title: Vitreous concentration of topically applied brimonidine-purite 0.15%.
abstract: OBJECTIVE
  The aim of this study was to determine the vitreous brimonidine concentration of topically applied brimonidine-Purite 0.15%.
  
  
  METHODS
  Patients scheduled for a pars plana vitrectomy were invited to participate in this study after institutional review board (IRB) approval was obtained. Each patient was asked to apply brimonidine-Purite (0.15%) drops in the designated eye either every 12 h (b.i.d.; 9 patients) or every 8 h (t.i.d.; 10 patients) for the 2 weeks proceeding scheduled surgery. The importance of the last topical dose being 12 h (b.i.d. group) or 8 h (t.i.d. group) before the scheduled surgery, was emphasized. Four (4) patients served as controls and did not receive any drops. Vitreous (approximately 0.5-1.0 mL) was aspirated prior to opening the infusion line. Specimens were frozen at -68 degrees C until analyzed.
  
  
  RESULTS
  In the b.i.d. group, the mean concentration of brimonidine was 16.74 nM+/-10.33 standard deviation (range, 0.42-34.68 nM; median, 16.38); in the t.i.d. group, the mean concentration of brimonidine was 19.16 nM+/-15.40 standard deviation (range, 0.22-39.48 nM; median, 16.98). A significant difference was observed between the (no drug) control vitreous brimonidine levels and b.i.d. or t.i.d. vitreous levels (P<0.01, <0.01, respectively; n=4, 9, and 10, respectively); and in brimonidine levels between t.i.d. phakic patients and t.i.d. patients with posterior chamber lens (P=0.04; n=4 and 6, respectively).
  
  
  CONCLUSIONS
  Brimonidine-Purite 0.15%, topically applied b.i.d. or t.i.d. for 2 weeks prior to collection, acquired vitreous levels of brimonidine at or above the 2-nM concentration known to activate the neuroprotective alpha-2 receptor in animals.
authors.affiliation: Eyecare Physicians and Surgeons, LLC, and Storm Eye Institute, Medical University of South Carolina, Charleston, SC 29403, USA. kentalex@bellsouth.net
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Kent
authors.forename: Lowery
authors.initials: L
authors.lastname: King
authors.forename: Luanna R
authors.initials: LR
authors.lastname: Bartholomew
mesh_terms: D000287:Administration, Topical; D000316:Adrenergic alpha-Agonists / Q000493:pharmacokinetics; D000368:Aged; D000959:Antihypertensive Agents / Q000493:pharmacokinetics*; D001682:Biological Availability; D000068438:Brimonidine Tartrate; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D009883:Ophthalmic Solutions / Q000493:pharmacokinetics; D011810:Quinoxalines / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014821:Vitrectomy; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D000316:Adrenergic alpha-Agonists; D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions; D011810:Quinoxalines; D000068438:Brimonidine Tartrate