title: Evaluation of the cytotoxic effects of ophthalmic solutions containing benzalkonium chloride on corneal epithelium using an organotypic 3-D model.
abstract: BACKGROUND
  Benzalkonium chloride (BAC) is a common preservative used in ophthalmic solutions. The aim of this study was to compare the cytotoxic effects of BAC-containing ophthalmic solutions with a BAC-free ophthalmic solution using an organotypic 3-dimensional (3-D) corneal epithelial model and to determine the effects of latanoprost ophthalmic solution and its BAC-containing vehicle on corneal thickness in a monkey model.
  
  
  METHODS
  The cytotoxicity of commercially available BAC-containing ophthalmic formulations of latanoprost (0.02% BAC) and olopatadine (0.01% BAC) was compared to that of BAC-free travoprost and saline in a corneal organotypic 3-D model using incubation times of 10 and 25 minutes. To compare the extent of differentiation of 3-D corneal cultures to monolayer transformed human corneal epithelial (HCE-T) cell cultures, expression levels (mRNA and protein) of the corneal markers epidermal growth factor receptor, transglutaminase 1 and involucrin were quantified. Finally, latanoprost ophthalmic solution or its vehicle was administered at suprapharmacologic doses (two 30 microL drops twice daily in 1 eye for 1 year) in monkey eyes, and corneal pachymetry was performed at baseline and at weeks 4, 13, 26 and 52.
  
  
  RESULTS
  In the 3-D corneal epithelial culture assays, there were no significant differences in cytotoxicity between the BAC-containing latanoprost and olopatadine ophthalmic solutions and BAC-free travoprost ophthalmic solution at either the 10- or 25-minute time points. The 3-D cultures expressed higher levels of corneal epithelial markers than the HCE-T monolayers, indicating a greater degree of differentiation. There were no significant differences between the corneal thickness of monkey eyes treated with latanoprost ophthalmic solution or its vehicle (both containing 0.02% BAC) and untreated eyes.
  
  
  CONCLUSIONS
  The lack of cytotoxicity demonstrated in 3-D corneal cultures and in monkey studies suggests that the levels of BAC contained in ophthalmic solutions are not likely to cause significant direct toxicity to epithelium of otherwise normal corneas.
authors.affiliation: Drug Safety Research and Development, Pfizer Inc, San Diego, CA 92121, USA. su.khoh-reiter@pfizer.com
authors.forename: Su
authors.initials: S
authors.lastname: Khoh-Reiter
authors.forename: Bart A
authors.initials: BA
authors.lastname: Jessen
mesh_terms: D000818:Animals; D018926:Anti-Allergic Agents / Q000009:adverse effects; D000959:Antihypertensive Agents / Q000009:adverse effects; D001548:Benzalkonium Compounds / Q000008:administration & dosage / Q000009:adverse effects*; D002460:Cell Line; D003008:Cloprostenol / Q000009:adverse effects / Q000031:analogs & derivatives; D003990:Dibenzoxepins / Q000009:adverse effects; D004341:Drug Evaluation; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D000077338:Latanoprost; D008252:Macaca fascicularis; D008954:Models, Biological; D000069605:Olopatadine Hydrochloride; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000009:adverse effects*; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage / Q000009:adverse effects*; D011461:Prostaglandins F, Synthetic / Q000009:adverse effects; D013997:Time Factors; D000069557:Travoprost
chemical_list: D018926:Anti-Allergic Agents; D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D003990:Dibenzoxepins; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D011461:Prostaglandins F, Synthetic; D000069605:Olopatadine Hydrochloride; D003008:Cloprostenol; D000077338:Latanoprost; D000069557:Travoprost