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c/reconstitution·posted 10 months ago by u/aurel_boateng

why does nobody talk about dead space

Correction Clean Column ×6 Receipts ×2 Slow Clap ×1

dead space. That is the whole post, but I will justify it.

Everything else people worry about in c/intlshipping is downstream of it. Titration speed, reflux, the endless dose arguments — most of it resolves if you sort dead space out first, and almost nobody does.

I say this having got it wrong for 2 months. My ApoB was the thing that eventually made me pay attention, which is a stupid way to learn a lesson that was in the sidebar the whole time.

7,905 up / 3,044 down72% upvoted47 commentsid 18jx8m22 Sep 2025

47 comments

30 in this archive, depth 5

best — the order this archive was captured in

u/units_not_mgsyringe math599 points·10 months ago

This is correct. 2mL versus 4mL is the common mistake.

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u/emil_okwuosa881 points·10 months ago

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

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u/tuva_kirchner452 points·10 months ago

Cored the stopper on my 6th draw because I kept using the same entry point. Rotate the puncture site.

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u/vial_math_veraMOD234 points·10 months ago·edited

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

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u/batch_number_bertievetting195 points·10 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/priya_weiss122 points·10 months ago

Show the arithmetic. Where did the units come from?

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u/emil_okwuosa306 points·10 months 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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[removed]227 points·10 months ago

[removed by moderator]

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u/quarter_dose_queenlow and slow75 points·10 months ago

i am begging people to write down the concentration

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u/aurel_boatengOP100 points·10 months ago

What was the vial size and how much bac water?

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u/hedda_adeyemi176 points·10 months ago

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

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u/ledger_modmod · vetting134 points·10 months ago

Is that 30mg vial or 17mg?

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u/aurel_boatengOP139 points·10 months ago

Two vials, two different concentrations, forgot which was which, almost made a 7 times error. Now I label everything.

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u/oskar_kaufmann245 points·10 months ago

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

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u/signe_grimaldi169 points·10 months ago

What was the vial size and how much bac water?

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u/bac_water_banditreconstitution-38 points·10 months ago

show your working or it is unhelpful

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u/cesar_ivaturi80 points·10 months 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/anya_antonsen303 points·10 months ago

more water means more units for the same dose, which means finer resolution

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u/julia_erdogan161 points·10 months ago

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

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u/hedda_ekstrom126 points·10 months ago

u-100 syringe, not u-40, or your math is off by factor of 15

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u/ismael_nwosu131 points·10 months ago

Show the arithmetic. Where did the units come from?

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u/dexa_twice_yearlybody comp41 points·10 months ago

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

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u/sigrid_kaufmann227 points·10 months 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_shakereconstitution187 points·10 months ago·edited

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

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u/soren_zamora50 points·10 months ago

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

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u/karim_ilunga27 points·10 months ago

show your working or it is unhelpful

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u/rasmus_kuipers167 points·10 months ago

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

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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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