title: Biodegradable intrascleral implant for sustained intraocular delivery of betamethasone phosphate.
abstract: OBJECTIVE
  To evaluate the feasibility of using a biodegradable intrascleral implant for intraocular sustained delivery of betamethasone phosphate (BP).
  
  
  METHODS
  The intrascleral implant (0.5 mm thick and 4 mm in diameter) was made of poly(DL-lactide) containing 25% betamethasone phosphate. The in vitro release of BP from the implant was evaluated by high-performance liquid chromatography (HPLC). The implants were placed into a scleral pocket in the rabbit's eye. The concentrations of BP in the aqueous humor, vitreous, and retina-choroid were measured by HPLC. The toxicity and biocompatibility of the implant were evaluated by slit lamp examination, electroretinography, and light microscopy.
  
  
  RESULTS
  In vitro studies demonstrated that the implants released BP in a biphasic pattern for at least 8 weeks. The BP concentrations in the vitreous and the retina-choroid remained within the concentration range capable of suppressing inflammatory responses for more than 8 weeks. The BP concentration was greater in the retina-choroid than in the vitreous. In the aqueous humor, BP was below the detection limit during the observation period. No significant toxicity to the retina was observed. Also, the implant showed good biocompatibility in the eye.
  
  
  CONCLUSIONS
  These results suggest that the intrascleral implant would be a promising system for delivery of steroid to the posterior segment of the eye.
authors.affiliation: Department of Ophthalmology, Nagoya City University Medical School, Nagoya, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Okabe
authors.forename: Hideya
authors.initials: H
authors.lastname: Kimura
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kunou
authors.forename: Komei
authors.initials: K
authors.lastname: Okabe
authors.forename: Aki
authors.initials: A
authors.lastname: Kato
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Ogura
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D001623:Betamethasone / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D002829:Choroid / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D004343:Drug Implants; D004596:Electroretinography; D005240:Feasibility Studies; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011091:Polyesters; D011817:Rabbits; D012160:Retina / Q000378:metabolism; D012590:Sclera / Q000187:drug effects*; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D005938:Glucocorticoids; D011091:Polyesters; C033616:poly(lactide); C028994:betamethasone sodium phosphate; D001623:Betamethasone