title: The cytotoxic effects of preserved and preservative-free prostaglandin analogs on human corneal and conjunctival epithelium in vitro and the distribution of benzalkonium chloride homologs in ocular surface tissues in vivo.
abstract: OBJECTIVE
  To investigate the cytotoxicity of benzalkonium chloride (BAC)-containing ophthalmic solutions of prostaglandin analogs (latanoprost, travoprost, bimatoprost, and preservative-free (PF) tafluprost), BAC mixture (BACmix) and BAC homologs with different alkyl chain lengths using human corneal epithelial (HCE) and conjunctival epithelial (IOBA-NHC) cell cultures. The distribution of BAC homologs in rabbit ocular surface tissues in vivo was examined.
  
  
  METHODS
  The cells were exposed for one hour to prostaglandin analogs, BACmix and three homologs. Cytotoxicity was assessed with the WST-1 and lactate dehydrogenase (LDH) assays for cellular viability and cell membrane integrity. BAC 0.02% solution was instilled on the rabbit eye daily for 14 days and the concentrations of BAC homologs in external ocular tissues were determined.
  
  
  RESULTS
  The order of decreasing cytotoxicity in the WST-1 test was latanoprost ≥ travoprost > bimatoprost ≥ PF tafluprost. IOBA-NHC cells were more sensitive than HCE cells. In HCE, only latanoprost diluted to 10% increased LDH leakage. In IOBA-NHC, LDH leakage was statistically significant with 3-10% travoprost and 10% latanoprost. The order of decreasing cytotoxicity of preservatives was C14 > C12 > BACmix > C16 in HCE and C12 > C14 > BACmix > C16 in IOBA-NHC. Following treatment with BAC 0.02% solution, the amounts of BAC-C12, -C14 and -C16 in rabbit cornea and conjunctiva, respectively were: 0.37 ± 0.08 and 2.64 ± 0.27 ng/mg; 0.42 ± 0.07 and 4.77 ± 0.43 ng/mg; 0.04 ± 0.01 and 0.54 ± 0.05 ng/mg.
  
  
  CONCLUSIONS
  The cytotoxic effects of latanoprost, travoprost, and bimatoprost were dependent on the BAC concentration in their formulations. BACmix was cytotoxic at the concentrations above those corresponding to 0.001% BAC in ophthalmic medications. PF tafluprost was the least toxic of the drugs tested. Within studied BAC homologs, those with longer alkyl chain and higher lipophility penetrated effectively into rabbit external ocular tissues.
authors: Santen Oy, Tampere, Finland. pertti.pellinen@santen.fi
authors: Pertti
authors: P
authors: Pellinen
authors: Anne
authors: A
authors: Huhtala
authors: Ari
authors: A
authors: Tolonen
authors: Jukka
authors: J
authors: Lokkila
authors: Jukka
authors: J
authors: Mäenpää
authors: Hannu
authors: H
authors: Uusitalo
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000633:toxicity*; D001548:Benzalkonium Compounds / Q000493:pharmacokinetics / Q000633:toxicity*; D002460:Cell Line; D002470:Cell Survival; D003228:Conjunctiva / Q000187:drug effects* / Q000378:metabolism; D004848:Epithelium; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical / Q000493:pharmacokinetics / Q000633:toxicity*; D011461:Prostaglandins F, Synthetic / Q000633:toxicity*; D011817:Rabbits; D014018:Tissue Distribution
chemical_list: D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D011461:Prostaglandins F, Synthetic; D007770:L-Lactate Dehydrogenase