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c/reconstitution·submitted 1 year ago by u/runa_grimaldi

someone explain mg/mL to me like I have not read a paper in years

PSAbranch of 11 comments

someone explain mg/mL to me like I have not read a paper in years. I am not trying to be the "source?" guy. I would just like a source. The lyophilised cake displaces a small volume, so the true concentration is very slightly lower than the arithmetic suggests. It is a fraction of a percent and it is dwarfed by fill…

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11 comments, started 1 year ago
u/honest_syringe_2025226 points·1 year ago

I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.

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u/bac_water_banditMOD116 points·1 year ago

Corrected the concentration in the title, which contradicted the body. Nothing else touched.

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u/sock_puppet_spotter53 points·1 year ago

write the concentration on the vial in marker, that is the whole post

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u/cesar_ivaturi156 points·1 year ago

reconstituting at a round concentration makes every later dose easy

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u/runa_grimaldiOP-5 points·1 year ago

Is that a U-100 syringe? The barrel markings change the answer completely.

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u/rasmus_kuipers47 points·1 year ago

more water is not more drug, it is the same drug in a bigger volume

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u/iman_falk14 points·1 year ago

swirl, never shake

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u/priya_weiss32 points·1 year ago

Small fix — a U-100 syringe is 100 units per mL. If yours is marked differently it is not U-100 and the whole calculation changes.

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u/ines_ekstrom102 points·1 year ago

Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.

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u/dilara_szabo62 points·1 year ago

Agreed — units are volume.

Right, and the arithmetic behind it: 15mg in 2mL is 7.5mg/mL, so 1.5mg is 20 units.

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u/honest_syringe_202583 points·1 year ago

Wrote the date on the vial as well as the concentration after losing track of which one was opened first.

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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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