Physical and chemical stability of drug nanoparticles.

As nano-sizing is becoming a more common approach for pharmaceutical product development, researchers are taking advantage of the unique inherent properties of nanoparticles for a wide variety of applications. This article reviews the physical and chemical stability of drug nanoparticles, including their mechanisms and corresponding characterization techniques. A few common strategies to overcome stability issues are also discussed.

Formation, characterization, and fate of inhaled drug nanoparticles.

Nanoparticles bring many benefits to pulmonary drug delivery applications, especially for systemic delivery and drugs with poor solubility. They have recently been explored in pressurized metered dose inhaler, nebulizer, and dry powder inhaler applications, mostly in polymeric forms. This article presents a review of processes that have been used to generate pure (non polymeric) drug nanoparticles, methods for characterizing the particles/formulations, their in-vitro and in-vivo performances, and the fate of inhaled nanoparticles.

Why inhaling salt water changes what we exhale.

We find that inhaling salt water diminishes subsequently exhaled biomaterial in man and animals due to reversible stabilization of the airway lining fluid (ALF)/air interface as a novel potential means for control of the spread of airborne infectious disease. The mechanism of this phenomenon relates to charge shielding of mucin or mucin-like macromolecules that consequently undergo gelation; this gelation alters the physical properties of the ALF surface and reduces its breakup. Cations in the nebulized solution and apparent surface viscoelasticity of the ALF (more than any other ALF intrinsic physical property) appear to be responsible for the reduced tendency of the ALF to disintegrate into very small droplets. We confirm these effects in vivo and show their reversibility through nebulization of saline solutions to anesthetized bull calves.

Aerosol flow reactor method for synthesis of drug nanoparticles.

An aerosol flow reactor method, a one-step continuous process to produce nanometer-sized drug particles with unimodal size distribution, was developed. This method involves first dissolving the drug material in question into a suitable solvent, which is then followed by atomising the solution as fine droplets into carrier gas. A heated laminar flow reactor tube is used to evaporate the solvent, and solid drug nanoparticles are formed. In this study, the effect of drying temperature on the particle size and morphology was examined. A glucocorticosteroid used for asthma therapy, beclomethasone dipropionate, was selected as an experimental model drug. The geometric number mean particle diameter increases significantly with increasing reactor temperatures due to formation of hollow nanoparticles. Above 160 degrees C, however, further increase in temperature results in decreasing particle size. The produced nanoparticles are spherical and show smooth surfaces at all studied experimental conditions.