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A novel approach to study the pMDI plume using an infrared camera and to evaluate the aerodynamic properties after
Nitesh K Kunda1, Julia Hautmann1, Sebastián E Godoy2
1Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, USA.
Abstract:
Plume characteristics, such as temperature and velocity, emitted from pMDIs could significantly affect the dose delivered to the lung. Currently, high speed cameras and thermocouples are used separately to evaluate these parameters. We used a low-noise infrared camera to evaluate both the temperature and velocity of the emitted plume from pMDIs. Additionally, we investigated whether the fine particle fraction (FPF) is affected when time between actuations is varied. We tested three different albuterol sulfate pMDIs: ProAir® HFA, Proventil® HFA, and Ventolin® HFA. The plume and aerodynamic characteristics from these pMDIs were evaluated, after varying the time between actuations (15, 30, 60, and 120s), using the infrared camera and a next generation impactor, respectively. The aerodynamic characteristics were evaluated with and without a valved holding chamber (VHC). ProAir HFA had the softest plume followed by Proventil HFA and Ventolin HFA. Further, Ventolin HFA was slightly cooler and had significantly lower FPF than ProAir HFA and Proventil HFA. All inhalers had higher FPF when used with VHC. Further, we observed that the time between actuations affected the FPF across pMDIs. Moreover, generalized guidelines suggesting one-minute interval between actuations for pMDIs should be reconsidered, with and without a VHC.
Insights
Evaluating plume characteristics from metered-dose inhalers (MDIs) using infrared cameras reveals significant differences in temperature and velocity. These factors impact lung delivery and suggest reconsidering standard actuation intervals.
Area of Science:
- Pharmaceutical Sciences
- Respiratory Medicine
- Biomedical Engineering
Background:
- Metered-dose inhalers (MDIs) are crucial for delivering medication to the lungs.
- Plume characteristics like temperature and velocity influence the delivered dose.
- Current evaluation methods for plume parameters are often separate and complex.
Purpose of the Study:
- To utilize a single low-noise infrared camera for evaluating both temperature and velocity of MDI plumes.
- To investigate the impact of varying actuation intervals on the fine particle fraction (FPF).
- To compare plume and aerodynamic characteristics of three albuterol sulfate MDIs.
Main Methods:
- Employed a low-noise infrared camera to measure plume temperature and velocity.
- Assessed aerodynamic characteristics using a next-generation impactor.
- Evaluated three albuterol sulfate MDIs (ProAir HFA, Proventil HFA, Ventolin HFA) with varied actuation intervals (15-120s) and with/without a valved holding chamber (VHC).
Main Results:
- ProAir HFA exhibited the softest plume, followed by Proventil HFA and Ventolin HFA.
- Ventolin HFA showed lower plume temperature and significantly lower FPF compared to ProAir HFA and Proventil HFA.
- All MDIs demonstrated higher FPF when used with a VHC, and FPF was affected by actuation intervals.
Conclusions:
- Plume characteristics vary significantly among different albuterol sulfate MDIs.
- The time interval between actuations influences the FPF, challenging current generalized guidelines.
- Reconsideration of the standard one-minute MDI actuation interval is warranted, irrespective of VHC use.
