Effect of Aerolizer® and capsule materials on the electrification of spray dried mannitol particles

PHILIP CHI LIP KWOK, Priscilla Tran, Hak-Kim Chan

Advanced Drug Delivery Group, Faculty of Pharmacy, Building A15, The University of Sydney, NSW 2006, Australia

     Abstract Number: 349
     Last modified: May 10, 2010

Abstract
Objective: To examine the effect of Aerolizer® and capsule construction materials on the electrostatic charges of dispersed mannitol particles.
Materials and Methods: Aerolizers® constructed from five different polymers were studied. These included acrylonitrile butadiene styrene (ABS; the original inhaler material), polypropylene (PP), low density polyethylene (LDPE), polyoxymethylene (POM) and nylon. The dielectric constants of these materials at 1 MHz are 2.40 – 3.80, 2.20 – 2.60, 2.25 – 2.35, 3.70, and 3.40 – 3.60, respectively. Hydroxylpropyl methylcellulose (HPMC) capsules were used with all inhaler materials. Gelatin capsules were also tested with ABS Aeroslizers®. Ten milligrams of spray dried mannitol loaded into the capsule and inhaler were dispersed at 30 L/min into a modified electrical low pressure impactor (ELPI) for charge measurement. All runs were conducted under ambient conditions (26 ± 1°C, 50 ± 10% relative humidity). The charge profiles between the various inhaler and capsule materials were compared.
Results and Discussion: The spray dried mannitol produced bipolar charges for all inhaler-capsule combinations, with the higher size fractions (> 2 micro-metres) being net negative and the lower ones (< 2 micro-metres) net positive. No significant difference was found in the charge profiles between the various inhaler materials for HPMC capsules. The charging of mannitol from ABS Aerosizers® also showed no change with gelatin capsules. This indicates that the electrification of mannitol is not susceptible to change under the given conditions or that the inhaler or capsule materials may not influence aerosol charging in general.
Conclusions: The charging of mannitol particles from Aerosizers® was not influenced by the inhaler construction material when HPMC capsules were used or by the capsule material when ABS inhalers were used. More investigation is needed to confirm this lack of effect under broader conditions.