Dibucaine (Cinchocaine) HCl is one of the most potent and toxic of the long-acting local anesthetics. [1] Dibucaine (Cinchocaine) HCl blocks both the initiation and conduction of nerve impulses by decreasing the neuronal membrane's permeability to sodium ions. This reversibly stabilizes the membrane and inhibits depolarization, resulting in the failure of a propagated action potential and subsequent conduction blockade. [2]