title: Topical fentanyl in a randomized, double-blind study in patients with corneal damage.
abstract: OBJECTIVE
  Corneal damage causes severe pain. This study investigated whether peripheral opioid receptors are present in the human cornea and assessed the efficacy of topical fentanyl in patients with corneal erosion.
  
  
  METHODS
  Immunohistochemical staining experiments were performed to examine the presence of both mu and delta-receptors on peripheral nerve fibers within human corneal tissue. In a randomized, double-blind clinical trial dexpanthenol (n=20) or dexpanthenol plus 10 microg fentanyl (n=20) were topically applied every 4 hours to the eye of patients with a surgical intervention of corneal damage and subjective pain intensity was determined by a numerical rating scale.
  
  
  RESULTS
  Immunohistochemical staining identified peripheral nerve fibers in human cornea expressing both mu and delta-opioid receptors. In patients with corneal damage the ophthalmic intervention in local anesthesia decreased the subjective pain intensity significantly. At 4-hour intervals after the ophthalmic intervention, moderate pain intensity levels were not altered by the application of dexpanthenol with or without fentanyl. At 24 hours pain intensity dropped significantly, most likely owing to a natural decrease in pain, because the erosion was almost healed.
  
  
  CONCLUSIONS
  Both mu and delta-receptors are localized on nerve fibers within the cornea, which are accessible for topical opioid treatment. However, our formulation and dose of topical fentanyl in combination with dexpanthenol did not show any benefit in relieving pain from corneal erosion. Future studies are planned to determine the optimal protocol and dose of topical opioid treatment.
authors.affiliation: Klinik für Anaesthesiologie und Operative Intensivmedizin, Charité Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany. christian.zoellner@charite.de
authors.forename: Christian
authors.initials: C
authors.lastname: Zöllner
authors.forename: Shaaban
authors.initials: S
authors.lastname: Mousa
authors.forename: Astrid
authors.initials: A
authors.lastname: Klinger
authors.forename: Michael
authors.initials: M
authors.lastname: Förster
authors.forename: Michael
authors.initials: M
authors.lastname: Schäfer
mesh_terms: D000287:Administration, Topical; D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D003316:Corneal Diseases / Q000188:drug therapy* / Q000378:metabolism; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005283:Fentanyl / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010205:Pantothenic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D017465:Receptors, Opioid, delta / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000378:metabolism; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D010205:Pantothenic Acid; C007288:dexpanthenol; D005283:Fentanyl