title: In vitro cytotoxic effects of benzalkonium chloride in corticosteroid injection suspension.
abstract: BACKGROUND
  Some deleterious effects on cartilage and even severe arthropathy have been reported after intra-articular corticosteroid injections. The objective of the present in vitro study was to determine if an injectable corticosteroid suspension is toxic to articular chondrocytes and synovial cells.
  
  
  METHODS
  Human and bovine articular chondrocytes, bovine synovial cells, mouse C3H10T1/2 cells, and human osteosarcoma MG-63 cells were treated for thirty minutes in monolayer or suspension culture with an injectable corticosteroid suspension or its chemical components, including betamethasone sodium phosphate, betamethasone acetate, and benzalkonium chloride (as preservative). Cell viability was determined by means of microscopy or flow cytometry analysis.
  
  
  RESULTS
  In monolayer culture, the betamethasone corticosteroids per se did not cause cell death, whereas benzalkonium chloride caused death of articular chondrocytes. In suspension culture, betamethasone sodium phosphate at dosages of as high as 6 mg/mL did not cause significant death of human or bovine articular chondrocytes (p > 0.05). In contrast, benzalkonium chloride caused a death rate of 10.6% in human articular chondrocytes at a dosage of 10 microg/mL (p < 0.01), 21.0% at a dosage of 13.3 microg/mL (p < 0.01), and 99.3% and 99.4% at dosages of 20 and 200 microg/mL, respectively (p < 0.001 for both). Similarly, benzalkonium chloride caused death of bovine articular chondrocytes, bovine synovial cells, C3H10T1/2 cells, and MG-63 cells in a dose-dependent manner. When treated with a combination of betamethasone sodium phosphate and 200 microg/mL benzalkonium chloride, >99% of human or bovine articular chondrocytes were dead (p < 0.001).
  
  
  CONCLUSIONS
  The injectable corticosteroid suspension caused death in in vitro culture of human and bovine articular chondrocytes as well as bovine synovial cells because of its preservative benzalkonium chloride. The betamethasone corticosteroids per se did not cause significant chondrocyte death under the conditions tested.
authors.affiliation: Tulane Institute of Sports Medicine, Department of Orthopaedic Surgery, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Davis
authors.forename: Mathew
authors.initials: M
authors.lastname: Cyriac
authors.forename: Dongxia
authors.initials: D
authors.lastname: Ge
authors.forename: Zongbing
authors.initials: Z
authors.lastname: You
authors.forename: Felix H
authors.initials: FH
authors.lastname: Savoie
mesh_terms: D000818:Animals; D001548:Benzalkonium Compounds / Q000009:adverse effects* / Q000494:pharmacology; D001623:Betamethasone / Q000494:pharmacology*; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects* / Q000494:pharmacology; D013583:Synovial Membrane / Q000166:cytology / Q000187:drug effects*
chemical_list: D001548:Benzalkonium Compounds; D005938:Glucocorticoids; D011310:Preservatives, Pharmaceutical; D001623:Betamethasone