Novel sustained release microspheres for pulmonary drug delivery

Novel sustained release microspheres for pulmonary drug delivery
May 5, 2005
Robert O. Cook, a, Rupi K. Pannu b, and Ian W. Kellaway a
aDepartment of Pharmaceutics, University of London School of Pharmacy, 29/39 Brunswick Square, London, WC1N 1AX, UK
bPharmaceutical and Analytical R and D, AstraZeneca R and D Charnwood, Bakewell Road, Loughborough, LE11 5RH, UK
Journal of Controlled Release Volume 104, Issue 1 , 5 May 2005, Pages 79-90
You can view the abstract online. A subscription is required to view the full text or it can be purchased online.
Abstract
A novel process for generating sustained release (SR) particles for pulmonary drug delivery is described. High purity nanoparticles of a hydrophilic, ionised drug are entrapped within hydrophobic microspheres using a spray-drying approach. Sustained release of the model drug, terbutaline sulphate (TS), from the microspheres was found to be proportional to drug loading and phospholipid content. Microspheres with a 33% drug loading exhibited sustained release of 32.7% over 180 min in phosphate buffer. Release was not significantly different in simulated lung fluids. No significant burst release was observed which suggested that nanoparticles were coated effectively during spray-drying. The absence of nanoparticles at the microsphere surface was confirmed with confocal microscopy. The sustained release microspheres were formulated as a carrier-free dry powder for inhalation, and exhibited a favourable Fine Particle Fraction (FPF) of 46.5?1.8% and Mass Median Aerodynamic Diameter (MMAD) of 3.93?0.12 ?m.