Electrostatics of pharmaceutical inhalation aerosols.
OBJECTIVE
This review focuses on the key findings and developments in the rapidly expanding research area of pharmaceutical aerosol electrostatics.


RESULTS
Data from limited in-vivo and computational studies suggest that charges may potentially affect particle deposition in the airways. Charging occurs naturally in the absence of electric fields through triboelectrification, that is contact or friction for solids and flowing or spraying for liquids. Thus, particles and droplets emitted from pulmonary drug delivery devices (dry powder inhalers, metered dose inhalers with or without spacers, and nebulisers) are inherently charged. Apparatus with various operation principles have been employed in the measurement of pharmaceutical charges. Aerosol charges are dependent on many physicochemical parameters, such as formulation composition, device construction, relative humidity and solid-state properties. In some devices, electrification has been purposefully applied to facilitate powder dispersion and liquid atomisation.


CONCLUSIONS
Currently, there are no regulatory requirements on characterising electrostatic properties of inhalation aerosols. As research in this area progresses, the new knowledge gained may become valuable for the development and regulation of inhalation aerosol products.
Kwok
Philip Chi Lip
PC
Advanced Drug Delivery Group, Faculty of Pharmacy, The University of Sydney, New South Wales, Australia.
Chan
Hak-Kim
HK
D000280:Administration, Inhalation; D000336:Aerosols / Q000737:chemistry*; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems / Q000379:methods*; D006801:Humans; D009330:Nebulizers and Vaporizers; D011208:Powders; D012137:Respiratory System; D055672:Static Electricity; D013678:Technology, Pharmaceutical
D000336:Aerosols; D011208:Powders