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c/reconstitution·posted 19 days ago by u/signe_grimaldi

reconstituted at 1mL instead of 2mL and caught it before injecting. lucky.

Math Slow Clap ×7 Sourced ×3

Genuinely asking, not being difficult.

Everyone in c/cagrilintide repeats that dead space is important. I believe it, but I have never seen anyone show why, and when I search I get 9 threads of people agreeing with each other.

Is there a paper? Is there a measurement? Or is this one of those things that is true because it has been repeated since 2023?

I am not trying to be the "source?" guy. I would just like a source.

2,181 up / 119 down95% upvoted51 commentsid 18uete11 Jul 2026

51 comments

30 in this archive, depth 5

best — the order this archive was captured in

u/andres_sorensen268 points·18 days ago

I love that this community will spend 40 comments on a detail. That pedantry is why the numbers here matter.

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u/signe_grimaldiOP104 points·17 days ago

I am going to push back on this slightly.

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u/vial_math_veraMOD135 points·17 days ago

Retitled to remove editorialising. Put the evidence in the body.

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u/georgi_adebayo134 points·17 days ago

This is correct. 1mL versus 4mL is the common mistake.

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u/ledger_modmod · vetting44 points·17 days ago

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

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u/piotr_bruun19 points·17 days ago

What was the vial size and how much bac water?

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u/sleep_apnea_sam137 points·17 days 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/andres_sorensen41 points·17 days ago

Disagree. What you are describing is consistent with concentration, not with what you concluded.

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u/emil_okwuosa31 points·17 days ago

never post a calculation as advice without stating the concentration

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u/signe_grimaldiOP21 points·17 days ago

swirl, do not shake, or you are courting oxidation

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u/hedda_adeyemi6 points·17 days ago

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

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u/signe_grimaldiOP-21 points·17 days ago

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

Yes, exactly this, and it is the bit that took me 7 weeks to accept.

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u/mateusz_achebe69 points·17 days ago

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

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u/saskia_mwangi38 points·16 days 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/viktor_erdogan14 points·16 days ago

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

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u/emil_wojcik4 points·16 days ago

dead space is real and the syringe matters

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u/quiet_reader_9931 points·16 days ago·edited

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

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u/tl_dr_tina18 points·16 days 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/karim_ilunga52 points·16 days ago

stopper coring on the 3th draw because you keep using the same entry point. rotate.

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u/rosa_mensah28 points·16 days ago

stopper coring on the 3th draw because you keep using the same entry point.

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

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u/adaeze_cabrera65 points·17 days ago

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

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u/swirl_dont_shakereconstitution27 points·16 days ago

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

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u/yusuf_nakamura69 points·17 days ago

Is that 30mg vial or 24mg?

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u/marisol_frisk31 points·17 days ago

Dead space ate 3 units on a low-volume draw. Tiny impact at 1.0mg, massive impact at 0.5mg.

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u/vito_beaulieu18 points·17 days ago

show your working or it is unhelpful

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u/emeka_delgado49 points·18 days ago

Titration speed is a side-effect dial far more than an efficacy dial.

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[removed]37 points·18 days ago

[removed by moderator]

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u/RetaAndRegret221 points·17 days ago

I am going to push back on this slightly.

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u/viktor_erdogan16 points·17 days ago

stopper coring on the 10th draw because you keep using the same entry point. rotate.

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u/freya_onwuka11 points·17 days ago

never post a calculation as advice without stating 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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