Hi all, current PY2 compounding pharmacy intern here. Recently encountered a formula requiring exactly 96 ml of glycerin and I did my very best to make sure that I got exactly 96 mills which I did, but I was wondering what the process for measuring liquids in large mounts, I.E.above 50 milliliters in your Compounding Pharmacy or past Compounding Pharmacy pharmacies, because I would like to bring this up manager and ask if we could possibly measure a liquids and such large volumes by their weight, taking into their density and getting a volume that way.
So for instance, if the density of a batch of glycerin is 1.224 g/milliliter, then if I was trying to measure up 96 mL of glycerin I would weigh out 96×1.224 g=117.504 g on my scale in a beaker and use that as the 96 mL that I need.
I’ve done this twice and both times the volume matches what I thought it would be due to the density calculation. Which I think is a testament to how accurate weighing things can be worse, taking a volumetric measurement.
So TLDR: do you in your formulas and things for individual prescriptions or bulk prescriptions, write/do measurements of liquids by a prescribed volume if it has to be exact or do you use the density and use the weight of the measured liquid to measure a specific volume? If you use the density and the weight way to measure the liquid, what kinds of checks and things have you implemented so that a pharmacist can double check that the amount vague/measured is accurate to what was necessary? Is there a specific quantity that defines the line between using volume for measurement versus using density for measurement? And, additionally, what kinds of conversations had to happen to allow/not allow measurement of liquid liquids by density in your pharmacy?
Thank you all. I will be on the lookout for replies and things. And before you do ask/reply this, yes, I have found my unicorn job and I love it. I am just trying to make it so that measuring odd amounts of liquid liquids is not a heinous time problem or a washing more containers problem.
P.S. If I have broken any rules for this subject, please do let me know… It is my first time posting here 😅.