Pulmonary targeting with biodegradable salbutamol-loaded nanoparticles

BACKGROUND: Aerosol therapy using particulate drug carriers has become an increasingly attractive method to deliver therapeutic or diagnostic compounds to the lung. Polymeric nanoparticles are widely investigated carriers in nanomedicine. The targeted and controlled release of drugs from nanoparticles for pulmonary delivery, however, is a research field that has been so far rather unexploited. Therefore, the objective of this study was to compare the pulmonary absorption and distribution characteristics of salbutamol after aerosolization as solution or entrapped into novel polymeric nanoparticles in an isolated rabbit lung model (IPL). METHODS: Physicochemical properties, morphology, encapsulation efficiency, in vitro drug release, stability of nanoparticles to nebulization, as well as pulmonary drug absorption and distribution after nebulization in the IPL were investigated. RESULTS: Salbutamol-loaded poly(D,L-lactide-co-glycolide) (PLGA) and poly(vinyl sulfonate-co-vinyl alcohol)-graft-poly(D,L-lactide-co-glycolide) (VS(72)-10) nanoparticles were prepared by a modified solvent displacement technique with a mean particle size of approximately 120 nm and a polydispersity index below 0.150. VS(72)-10 nanoparticles showed a more negative zeta-potential of -54.2 +/- 3.3 mV compared to PLGA nanoparticles (-36.5 +/- 2.6 mV). Salbutamol encapsulation efficiency was 25.2 +/- 4.9% and 63.4 +/- 3.5% for PLGA and VS(72)-10 nanoparticles, respectively. After nebulization utilizing the MicroSprayer physicochemical properties of salbutamol-loaded VS(72)-10 nanoparticles were virtually unchanged, whereas nebulized salbutamol-loaded PLGA nanoparticles showed a significant increase in mean particle size and polydispersity. In vitro release studies demonstrated a sustained release of the encapsulated salbutamol from VS(72)-10 nanoparticles. In parallel, a sustained salbutamol release profile was observed after aerosol delivery of these particles to the IPL as reflected by a lower salbutamol recovery in the perfusate (40.2 +/- 5.8%) when compared to PLGA nanoparticles (55.2 +/- 9.1%) and salbutamol solution (62.8 +/- 7.1%). CONCLUSIONS: The current study suggests that inhalative delivery of biodegradable nanoparticles may be a viable approach for the treatment of respiratory diseases