Now, taking a step further, I believe we have to move forward and say okay, if we accept the less size-selective nature of the respiratory tract, why not abbreviate the multi-stage impactor to do something similar to what goes on in reality when aerosol particles are inhaled? Abbreviation to a single or two-stage system won’t be perfect because of the dissimilarity in size-selectivity that we have just mentioned. However, I believe that such developments to the testing equipment are a good start as they have the potential to eliminate wasted time recovering drug particles from more components than is strictly necessary.
In fact, reverse-flow gas cyclones have collection efficiency-aerodynamic size curves that are less size selective than impactor stages and are therefore closer to the selectivity for particle deposition in the major regions of the human respiratory tract. It is therefore a possibility that down the road, instruments based around this technology might bring closer convergence between laboratory-based measurements and reality for inhaled particle deposition.
For me, personally, taking a largely unknown laboratory of a small aerosol–based device company having little contact with the drug side of the business to the point in which that laboratory is internationally recognized by stakeholders involved with orally inhaled product development has been one of the most satisfying changes. I am pleased to be shortly leaving the TMI Aerosol Laboratory in a very good state of affairs. That personal goal has taken a long time to happen because the process has not been straightforward.
Q: What do you think is the greatest necessity for future improvements in the development of OINDPs?
A: Probably getting younger people to understand the basics of aerosol physics so that when they come into whatever roles they occupy as stakeholders, maybe working in a pharmaceutical/device manufacturing company or for a regulatory agency, they understand the basic principles, and they can apply that knowledge to whatever circumstance they are in. It’s no secret that some regulatory agencies have had difficulty recruiting people with the appropriate background knowledge in inhaled aerosol drug delivery.
In response to these needs, I think we’ve got to strengthen the academic side so that people who leave college with PhDs, PharmDs and the like, have adequate knowledge of the inhalation dosage form. Currently, the universities focus mainly on solid and liquid-based dosage forms because these products dominate the marketplace, and therefore knowledge of these forms is the “bread and butter” of coursework.
In my opinion, the inhalation route of administration for both topical and systemic therapy is important enough that schools aiming to produce graduates with a well-rounded knowledge of the discipline should devote significant content of their course material to drug products for this therapeutic route.
Q: What do you think would be the best way to make that happen?
A: One way that is becoming more open to older people who have career lifetimes of acquired knowledge and experience, and who are now retiring, is to pass on this expertise directly to students. This is why I’m hoping to work with the College of Pharmacy at the University of Hawaii.
I fundamentally believe that if you get to a point where you’ve been richly blessed, as I and my family have been, that it is appropriate to be putting something back into the community at large. We have also been recipients of many good things from our visits to Hawaii.
There are likely many other academic institutions where this knowledge transfer can happen, especially to schools that don’t currently have a lot of inhalation-related expertise. My advice to my colleagues in this position is to get to know your local university pharmacy department before you retire, and thereby become part of that giving of information that will help train the next generation.
