Art.Nr.: 187-PKD-4 Local anesthetics act by blocking voltage-gated sodium channels (rapid influx of sodium), which is important for depolarization. This results in no transmission of the conducted signal. The effect on the ion channel occurs due to the protonated form of the local anesthetic, as a charged molecule. However, the binding site of local anesthetics is on the intracellular side of the sodium channel. In order to diffuse through the cell membrane of the axon, the local anesthetic must be in an unprotonated (uncharged, basic, undissociated) lipophilic form. The molecule dissociates on the intracellular side and changes to the protonated (charged, dissociated) form. The physicochemical properties are therefore of particular importance. Once there, its lipophilic and hydrophilic residue interacts with the amino acids phenylalanine and tyrosine of the sodium channel and thus prevents the channel from opening. The sodium channels are preferably blocked in their inactivated form.
