title: Effects of benzalkonium chloride- or polyquad-preserved fixed combination glaucoma medications on human trabecular meshwork cells.
abstract: OBJECTIVE
  We investigated the potential short and long-term effects in cultured human trabecular meshwork (TM) cells of various topical glaucoma formulations containing different preservatives.
  
  
  METHODS
  We tested the fixed combination medications 0.004% travoprost plus 0.5% timolol preserved with either 0.015% benzalkonium chloride (BAK; DuoTrav®), or with 0.001% polyquad (PQ; DuoTrav(®) BAK-free); and 0.005% latanoprost plus 0.5% timolol preserved with 0.020% BAK (Xalacom(®)). Also tested was a range of BAK concentrations (0.001%-0.020%) in balanced salt solution (BSS). Cells were treated for 25 min at 37 °C with solutions diluted 1:10 and 1:100 to mimic the reduced penetration of topical preparations to the anterior chamber. The percentage of live cells was determined immediately after treatment through the uptake of the fluorescent vital dye calcein-AM. To determine any long-term effects, we assayed release of matrix metalloproteinase 9 (MMP-9) and apoptosis 24 h after treatments.
  
  
  RESULTS
  BAK demonstrated a dose-dependent reduction in TM cell viability, ranging from 71±5% live cells at 0.001% BAK (diluted 1:10) to 33±3% live cells at 0.020% BAK (diluted 1:10). Travoprost (0.004%) plus 0.5% timolol preserved with 0.015% BAK had statistically fewer live TM cells (79±7%) than the same preparation preserved with 0.001% polyquad® (PQ; 93±1%; p<0.001). Latanoprost plus timolol preserved with 0.020% BAK (29±9% live cells) was similar to the 0.020% BAK (33±3%) treatment. However, travoprost plus timolol preserved in 0.015% BAK had significantly more live cells (83±12%) than the 1:10 dilution of 0.015% BAK (49±10%). We also found 0.020% BAK (diluted 1:100) resulted in elevated levels of extracellular MMP-9 at 24 h.
  
  
  CONCLUSIONS
  These results demonstrate that the substitution of the preservative BAK from topical ophthalmic drugs results in greater in vitro viability of TM cells. Travoprost with timolol, but not latanoprost with timolol, countered some of the toxic BAK effects. BAK treatment appeared to cause elevated levels of MMP-9, a matrix metalloproteinase implicated in the pathogenesis of glaucoma.
authors.affiliation: University of Colorado Hospital Eye Center, University of Colorado Denver, Department of Ophthalmology, Aurora, CO 80045, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Ammar
authors.forename: Malik Y
authors.initials: MY
authors.lastname: Kahook
mesh_terms: D000959:Antihypertensive Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001548:Benzalkonium Compounds / Q000009:adverse effects* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D003008:Cloprostenol / Q000031:analogs & derivatives / Q000494:pharmacology; D004338:Drug Combinations; D005452:Fluoresceins / Q000378:metabolism; D005901:Glaucoma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D000077338:Latanoprost; D020780:Matrix Metalloproteinase 9 / Q000032:analysis / Q000378:metabolism; D011108:Polymers / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects* / Q000494:pharmacology; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology; D013999:Timolol / Q000494:pharmacology; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects*; D000069557:Travoprost
chemical_list: D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D004338:Drug Combinations; D005452:Fluoresceins; D011108:Polymers; D011310:Preservatives, Pharmaceutical; D011461:Prostaglandins F, Synthetic; C085925:calcein AM; D003008:Cloprostenol; D000077338:Latanoprost; C058655:polyquaternium 1; D013999:Timolol; D020780:Matrix Metalloproteinase 9; D000069557:Travoprost