title: Pharmacokinetics of a sustained-release dexamethasone intravitreal implant in vitrectomized and nonvitrectomized eyes.
abstract: OBJECTIVE
  To evaluate dexamethasone pharmacokinetics after implantation of a sustained-release dexamethasone (DEX) intravitreal implant in nonvitrectomized and vitrectomized eyes.
  
  
  METHODS
  The right eyes of 25 rabbits underwent vitrectomy; contralateral eyes served as nonvitrectomy controls. The 0.7-mg DEX implant was injected into both eyes, and drug concentrations were determined in the vitreous humor and retina for 31 days (on days 2, 8, 15, 22, and 31).
  
  
  RESULTS
  DEX was present in nonvitrectomized and vitrectomized eyes for at least 31 days. There were no statistically significant differences in DEX concentration between nonvitrectomized and vitrectomized eyes at any time point (P > 0.05). The maximum concentration of DEX in nonvitrectomized versus vitrectomized eyes for vitreous humor was 791 ng/mL (day 22) versus 731 ng/mL (day 22), respectively, and for retina it was 4110 ng/mL (day 15) versus 3670 ng/mL (day 22), respectively. Mean absorption (AUC(0-tlast)) of dexamethasone in nonvitrectomized and vitrectomized eyes was not different for both the vitreous humor (13,600 vs. 15,000 ng/day/mL; P = 0.73) and retina (67,600 vs. 50,200 ng/day/mL; P = 0.47).
  
  
  CONCLUSIONS
  The vitreoretinal pharmacokinetic profiles were similar between nonvitrectomized and vitrectomized eyes. These observations are consistent with clinical findings of the DEX implant in patients who have undergone vitrectomy and should reduce concerns about the use of the DEX implant in eyes that have undergone vitrectomy.
authors.affiliation: Research and Development, Allergan, Inc., Irvine, California 92612, USA. lin_joan-en@allergan.com
authors.forename: Joan-En
authors.initials: JE
authors.lastname: Chang-Lin
authors.forename: James A
authors.initials: JA
authors.lastname: Burke
authors.forename: Qing
authors.initials: Q
authors.lastname: Peng
authors.forename: Ton
authors.initials: T
authors.lastname: Lin
authors.forename: Werhner C
authors.initials: WC
authors.lastname: Orilla
authors.forename: Corine R
authors.initials: CR
authors.lastname: Ghosn
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Zhang
authors.forename: Baruch D
authors.initials: BD
authors.lastname: Kuppermann
authors.forename: Michael R
authors.initials: MR
authors.lastname: Robinson
authors.forename: Scott M
authors.initials: SM
authors.lastname: Whitcup
authors.forename: Devin F
authors.initials: DF
authors.lastname: Welty
mesh_terms: D000818:Animals; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000493:pharmacokinetics; D003907:Dexamethasone / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004195:Disease Models, Animal; D004343:Drug Implants; D005128:Eye Diseases / Q000188:drug therapy* / Q000378:metabolism / Q000601:surgery; D005500:Follow-Up Studies; D005938:Glucocorticoids / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D008657:Metabolic Clearance Rate; D057972:Posterior Eye Segment; D011817:Rabbits; D014821:Vitrectomy; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism* / Q000601:surgery
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D005938:Glucocorticoids; D003907:Dexamethasone