In vitro evaluation of the DP-4M PennCenturyTM dry powder insufflator

M. Hoppentocht, C. Hoste, P. Hagedoorn, H.W. Frijlink, A.H. de Boer

Formulations for inhalation have to be screened in animal studies for therapeutic efficacy and safety aspects and both may be significantly affected by the dose and the particle size distribution (PSD) of the administered aerosol. A frequently used apparatus for pulmonary delivery of powder formulations in mice studies is the PennCentury™ DP-4M dry powder insufflator. To make researchers of future preclinical animal studies with the DP-4M insufflator aware of the pitfalls regarding the conclusions to be drawn from their data, we investigated the dispersion behaviour of the insufflator using different powder preparation techniques for four different compounds. The primary PSDs of the different formulations were determined by laser diffraction analysis. To measure the PSDs of the aerosols obtained with the insufflator, the same diffractometer was used in combination with an in-house constructed adapter. The dispersion efficiency and delivered dose were highly affected by the amount of air available for dispersion; the 200 µl of air recommended for the type of insufflator for mice used was insufficient for adequate dispersion. In contrast, the weighed dose did not have a profound effect on the dispersion behaviour and the delivered dose. Also the physico-chemical powder properties and the applied particle preparation technique influenced the amount and PSD of the delivered aerosol only to a limited extend, with a few exceptions. We advise researchers to investigate the performance from the insufflator with the formulation under investigation prior to in vivo studies and it may be necessary to optimise the formulation for administration to mice.

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