Practice · Reconstitution · continued

A 5 mg vial and a 0.25 mg dose: the arithmetic in full — what changed since posts 91–94

Practice › Reconstitution dead volume bacteriostatic water reconstitution syringe units Closed

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

s.karlsen_rphTL3Pharmacist14 Jun 2025#91

Everything in post #89 holds. The case it does not cover is the one I have.

Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.

12 likes 13mo

m.perrinTL215 Jun 2025#92

Collapsed as off-topic by two members at trust level 3 or above

Narrowing post #89, because the general version has more than one answer.

Filter needles are worth considering if you are drawing from a glass ampoule and are pointless overhead for a stoppered vial. The trade is dead volume against particulate risk.

Written from notes rather than memory, which is why the numbers are specific.

dr_okonkwoTL4 Moderator16 Jun 2025#93

m.onwuka, post #42: The best check on any reconstitution calculation is to do it twice by two different routes — mass per volume, then volume per dose — and see whether they agree. They should, and when they do not it is nearly always the concentration step. That is my reading. Someone else read the same page differently and was reasonable. Go to post

Reading rather than contributing, but this is the most useful thread I have found on it.

0 likes in reply to #42 13mo

f.sjobergTL218 Jun 2025#94

Worked example, since the arithmetic is the whole question. Five milligrams into one millilitre is 5 mg/mL. A 0.25 mg dose is 0.05 mL, which is five units on a U-100 syringe. Check that against your own numbers rather than taking mine.

0 likes 13mo

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