Assessing the Temperature of Thermally Generated Inhalation Aerosols
| Autor: | Peter D. Noymer, Dan J. Myers, Ryan Timmons, James Cassella |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Aerosols
Pulmonary and Respiratory Medicine Wet-bulb temperature Chemistry Nebulizers and Vaporizers Condensation Airflow Temperature Pharmaceutical Science Humidity Equipment Design Inhaled air Aerosol Drug Delivery Systems Pharmaceutical Preparations Environmental chemistry Administration Inhalation Vaporization Humans Technology Pharmaceutical Pharmacology (medical) Relative humidity |
| Zdroj: | Journal of Aerosol Medicine and Pulmonary Drug Delivery. 24:11-15 |
| ISSN: | 1941-2703 1941-2711 |
| Popis: | Condensation aerosols are produced when a drug is vaporized and then cools in the inhalation air. Because energy is applied to vaporize the drug, there is a potential concern that the air temperature might not be well tolerated. A literature review indicates that the proper metric for this is the wet-bulb temperature (T(wb)) of the inhaled air. T(wb) measures the total energy of the air, including moisture content, and reflects the potential impact on safety and tolerability.The Staccato® system (Alexza Pharmaceuticals, Mountain View, CA) uses thermal vaporization for aerosol generation and was used in a series of studies to characterize the peak transient value (peak T(wb)) of the air coming out of the device. These studies evaluated peak T(wb) over a range of air flow rates (15-45 L/min), ambient conditions [15-30°C and 15 to 90% relative humidity (RH)] and vaporization temperatures.Under nominal conditions (30 L/min air flow, 25°C and 50% RH), peak T(wb) was 28.8 ± 0.6°C (mean ± standard deviation). Over the range of operating conditions tested, mean values for peak T(wb) ranged from 26.2 to 33.3°C with similarly low variances. When operated under a combination of extreme conditions, peak T(wb) was measured to be 39.9 ± 0.1°C (mean ± standard deviation).Technical standards indicate that the upper limit on inhaled T(wb) for safety and tolerability is 50°C, and inhalation at that temperature can be sustained for 1 h. Peak values of T(wb) from the Staccato system are well below that threshold, approximately 30°C at nominal conditions and approximately 40°C at a combination of extreme conditions. Moreover, the peak lasts for only a few seconds, well under the time limit of 1 h. These results suggest that aerosols generated with the Staccato system will be safe and well tolerated. |
| Databáze: | OpenAIRE |
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