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

reconstitution: what the trials say vs what this community says

Discussion Slow Clap ×7 Sourced ×3 Clean Column ×2

Right, the concentration question again, but with numbers this time.

I have 13 data points over 32 weeks. The pattern is consistent enough that I do not think it is chance, and boring enough that nobody is going to screenshot it, which is usually a good sign.

The thing I would flag for anyone new: the effect I am describing showed up at week 36, not week 85. People give up long before the interesting part.

Interested in whether this matches other people's logs or whether I am an outlier.

32,323 up / 23,951 down57% upvoted38 commentsid gpiuf98 Mar 2024

38 comments

22 in this archive, depth 5

best — the order this archive was captured in

u/RetaAndRegret2929 points·2 years ago

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

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u/viktor_kirchner773 points·2 years ago

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

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u/clara_weiss520 points·2 years ago

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

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u/erez_perrin366 points·2 years ago

Dead space in the needle hub holds a small but non-trivial volume. On low-volume draws that can be several units.

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u/hedda_adeyemi306 points·2 years ago·edited

Half-life is about 168 hours, so steady state lands around week 14–5. Practical consequence: what you feel in week 1 is not what that dose does.

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u/soren_zamora213 points·2 years ago

5mg vial, 2mL water, concentration is 5/2 — write it on the vial afterwards

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u/oskar_kaufmann74 points·2 years ago

Half-life is about 168 hours, so steady state lands around week 14–5.

Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.

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u/hedda_ekstrom289 points·2 years ago

This is correct. 3mL versus 14mL is the common mistake.

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u/aurel_boateng233 points·2 years ago

Show the arithmetic. Where did the units come from?

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u/priya_guerrero66 points·2 years ago

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

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u/ismael_nwosu158 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/vial_math_veraOPsyringe math109 points·2 years ago

show your working or it is unhelpful

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u/lurker_for_years123 points·2 years ago

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

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u/elin_ferrari147 points·2 years ago

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

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u/kenji_kimani49 points·2 years ago

Rodent data is rodent data. Dose scaling is not linear and the models tell you what to investigate, not what to expect.

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u/katrin_marchetti74 points·2 years ago

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

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u/vito_beaulieu107 points·2 years ago

i am begging people to write down the concentration

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u/katrin_marchetti83 points·2 years ago

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

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u/bruno_dumitru75 points·2 years ago

Crossposting this to c/cagrilintide because the people who need it are not reading this community.

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u/anya_antonsen-2 points·2 years ago

u-100 syringe, not u-40, or your math is off by factor of 10

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u/runa_grimaldi65 points·2 years ago

Every time this gets posted it hits the front page and every time someone has to re-explain it.

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u/dilara_szabo38 points·2 years ago

This is correct. 1mL versus 2mL is the common mistake.

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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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