A summary of the tech and talk from Tucson, location for Respiratory Drug Delivery (RDD) 2024.
Switching from the rain clouds of England to the desert skies of Tucson brings the environment into sharp focus. And there it stayed with discussions of Low Global Warming Potential (GWP) propellants for MDI reformulation, a key conference topic. But there was also plenty of lively debate, insight, and ideas across a wide range of other issues. Here’s my round-up.
Low GWP propellants are changing the MDI landscape, and fast
With the first reformulated products now approaching commercialism, the pace of change is accelerating. The speed of development has been impressive, and many attendees were happily sharing best practice and learnings. Workshops by Bespak/Honeywell, and by Kindeva, along with some excellent posters, point to an emerging roadmap for those looking for help. The testing workloads highlight the benefits of automation (see below).
Wherever you’re working, variability in the inhaler test environment is a challenge
Visitors from across the globe appear to share our conclusion that even with lab-wide environmental controls, fluctuations in temperature can be sufficient to impact inhaler test results; both seasonal and diurnal fluctuations in relative humidity can be equally detrimental. As a result, there was plenty of interest in our poster ‘Reducing Variability in the Inhaler Testing Environment’ and possible solutions.

Nasal vaccines and nose to brain continue to drive interest in nasal drug products
There were plenty of updates in these areas which is encouraging given their potential for clinical benefit. Both applications substantially increase requirements to effectively target specific nasal regions for drug deposition and to better understand in vivo behaviour. It was therefore great to see several posters indicating that the Alberta Idealised Nasal Inlet (AINI) is helping researchers with these tasks (see posters below).
RDD 2024 Posters | |
Macquarie University | Chun Yuen Jerry Wong Ehancing Nose-to-Brain Drug Delivery: A Comparative Study of Peptide Formulations Using a Multidose Nasal Spray |
Upperton Pharma Solutions | Lara Penn Successful Scale-Up of a Spray Dried Formulation for Nasal Drug Delivery |
Studies highlighting application of the AINI
The latest FDA Product Specific Guidances (PSGs) are a major step forward
The PSGs released in February this year are stimulating much debate. Incorporating routes for the demonstration of bioequivalence (BE) with in vitro testing as an alternative to clinical endpoint studies, these naturally focus attention on more clinically representative in vitro methods. FDA presentations on this topic were very helpful for those getting up to speed, alongside some industry perspectives on validating realistic APSD (Aerodynamic Particle Size Distribution) and inhaled dissolution methods.
RDD 2024 Poster | |
Oz-UK Limited | Daniel Lewis Case Studies on Reformulation of BDP MDIs using Low GWP Propellants HFO1234ze and HFA152a |
Work showing the application of inhaled dissolution methods to demonstrate BE for reformulated MDIs
Delivering high drug payloads to the lungs remains a challenge
In the clinic the ability to deliver higher drug dosages, directly to the lungs would help to address unmet therapeutic need for multiple diseases. However, there are both biological and technical hurdles to overcome. Several groups are highly active in this area, and it was interesting to see the progress being made.
Working more efficiently is becoming more important than ever
The response to our workshop ‘Automating Inhaled and Nasal Drug Product Testing: Lower Variability, Higher Productivity’ was very encouraging. Attendance levels were high, and we enjoyed some engaging post-workshop discussions. MDI reformulation, the upswing in nasal drug product development, and the new routes for demonstrating BE are all driving up the analytical workload (see poster below). There is a genuine desire to lighten the load and automation can help. Effective automation strategies increase testing throughput and free up analysts for more valuable activities. Simultaneously they reduce the potential for harms such as repetitive strain injury, and mitigate variability, generating more consistent data with fewer anomalous results.
RDD 2024 Poster | |
Kindeva Drug Delivery | James Drake Practical Considerations for Conducting Successful In Vitro Bioequivalence Studies on Inhalers |
Industry insight into test burden associated with optimising the value/application of in vitro methods

In summary, an excellent, informative, and engaging week, in a great location. Thank you to the RDD organisers.
If you’d like to know more about the topics we were focusing on, then read our application note on environmental variability in the lab. Or explore our solutions and strategies for automation.