough for me to declare victory.

If you have data, post the data. If you have an opinion, flair it as an opinion.

9,242 up / 1,984 down82% upvoted54 commentsid gzig4824 Jan 2024

54 comments

21 in this archive, depth 5

best — the order this archive was captured in

u/a1c_arcT2D803 points·2 years ago

Reconstituted at 3mL when I meant 7mL. Caught it because the units looked wrong. Write the concentration.

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u/viktor_kirchner338 points·2 years ago

dead space is real and the syringe matters

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u/janek_ferrari642 points·2 years ago

never post a calculation as advice without stating the concentration

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[deleted]467 points·2 years ago

[deleted]

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u/sleep_apnea_sam677 points·2 years ago

u-100 syringe, not u-40, or your math is off by factor of 7

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u/vito_beaulieu562 points·2 years ago

the concentration on the vial in marker is the most important step

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u/marta_weissOP285 points·2 years ago

30mg vial, 2mL water, concentration is 30/2 — write it on the vial afterwards

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u/karl_fischer_kev158 points·2 years ago

Sceptical. If this were true we would see it reflected in the data and we do not.

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u/swirl_dont_shakereconstitution515 points·2 years ago
yep. 30 weeks in, same.
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u/cesar_ivaturi171 points·2 years ago

Are you using a u-100 or u-40 syringe? That changes everything.

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u/marta_weissOP64 points·2 years ago

dosing errors come from people reconstituting two vials differently and forgetting which is which

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u/britta_nakamura-16 points·2 years ago

Not convinced. The evidence does not support that reading.

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u/dilara_szabo1 point·2 years ago

Cosigning. The concentration on the vial in marker is load-bearing.

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u/nabila_espinoza1 point·2 years ago

Show the arithmetic. Where did the units come from?

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u/runa_cabrera1 point·2 years ago

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

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u/ismael_nwosu1 point·2 years ago

Slight fix: the number was 98.1, not 98.0. Decimal point, but a fairly consequential one.

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u/marta_weissOP1 point·2 years ago

This is correct. 2mL versus 6mL is the common mistake.

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u/katrin_marchetti1 point·2 years ago

Are you using a u-100 or u-40 syringe? That changes everything.

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u/alcohol_aversion1 point·2 years ago

dead space is real and the syringe matters

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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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