title: In vitro human scleral permeability of fluorescein, dexamethasone-fluorescein, methotrexate-fluorescein and rhodamine 6G and the use of a coated coil as a new drug delivery system.
abstract: OBJECTIVE
  To determine the in vitro human scleral permeability of several dyes and drugdye combinations with varying molecular weights (MW) and lipid solubilities (fluorescein, dexamethasone-fluorescein, methotrexate-fluorescein, and rhodamine). Coils coated with rhodamine were also evaluated for scleral permeability and sustained release.
  
  
  METHODS
  Scleral sections excised from moist chamber stored human globes were mounted in a 2-compartment perfusion chamber. A small depot of drug/dye (100 microl of 10(-4) M fluorescein, dexamethasone-fluorescein, methotrexate-fluorescein or rhodamine) or a coated coil in 100 microl of BSS was added to the episcleral surface while perfusing BSS to the choroidal side. The perfusate was collected and measured for fluorescence. Permeability was calculated as Ktrans from the flux measurements.
  
  
  RESULTS
  Ktrans values (cm/sec, mean +/- SE) for the studied dyes and drug-dye combinations were 5.21 +/- 0.71 x 10(-6) for fluorescein, 1.64 +/- 0.17 x 10(-6) for dexamethasone-fluorescein, 3.36 +/- 0.62 x 10(-6) for methotrexate-fluorescein, 1.86 +/- 0.39 x 10(-6) for rhodamine and 2.18 +/- 0.23 x 10(-6) for the rhodamine from the coils. We found a significant difference between the permeability of the sclera to fluorescein and dexamethasone-fluorescein (P < 0.001), methotrexate-fluorescein (P < 0.05) and rhodamine (P < 0.001). Steady state flux was observed from the rhodamine coil.
  
  
  CONCLUSIONS
  The rank order of scleral permeability to the studied dyes is as follows: fluorescein > methotrexate-fluorescein > rhodamine coil > rhodamine 6G > dexamethasone-fluorescein. Differences in scleral permeability are related to MW and lipid solubility. Prolonged transscleral diffusion of rhodamine delivered by solution and by coil are similar.
authors.affiliation: Department of Ophthalmology, Emory University, Atlanta, Georgia, 30322, USA.
authors.forename: Lars P J
authors.initials: LP
authors.lastname: Cruysberg
authors.forename: Rudy M M A
authors.initials: RM
authors.lastname: Nuijts
authors.forename: Dayle H
authors.initials: DH
authors.lastname: Geroski
authors.forename: Leo H
authors.initials: LH
authors.lastname: Koole
authors.forename: Fred
authors.initials: F
authors.lastname: Hendrikse
authors.forename: Henry F
authors.initials: HF
authors.lastname: Edelhauser
mesh_terms: D020099:Coated Materials, Biocompatible; D003287:Contrast Media / Q000493:pharmacokinetics*; D003907:Dexamethasone / Q000493:pharmacokinetics*; D004338:Drug Combinations; D016503:Drug Delivery Systems / Q000295:instrumentation*; D019793:Fluorescein / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D005938:Glucocorticoids / Q000493:pharmacokinetics*; D006801:Humans; D066298:In Vitro Techniques; D008727:Methotrexate / Q000493:pharmacokinetics*; D008875:Middle Aged; D010539:Permeability; D012235:Rhodamines / Q000493:pharmacokinetics*; D012590:Sclera / Q000378:metabolism*
chemical_list: D020099:Coated Materials, Biocompatible; D003287:Contrast Media; D004338:Drug Combinations; D005456:Fluorescent Dyes; D005938:Glucocorticoids; D012235:Rhodamines; C026188:rhodamine 6G; D003907:Dexamethasone; D019793:Fluorescein; D008727:Methotrexate