Weighing in on gravimetrics

I’ve been doing a lot of research lately on i.v. workflow management system. In fact, I’ve been able to spend time observing several of these systems in operation in real healthcare facilities. If you really want to see how something works in a pharmacy spend some time watching a technician work and talking to them about it. You can only learn so much from marketing material, which is, shall we say, less than completely forthcoming with information.

Each system I’ve reviewed has fundamentally the same concept, but different approaches. One of the most distinct differences I’ve encountered is the inclusion or exclusion of gravimetric analysis during the i.v. compounding process. Some have it, some don’t.

For those that don’t know, the gravimetric process basically utilizes the known specific gravity of a solution to quantitatively determine the analyte, i.e. the drug found in the solution. In the case of an i.v. preparation, the method can be used to determine the accuracy of a dose drawn into a syringe, removed from a vial, injected into an i.v. bag, and so on. The assumption here is that if you know the weight of an object – syringe, i.v. bag, vial of medication, etc – before and after adding or removing a substance, then you know exactly how much drug was added or removed. It’s a concept I remember from my analytical chemistry days as an undergraduate chemistry major. Is it accurate? When performed properly it’s extremely accurate.

Some people consider the idea of using gravimetric analysis during the i.v. compounding process to be of the utmost importance. I’m not convinced. I view the addition of gravimetrics to a product to be a nice feature, but certainly not a necessity. Perhaps for high risk medications, or in the case of minute liquid volumes gravimetric analysis would make more sense, but not for general i.v. compounding. Volumetric measurement, i.e. the use of a syringe to measure a liquid is ample for a vast majoring of routine i.v. preparation.

Most systems already utilize a combination of bar code scanning and image capture to provide data suitable for preparation verification. I’m skeptical that the addition of gravimetric analysis adds much value to the process. I certainly do not believe that gravimetric analysis should replace bar code scanning or image capture during the compounding process.

There are of course those that would say using gravimetrics in addition to bar code scanning and image capture is the way to go, and it would be hard to argue against that premise with any real fervor, but to add the additional steps to an already laborious process just doesn’t seem logical to me.

However, this is simply one man’s opinion. Take it for what it’s worth.

2 thoughts on “Weighing in on gravimetrics”

  1. Got to say I agree with you 100% DoseEdge has it advantages here but it is already very very time consuming I couldnt imagine adding in gravimetric analysis I enjoyed your article and look forward to reading more
    Danny Chaney Cpht Lawrence and Memorial hospital in New London CT

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