Comparison of ropivacaine and fentanyl toxicity in human fibroblasts

INTRODUCTION Although ropivacaine and fentanyl are commonly administered intra-articularly after knee or shoulder arthroscopy for postoperative pain control, there are no studies investigating the toxicity of ropivacaine and fentanyl on human fibroblasts (hF). MATERIAL AND METHODS Human fibroblasts were seeded in monolayer triple flasks at a density of 10(4) cells/cm(2) and plated into 96 plates at a density of 5000 cells per well. After fully aspirating the culture medium 200 µl of ropivacaine or fentanyl in its corresponding concentration or culture medium only was added to each well. After 30 min ropivacaine or fentanyl was removed and fresh culture medium was added. Fibroblast mitochondrial activity and apoptosis marker level were evaluated after 1 h, 24 h and 7 days. RESULTS We found a significant decrease in mitochondrial activity after 7 days when exposed to 0.5% ropivacaine. Mitochondrial activity after 1 h, 24 h and 7 days was significantly decreased when fibroblasts were exposed to 0.05% fentanyl. Also, a significant decrease in mitochondrial activity was observed 1 h after exposure to 0.025% fentanyl. Cell viability remained unchanged at any other point in time. A significant increase of caspase-3, as a marker of apoptosis, was only present after exposure to 0.5% ropivacaine after 7 days. CONCLUSIONS These data suggest that both drugs have a concentration-dependent effect on mitochondrial activity in hF in vitro. This effect is more pronounced with fentanyl. Because the cytotoxicity of fentanyl, without the anticipated increase of caspase-3 as an apoptosis marker, remains unclear, we cannot support fentanyl as an alternative to ropivacaine.