TI: Comparison of particle sizing techniques in
the case of inhalation dry powders.
AU: Bosquillon,-C; Lombry,-C; Preat,-V; Vanbever,-R
AD: Universite catholique de Louvain, School of Pharmacy, Department
of Pharmaceutical Technology, Avenue E. Mounier, 73 UCL 73.20, 1200 Brussels,
Belgium.
SO: J-Pharm-Sci. 2001 Dec; 90(12): 2032-41
JN: Journal-of-pharmaceutical-sciences
PY: 2001
AB: The objectives of this work were (i) to validate electrical
zone sensing and laser diffraction for the analysis of primary particle
size in the case of inhalation dry powders and (ii) to study the influence
of the aggregation state of the powder on the sizing techniques. Free-flowing
dry powders were prepared by spray-drying with a combination of albumin,
lactose, and dipalmitoylphosphatidylcholine. The replacement of lactose
by mannitol, the removal of albumin, and the atomization at high relative
humidity all increased powder cohesion. Automated measurements were compared
with primary particle sizes collected by light and electron microscopy.
The mass mode obtained by electrical zone sensing and the mass median diameter
measured by laser diffraction following dispersion with compressed air
at a pressure of 3 bar or following suspension in water and ultrasonic
dispersion at a power of 60 W for 30 s each provided primary particle sizes
close to microscopy measurements. However, these conditions only applied
in the case of slightly to moderately aggregated powders. For strongly
agglomerated powders, an exact measurement of the size was only collected
by laser diffraction in the wet state combined with ultrasonic dispersion.
Our study underlies how measurement of primary particle size highly depends
on both powder material and proper particle dispersion. Copyright 2001
Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci
90:2032-2041, 2001