title: The cytotoxicity of bupivacaine, ropivacaine, and mepivacaine on human chondrocytes and cartilage.
abstract: BACKGROUND
  Intraarticular injections of local anesthetics are frequently used as part of multimodal pain regimens. However, recent data suggest that local anesthetics affect chondrocyte viability. In this study, we assessed the chondrotoxic effects of mepivacaine, ropivacaine, and bupivacaine. We hypothesized that specific cytotoxic potencies directly correlate with analgesic potencies, and that cytotoxic effects in intact cartilage are different than in osteoarthritic tissue.
  
  
  METHODS
  Human articular chondrocytes were exposed to equal and equipotent concentrations of bupivacaine, ropivacaine, and mepivacaine for 1 hour. Cell viability, apoptosis, and necrosis were determined at predefined time points using flow cytometry, live-dead staining, and caspase detection. Intact and osteoarthritic human cartilage explants were treated with equipotent concentrations of named drugs to determine cell viability applying fluorescence microscopy.
  
  
  RESULTS
  Chondrotoxic effects increased from ropivacaine to mepivacaine to bupivacaine in a time-dependent and concentration-dependent manner. Compared with control, bupivacaine 0.5% decreased chondrocyte viability to 78% ± 9% (P = 0.0183) 1 hour and 16% ± 10% (P < 0.0001) 24 hours later, as determined by live-dead staining in monolayer cultures. Viability rates were reduced to 80% ± 7% (P = 0.0475) 1 hour and 80% ± 10% (P = 0.0095) 24 hours after treatment with ropivacaine 0.75%. After exposure to mepivacaine 2%, viable cells were scored 36% ± 6% (P < 0.0001) after 1 hour and 30% ± 11% (P < 0.0001) after 24 hours. Ropivacaine treatment was less chondrotoxic than bupivacaine (P = 0.0006) and mepivacaine exposure (P = 0.0059). Exposure to concentrations up to 0.25% of bupivacaine, 0.5% of ropivacaine, and 0.5% of mepivacaine did not reveal significant chondrotoxicity in flow cytometry. However, chondrotoxicity did not correlate with potency of local anesthetics. Immediate cell death was mainly due to necrosis followed by apoptosis. Cellular death rates were clearly higher in osteoarthritic compared with intact cartilage after bupivacaine, mepivacaine, and ropivacaine treatment in a decreasing order.
  
  
  CONCLUSIONS
  Bupivacaine, ropivacaine, and mepivacaine are chondrotoxic in a time-dependent, concentration-dependent, and drug-dependent manner. Chondrotoxic and analgesic potencies do not directly correlate. Cellular death rates were higher in osteoarthritic compared with intact cartilage after local anesthetic treatment.
authors.affiliation: Department of Anesthesiology, University Medical Center Regensburg, 93042 Regensburg, Germany. Anita.Breu@ukr.de
authors.forename: Anita
authors.initials: A
authors.lastname: Breu
authors.forename: Katharina
authors.initials: K
authors.lastname: Rosenmeier
authors.forename: Richard
authors.initials: R
authors.lastname: Kujat
authors.forename: Peter
authors.initials: P
authors.lastname: Angele
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zink
mesh_terms: D000328:Adult; D000577:Amides / Q000627:therapeutic use / Q000633:toxicity*; D000779:Anesthetics, Local / Q000627:therapeutic use / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D002045:Bupivacaine / Q000627:therapeutic use / Q000633:toxicity*; D002356:Cartilage / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D008619:Mepivacaine / Q000627:therapeutic use / Q000633:toxicity*; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009336:Necrosis; D010003:Osteoarthritis / Q000188:drug therapy / Q000473:pathology; D000077212:Ropivacaine; D013997:Time Factors
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D008619:Mepivacaine; D020169:Caspases; D002045:Bupivacaine