title: A poloxamer/chitosan in situ forming gel with prolonged retention time for ocular delivery.
abstract: The aim of the present work was to obtain an ophthalmic delivery system with improved mechanical and mucoadhesive properties that could provide prolonged retention time for the treatment of ocular diseases. For this, an in situ forming gel comprised of the combination of a thermosetting polymer, poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO, poloxamer), with a mucoadhesive agent (chitosan) was developed. Different polymer ratios were evaluated by oscillatory rheology, texture and mucoadhesive profiles. Scintigraphy studies in humans were conduced to verify the retention time of the formulations developed. The results showed that chitosan improves the mechanical strength and texture properties of poloxamer formulations and also confers mucoadhesive properties in a concentration-dependent manner. After a 10-min instillation of the poloxamer/chitosan 16:1 formulation in human eyes, 50-60% of the gel was still in contact with the cornea surface, which represents a fourfold increased retention in comparison with a conventional solution. Therefore, the developed formulation presented adequate mechanical and sensorial properties and remained in contact with the eye surface for a prolonged time. In conclusion, the in situ forming gel comprised of poloxamer/chitosan is a promising tool for the topical treatment of ocular diseases.
authors.affiliation: Department of Pharmaceutical Sciences, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Taís
authors.initials: T
authors.lastname: Gratieri
authors.forename: Guilherme Martins
authors.initials: GM
authors.lastname: Gelfuso
authors.forename: Eduardo Melani
authors.initials: EM
authors.lastname: Rocha
authors.forename: Victor Hugo
authors.initials: VH
authors.lastname: Sarmento
authors.forename: Osvaldo
authors.initials: O
authors.lastname: de Freitas
authors.forename: Renata Fonseca Vianna
authors.initials: RF
authors.lastname: Lopez
mesh_terms: D000268:Adhesiveness; D000287:Administration, Topical; D000328:Adult; D048271:Chitosan / Q000737:chemistry*; D003315:Cornea / Q000378:metabolism; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D005782:Gels; D006801:Humans; D011092:Polyethylene Glycols / Q000737:chemistry*; D011409:Propylene Glycols / Q000737:chemistry*; D011877:Radionuclide Imaging; D012212:Rheology; D013997:Time Factors; D055815:Young Adult
chemical_list: D003692:Delayed-Action Preparations; D005782:Gels; C116176:PEO-PPO-PEO; D011409:Propylene Glycols; D011092:Polyethylene Glycols; D048271:Chitosan