Effects of local anesthetics on cell growth and colony formation of human thyroid cancer cells.

<p>(<b>A</b>) 8505C and K1 cells were treated with serial dilutions of lidocaine and bupivacaine, individually or in combinations, for 24 and 48 h. Error bars represent standard error of the mean. (<b>B</b>) A conservative isobologram demonstrates that lidocaine and bupivacaine acts antagonistically to inhibit the cell growth of thyroid cancer cells. ED indicates effective dose. The ED50 (red X), ED75 (green crosses), and ED90 (blue circles) are graphed. (<b>C</b>) Treatment with lidocaine and bupivacaine resulted in reduction of colony formation of the 8505C and K1 cell lines. Error bars represent standard error of the mean. *, P<0.01 <i>versus</i> control.