title: Chitosan-tripolyphosphate nanoparticles as a possible skin drug delivery system for aciclovir with enhanced stability.
abstract: OBJECTIVE
  The aim of the present study was to create a skin delivery system based on chitosan-tripolyphosphate nanoparticles for aciclovir with enhanced chemical stability.
  
  
  METHODS
  Nanoparticles were formed spontaneously using ionotropic gelation with tripolyphosphate. Two different sizes of aciclovir-loaded nanoparticles were characterised in terms of zeta potential, particle size and polydispersity index.
  
  
  RESULTS
  Standard diffusion experiments using Franz-type diffusion cells showed reasonable skin permeability that depended on particle size and chitosan content. The larger the nanoparticle, having a higher chitosan content, the better the aciclovir permeation through porcine skin. Differential scanning calorimetry studies showed a remarkable decrease in the typical transition temperature, indicating an interaction between skin lipid bilayer and the nanoparticles. Moreover, the chemical stability of aciclovir was significantly increased by the nanoparticle system. After the observation period of 5 weeks, aciclovir incorporated into nanoparticles had undergone photo-oxidation to a significantly lower extent than pure aqueous solution. This degradation product of aciclovir was analysed using LC/MS, and its identity established.
  
  
  CONCLUSIONS
  These studies demonstrate that incorporation of aciclovir into chitosan-tripolyphosphate nanoparticles significantly improves its chemical stability. Moreover, skin diffusion studies in vitro showed improved permeation of aciclovir from the nanoparticle system, especially from nanoparticles with higher chitosan content.
authors: Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria.
authors: Amra
authors: A
authors: Hasanovic
authors: Martin
authors: M
authors: Zehl
authors: Gottfried
authors: G
authors: Reznicek
authors: Claudia
authors: C
authors: Valenta
mesh_terms: D000212:Acyclovir / Q000737:chemistry* / Q000627:therapeutic use; D000998:Antiviral Agents / Q000737:chemistry* / Q000627:therapeutic use; D002151:Calorimetry; D048271:Chitosan / Q000737:chemistry / Q000494:pharmacology*; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D005782:Gels; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D010539:Permeability; D011122:Polyphosphates / Q000737:chemistry*; D012867:Skin / Q000187:drug effects; D012869:Skin Absorption / Q000187:drug effects*; D013696:Temperature
chemical_list: D000998:Antiviral Agents; D004337:Drug Carriers; D005782:Gels; D008051:Lipid Bilayers; D011122:Polyphosphates; D048271:Chitosan; C005692:triphosphoric acid; D000212:Acyclovir