title: Topical Application of Naltrexone to the Ocular Surface of Healthy Volunteers: A Tolerability Study.
abstract: OBJECTIVE
  A short-term, randomized double-masked study was conducted to test the tolerability of topical application of naltrexone to the corneal surface.
  
  
  METHODS
  Healthy human volunteers were recruited at the Penn State Hershey Medical Center between 2010 and 2013. Study groups of 4 subjects were established to receive escalating dosages of naltrexone; within each group, 1 subject received placebo. Four drops of 4 different dosages of naltrexone dissolved in commercial moxifloxacin solution were administered over a 24-h period of time; 1 group of subjects received only 1 drop. The naltrexone dosages tested were 1 × 10(-6) M (1 drop), 1 × 10(-6) M (4 drops), 5 × 10(-6) M (4 drops), 1 × 10(-5) M (4 drops), and 5 × 10(-5) M (4 drops). Drops were administered over a 24-h period. Consenting subjects had complete eye examinations, including visual acuity (ETDRS), external and slit-lamp examinations, corneal sensitivity, pachymetry, corneal topography, endothelial specular microscopy, Schirmer testing with anesthetic, and fundus photography, before receiving naltrexone. Individuals were reexamined at 24 h and 7 days following naltrexone or placebo application.
  
  
  RESULTS
  Twenty subjects were recruited for the study; 62% were male, 90% were Caucasian; and 19 subjects completed the study. No significant differences were noted in ocular health between left (treated) and right (untreated) eyes of subjects receiving naltrexone or placebo. No significant adverse events were reported.
  
  
  CONCLUSIONS
  Topical naltrexone was well tolerated in healthy human subjects after 1 or 4 eye drops of naltrexone at dosages up to 50 μM administered over a 24-h treatment period and observed for 1 week.
authors.affiliation: 1 Department of Ophthalmology, Pennsylvania State University College of Medicine , Hershey, Pennsylvania.
authors.forename: David
authors.initials: D
authors.lastname: Liang
authors.affiliation: 1 Department of Ophthalmology, Pennsylvania State University College of Medicine , Hershey, Pennsylvania.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Sassani
authors.affiliation: 2 Department of Neural & Behavioral Sciences, Pennsylvania State University College of Medicine , Hershey, Pennsylvania.
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: McLaughlin
authors.affiliation: 2 Department of Neural & Behavioral Sciences, Pennsylvania State University College of Medicine , Hershey, Pennsylvania.
authors.forename: Ian S
authors.initials: IS
authors.lastname: Zagon
mesh_terms: D060433:Administration, Ophthalmic; D000287:Administration, Topical; D000328:Adult; D004311:Double-Blind Method; D005128:Eye Diseases / Q000188:drug therapy*; D005260:Female; D005500:Follow-Up Studies; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009271:Naltrexone / Q000008:administration & dosage / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D011379:Prognosis; D055815:Young Adult
chemical_list: D009292:Narcotic Antagonists; D009271:Naltrexone