[Drug-induced psychiatric disturbance by lidocaine].

Lidocaine is widely used as an antiarrhythmic agent. One of the side effects of lidocaine is disorientation. Measurement was made of the plasma level of lidocaine in twelve consecutive cases. Lidocaine infusion had been given to these cases for more than twenty-four hours. Measurements were then made of the frequency of psychiatric disturbance. Psychiatric disturbances were recognised in six cases and the plasma levels in four cases among them were more than 5 micrograms.ml-1. The psychiatric disturbances disappeared within three hours after the cessation of lidocaine infusion. When disorientation occurs in a patient who receives lidocaine treatment, drug-induced psychiatric disturbance should be suspected.