Recent years have seen significant effort devoted to formulate therapeutic agents in biocompatible nanocomposites such as nanoparticles, nanocapsules, micellar systems and conjugates as drug delivery systems. Application of nanotechnology for diagnosis, monitoring, disease therapy, and control of biological systems was referred to as “nanomedicine”, and it has been receiving extensive attention over the past decade.
Among these drug delivery systems, nanoparticles have received a considerable attention for the delivery of wide variety of drugs as well as biological macromolecules and vaccines. Nanoparticles have been defined as submicron sized drug carriers, where the drug is either adsorbed on the surface or encapsulated within the particle. These nanoparticles can be prepared from natural and synthetic polymers that may or may not be biodegradable depending on their route of administration. Biodegradable polymeric nanoparticles administered intravenously have been successfully used to control and target drug to specific site of action at the therapeutically optimal rate.
Owing to the size in nanometric range, these biodegradable nanoparticles have a potential to escape the reticulo-endothelial system and thus an increase in the residence time is seen with these drug delivery systems. Nanoparticles can also overcome the multiple drug resistance phenotype mediated by glycoprotein-P, resulting in increased drug content inside the cells and because of this reason biodegradable nanoparticles have been widely studied for P-gP substrates like paclitaxel.
The purpose of this study was to evaluate the effect of process (homogenization speed and evaporation time) and formulation (aqueous/organic phase ratio, surfactant concentration, polymer type and concentration, and drug amount) variables on the preparation of paclitaxel-loaded biodegradable polymeric nanoparticles using modified solvent evaporation technique.
Thereafter, a formulation was selected and subjected to evaluation of inclusion of a co-surfactant for further reduction of particle size. Particle size, encapsulation efficiency and in-vitro drug release kinetics were evaluated. It was observed that the inclusion of vitamin E TPGS (0.01%), Poloxamer 188 (0.5%) or Tween 80 (0.25%) reduced the particle size of nanoparticles to 230, 244 or 301 nm from 438 nm, respectively. Encapsulation efficiency increased for both vitamin E TPGS and Poloxamer 188 up to concentration at 0.010% and 0.25%, respectively, while this was not the case for Tween 80.
Comparison of drug release kinetics demonstrated that drug release accelerated from paclitaxel-loaded biodegradable nanoparticles prepared with the inclusion of Tween 80 but was delayed for Poloxamer 188 and vitamin E TPGS. Thus, it was concluded that the particle size of the nanoparticles could be reduced further and the paclitaxel release kinetics could easily be adjusted by taking advantage by the inclusion of a co-surfactant.