Written by Bryan Prince

Let’s discuss…

Recently I had a nice 45-minute conversation with a Certifier about a compounding pharmacy design project which led down the path of how certification of the primary engineering control (the hood) does not always align with workflow process in the compounding pharmacy,  This is more so with non-sterile powder environments, but I will circle back to that shortly.  My history in dealing with Certifiers goes back almost ten years when I was in the “containment” business.  Certifiers are the third party that come into your pharmacy to make sure the hoods, HEPA filters, and other engineering controls are operating correctly.  However, they do not truly understand every aspect of your compounding workflow and therein lies an issue.

Out of tune

When Certifiers show up at your pharmacy to certify the hoods they follow information published as manufacturer specifications and/or industry standards (e.g. ASHRAE, CFR, NSF, etc.) and/or industry guidelines (e.g. CETA -the certification industry organization).   I’m sure it is of no surprise that not all those pieces listed above are in perfect harmonization with each other.  Even with all those important reams of information the standards and/or guidelines can still conflict with your actual workflow process.  Therefore, the certifiers inadequately certify your facility’s hoods based on your specific needs.  To validate my point, Seth text me a picture showing that he just weighed micronized estradiol and he made a mess, not because his technique is bad, but because the powder hood was set up and Certified with too much velocity.


Blame the certifiers?

Now I will defend my friends in the Certification business because they make decisions based on the information given to them.  In Seth’s situation, the certifier correctly set up the hood based onthe manufacturer’s published standard.  Is it the certifier’s responsibility to understand every client’s business and intricate workflow processes?  Not really because they service many different industries such as semi-conductor, big pharma, industrial chemical, hospitals, universities, etc., and so understanding every client’s workflow/process seems like quite the undertaking.  Again, the certifiers are at the mercy of the manufacturer’s published standard for airflow.

So…blame the manufacturers?

Some hood manufacturers give a low range of airflow, say 60 linear feet per minute (abbreviated to “lfpm”, also sometimes expressed as “feet per minute” or fpm), which is measured at the face opening. Other manufacturers give a range of operation, say 60 lfpm to 90 lfpm, or 80 fpm to 100 fpm.  So if the certifier sets the powder hood up above the low range, or even within the manufacture’s defined range, then all is well, right? In Seth’s case, his powder hood was set up at 89 lfpm, which is too fast for weighing light fluffy and micronized powders. This is the underlying issue that I have been leading into.

Let me make another clarification at Seth’s hood operating at 89 lfpm.  That is the velocity at which air is entering the face opening and that is not necessarily the velocity at which air is hitting his weighing utensil.  A well-designed hood will utilize airfoils around the face opening and the purpose of those rounded airfoils is to smooth out the turbulent air.  There are only two types of air, smooth and turbulent.  The purpose of the hood is to take the room’s turbulent air and smooth it to laminar, so as to not disrupt the powders being weighed.  The hood’s airfoils work on the Bernoulli principle, much like an airplane wing.  Once the air entering the face opening comes about 12 inches or so the powder hood, the velocity drops down 10 to 15 additional lfpm.  However, the airfoils can only do so much work based on velocity.  If the velocity is too high then turbulence can occur and/or the velocity passing over the weighing utensil will whisk away the powder.  If powder is pulled off the spatula and splattered on the hood’s work surface then that is wasted product and more importantly, wasted money.

No finger pointing: find the SOLUTION!

Process improvement strategies are implemented to save time and money.  As you can see, having the hoods and engineering controls set up correctly (based on your specific needs) to minimize waste is a process improvement, and just one of many very small, yet effective process improvements we can implement in our pharmacies.  The bigger takeaway from this blog post is that the workflow processes much match the engineering controls to be effective.  The certifier is an important link between the engineering and the process, so I encourage you to talk to your certifiers and at least get their opinions on this topic.  Also, let me know if you have any questions or comments about this topic:  bryankprince@gmail.com

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