Effect of tocainide on the concentrations of norepinephrine dopamine, serotonin and histamine in rat brain and its binding affinity to neuroceptors.

Tocainide (W-36095, Xylotocan) is a derivative of lidocaine which is applied clinically as a cardiac antiarrhythmic. In addition, it diminishes the severity of symptoms in neurological disorders such as myotonia and paramyotonia and in patients with torticollis spasmodicus it brings about a distinct reduction in the tension of the neck muscles. It was investigated whether in reducing the tonus in torticollis spasmodicus tocainide could be acting on the central nervous system. The binding affinity of the substance to the dopamine, serotonin, opiate, GABA and benzodiazepine receptors was measured without finding any significant affinities. In addition, the effect of tocainide on the concentration of the neurotransmitters norepinephrine (noradrenaline), dopamine, serotonin and histamine were investigated in rat brain, and it was found that tocainide induces a significant increase in dopamine and serotonin concentrations. This lead to the conclusion that, in addition to its antiarrhythmic effects, tocainide acts on the central nervous system.