The reconstitution guide is fairly emphatic about the order of operations. Is that real or is it tidiness?
Reconstitution: does the order of operations actually matter?
5 replies·
Real, and each step is there for a specific failure.
Let both vials reach room temperature first. Cold glass plus a temperature swing gets you condensation, and condensation on a stopper is water where you did not want water.
Swab both stoppers and let them dry. Covered elsewhere. Alcohol works while evaporating.
Aim the diluent at the glass wall, not at the cake. This is the one people get wrong. A jet of water fired directly into a lyophilised cake is mechanical stress on a fragile molecule. Down the wall, so it runs in.
Do not shake. Shaking generates foam, and foam is an enormous air-water interface. Proteins and peptides denature at interfaces — that is where the damage happens, not from the motion itself. Swirl gently, or leave it and come back.
Let it dissolve on its own. Most of a cake goes into solution without help if you give it a few minutes.
The through-line: peptides are damaged by shear and by interfaces, not by being handled slowly.
The foam explanation is the one that makes the rest make sense. I thought "do not shake" was superstition inherited from something else.
The one that actually catches people is the volume decision, because it is irreversible.
Once you have added the water, that is the concentration. You cannot go back. And people pick a round number for the water rather than a number that puts their intended volume in a readable part of the syringe.
Work out what you want to be measuring, then choose the diluent volume that makes that measurement land somewhere you can read. The calculator does the arithmetic; the decision is yours and it comes first.
And after it is in solution the clock has started — see the storage post. Dry powder is patient. Solution is not.
Sign in or create an account to reply.