title: Topical delivery of ocular therapeutics: carrier systems and physical methods.
abstract: OBJECTIVE
  The basic concepts, major mechanisms, technological developments and advantages of the topical application of lipid-based systems (microemulsions, nanoemulsions, liposomes and solid lipid nanoparticles), polymeric systems (hydrogels, contact lenses, polymeric nanoparticles and dendrimers) and physical methods (iontophoresis and sonophoresis) will be reviewed.
  
  
  RESULTS
  Although very convenient for patients, topical administration of conventional drug formulations for the treatment of eye diseases requires high drug doses, frequent administration and rarely provides high drug bioavailability. Thus, strategies to improve the efficacy of topical treatments have been extensively investigated. In general, the majority of the successful delivery systems are present on the ocular surface over an extended period of time, and these systems typically improve drug bioavailability in the anterior chamber whereas the physical methods facilitate drug penetration over a very short period of time through ocular barriers, such as the cornea and sclera.
  
  
  CONCLUSIONS
  Although in the early stages, the combination of these delivery systems with physical methods would appear to be a promising tool to decrease the dose and frequency of administration; thereby, patient compliance and treatment efficacy will be improved.
authors.affiliation: School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Joel G
authors.initials: JG
authors.lastname: Souza
authors.forename: Karina
authors.initials: K
authors.lastname: Dias
authors.forename: Tatiana Aparecida
authors.initials: TA
authors.lastname: Pereira
authors.forename: Daniela Spuri
authors.initials: DS
authors.lastname: Bernardi
authors.forename: Renata F V
authors.initials: RF
authors.lastname: Lopez
mesh_terms: D000287:Administration, Topical; D000867:Anterior Chamber / Q000187:drug effects*; D003261:Contact Lenses; D050091:Dendrimers / Q000008:administration & dosage; D016503:Drug Delivery Systems / Q000379:methods; D004655:Emulsions / Q000008:administration & dosage; D005128:Eye Diseases / Q000188:drug therapy*; D006801:Humans; D020100:Hydrogels / Q000008:administration & dosage; D008055:Lipids / Q000008:administration & dosage*; D008081:Liposomes / Q000008:administration & dosage; D053758:Nanoparticles
chemical_list: D050091:Dendrimers; D004655:Emulsions; D020100:Hydrogels; D008055:Lipids; D008081:Liposomes
keywords: contact lens; dendrimers; iontophoresis; nanoparticle; topical ocular delivery