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c/reconstitution·posted 1 months ago by u/a1c_arc

[Discussion] mg/mL is doing more work than we give it credit for

Discussion Sourced ×2

Genuinely asking, not being difficult.

Everyone in c/cagrilintide repeats that concentration is important. I believe it, but I have never seen anyone show why, and when I search I get 13 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.

6,424 up / 5,593 down53% upvoted31 commentsid 15sg1a23 Jun 2026

31 comments

24 in this archive, depth 4

best — the order this archive was captured in

u/anjali_tamm143 points·1 months ago

This is correct. 1mL versus 23mL is the common mistake.

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u/emil_wojcik0 points·1 months ago

stopper coring on the 6th draw because you keep using the same entry point. rotate.

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u/a1c_arcOPT2D-28 points·1 months ago

Reconstituted at 2mL when I meant 22mL. Caught it because the units looked wrong. Write the concentration.

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u/escrow_evangelist100 points·1 months ago

Did you write the concentration on the vial?

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u/a1c_arcOPT2D74 points·1 months ago

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

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u/a1c_arcOPT2D38 points·1 months ago

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

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u/aleksi_lehtinen53 points·1 months ago

Reconstituted at 1mL when I meant 23mL. Caught it because the units looked wrong. Write the concentration.

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u/bac_water_banditreconstitution23 points·1 months ago

Not to be pedantic but concentration and insulin syringe are being used interchangeably and they are not interchangeable in real life.

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u/andres_sorensen15 points·1 months ago

That is net peptide content, not purity. Different number, different meaning.

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u/cesar_ivaturi36 points·1 months ago

What was the vial size and how much bac water?

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u/karl_fischer_kev29 points·1 months ago

i am begging people to write down the concentration

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u/sofia_danquah14 points·1 months ago

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

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u/sock_puppet_spotter13 points·1 months ago

u-100 syringe, not u-40, or your math is off by factor of 19

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u/reflux_report46 points·1 months ago

Dead space ate 24 units on a low-volume draw. Tiny impact at 1.7mg, massive impact at 0.25mg.

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u/rina_bergstrom24 points·1 months ago

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

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u/emil_okwuosa19 points·1 months ago

Dead space ate 12 units on a low-volume draw. Tiny impact at 5mg, massive impact at 2.5mg.

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u/swirl_dont_shakeMOD19 points·1 months ago

Removed a chain here. The rule is one line long and it is not negotiable.

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u/saskia_mwangi13 points·1 months ago

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

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u/emil_okwuosa25 points·1 months ago

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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u/saskia_mwangi12 points·1 months ago

dead space is real and the syringe matters

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u/marta_weiss5 points·1 months ago

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

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u/india_generic_g7 points·1 months ago

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

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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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