title: Applications of poloxamers in ophthalmic pharmaceutical formulations: an overview.
abstract: BACKGROUND
  An ideal ophthalmic formulation is one that not only prolongs the contact time of the vehicle on the ocular surface but also slows down the drug elimination. The poor bioavailability and therapeutic response exhibited by the conventional ophthalmic solutions due to pre-corneal elimination of the drug may be overcome by the use of in situ gel forming systems. In situ gelling systems increase the viscosity by changing the pH or temperature in the pre-corneal region and lead to an increase of drug bioavailability by slowing drainage. Poloxamers are polyols with thermal gelling properties which are frequently included in ophthalmic formulations to improve the ocular bioavailability of drugs by increasing vehicle viscosity.
  
  
  METHODS
  An overview on the unique physiological characteristics of ocular globe and the limitations and disadvantages of the conventional ophthalmic pharmaceutical formulations. Readers will appreciate the different strategies to improve the absorption of drugs in the ocular globe, especially the incorporation of poloxamers in ophthalmic formulations, understanding the main advantages of the poloxamers and also learning about the different examples of applications of these polymers in ophthalmic pharmaceutical formulations.
  
  
  CONCLUSIONS
  Poloxamers offers a new strategy to improve bioavailability and decrease the side effects induced by the systemic absorption of topically applied ophthalmic drugs.
authors.affiliation: University of Porto, Faculty of Pharmacy, Drug Sciences Department, Laboratory of Pharmaceutical Technology, Portugal. dcf11001@mail.ff.up.pt
authors.forename: Hugo
authors.initials: H
authors.lastname: Almeida
authors.forename: Maria Helena
authors.initials: MH
authors.lastname: Amaral
authors.forename: Paulo
authors.initials: P
authors.lastname: Lobão
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Sousa Lobo
mesh_terms: D000818:Animals; D001682:Biological Availability; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems; D005128:Eye Diseases / Q000188:drug therapy; D005782:Gels / Q000737:chemistry; D006801:Humans; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry*; D014783:Viscosity
chemical_list: D005782:Gels; D009883:Ophthalmic Solutions; D004364:Pharmaceutical Preparations; D020442:Poloxamer