[Antiarrhythmic action of disopyramide: a study of plasma levels]

The action of dysopyramide was studied in 13 patients, 11 with ventricular and 2 with supraventricular arrhythmias. The drug was given parenterally at first and then by mouth. The patients were monitored with an arrhythmia counter and the plasma levels of disopyramide measured throughout the treatment period. The plasma level was stable at about 4 micrograms/ml during the different phases. Toxic levels of 10 microgram/ml were observed in 1 patient in renal failure. The antiarrhythmic action was very effective (70% success), especially on the ventricular arrhythmias. Two of the four patients who failed to respond to treatment had low, non-therapeutic plasma levels. The dosage should be adapted with respect to the patient's weight and renal function.