title: Bioavailability of fluorescein from a new drug delivery system in human eyes.
abstract: OBJECTIVE
  To assess the ocular bioavailability of fluorescein from a novel drug delivery system compared with one single preservative free eye drop.
  
  
  METHODS
  Part A: In a randomised study 10 volunteers applied the lyophilisate to one eye and a conventional fluorescein eye drop to the fellow eye. Fluorophotometry was performed before and every 2 minutes up to 30 minutes after application in the cornea and anterior chamber. Part B: Another 10 volunteers applied each form of the application. Fluorophotometry was performed before, +2 minutes, and at +8, +10, +12 hours. The dose corresponding to a single fluorescein dose of the lyophilisate was 68 l microg fluorescein SE 0.17%.
  
  
  RESULTS
  Part A: During the first 30 minutes after administration of the preservative free eye drop of 40 microg the corneal and anterior chamber concentration means were up to 16 times higher in eyes treated with the lyophilisate. Part B: 8-12 hours after application the mean fluorescein concentration in the cornea of the lyophilisate group was two times higher than at baseline. Eyes treated with eye drops had baseline values at +8, +10 and +12 hours.
  
  
  CONCLUSIONS
  A significantly better bioavailability was achieved in human eyes by using lyophilisate compared with the same dose from a conventional eye drop. Lyophilisates are a favourable alternative to conventional eye drops since they have no preservatives, higher long term stability, no pH adjustment, and easy handling.
authors.affiliation: Department of Ophthalmology, University of Cologne, Germany. persteinfeld@yahoo.com
authors.forename: A
authors.initials: A
authors.lastname: Steinfeld
authors.forename: A
authors.initials: A
authors.lastname: Lux
authors.forename: S
authors.initials: S
authors.lastname: Maier
authors.forename: R
authors.initials: R
authors.lastname: Süverkrüp
authors.forename: M
authors.initials: M
authors.lastname: Diestelhorst
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000378:metabolism; D001682:Biological Availability; D003315:Cornea / Q000378:metabolism; D004337:Drug Carriers / Q000493:pharmacokinetics; D016503:Drug Delivery Systems; D005123:Eye / Q000378:metabolism*; D005260:Female; D019793:Fluorescein / Q000008:administration & dosage / Q000493:pharmacokinetics*; D015590:Fluorophotometry; D005612:Freeze Drying; D006801:Humans; D008297:Male; D009883:Ophthalmic Solutions
chemical_list: D004337:Drug Carriers; D009883:Ophthalmic Solutions; D019793:Fluorescein