Basic benzanilides with local anaesthetic activity

Four groups of three isomers structurally related to lidocaine through the vinilogy principle are described and their pharmacological properties evaluated. The new products were obtained introducing an aromatic ring between carbamidic and N-disubstituted aminomethyl groups of the glycinamide chain. This modification allowed the basic group may be located alternatively in the ortho, meta, and para position of the aromatic ring. The ortho isomers were more toxic than the other ones. The evaluation of the local anesthetic potency through surface, infiltration and conduction tests has shown a strict activity-toxicity correlation in each group of isomers. Finally their different potency has been related to the vinilogy principle and to the receptor model of local anaesthetics.