Preparation and properties of inhalable nanocomposite particles: Effects of the size, weight ratio of the primary nanoparticles in nanocomposite particles and temperature at a spray-dryer inlet upon properties of nanocomposite particles

Nanoparticles are expected to be applicable to inhalation as carrier but there exist disadvantages because of their size. Their deposition dose to the lung will be small. To overcome this problem and utilize nanoparticles for inhalation, we have prepared nanocomposite particles as drug carriers targeting lungs. The nanocomposite particles are prepared as drug-loaded nanoparticles–additive complex to reach deep in the lungs and to be decomposed into nanoparticles when they deposit into lung. In this study, we examined the effect of preparation condition – inlet temperature, size of primary nanoparticles and weight ratio of primary nanoparticles – on the property of nanocomposite particles.When the size of primary nanoparticles was 400 nm and inlet temperature was 90 °C, only the nanocomposite particles containing between 45 and 55% of primary nanoparticles could be decomposed into nanoparticles in water. On the other hand, when the inlet temperature was 80 °C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameter of the nanocomposite particles was between 1.5 and 2.5 μm, independent of the weight ratio of primary nanoparticles.When the size of primary nanoparticles was 200 nm and inlet temperature was 70 °C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameters of them were almost 2.0 μm independent of the weight ratio of primary nanoparticles. When the nanocomposite particles containing nanoparticles with the size of 200 nm are prepared at 80 °C, no decomposition into nanoparticles was observed in water.Fine particle values, FPF, of the nanocomposite particles were not affected by the weight ratio of primary nanoparticles when they were prepared at optimum inlet temperature.