Effects of magnesium sulfate and lidocaine in the treatment of ventricular arrhythmias in experimental amitriptyline poisoning in the rat.
OBJECTIVE
Amitriptyline poisoning is associated with ventricular arrhythmias. Standard treatment is sodium bicarbonate but further intervention may be necessary. The present study compared the actions of lidocaine and magnesium sulfate on ventricular tachycardia induced by amitriptyline.


METHODS
Nonrandomized, controlled, intervention trial.


METHODS
University laboratory.


METHODS
Thirty male Wistar rats anesthetized with pentobarbital and mechanically ventilated.


METHODS
After pretreatment with norepinephrine, the animals were subjected to a continuous infusion of amitriptyline. After the appearance of ventricular tachycardia, they were treated with magnesium sulfate (45 mg/kg + 15 mg/kg/min) or lidocaine (1 mg/kg + 0.5 mg/kg/min) or glucose infusion as a control.


RESULTS
In the group treated with magnesium sulfate, electrocardiogram tracings demonstrated that nine of ten animals converted from ventricular tachycardia to sinus rhythm compared with one of ten in both the lidocaine- and glucose-treated groups (p < .001). The animals treated with magnesium sulfate also had a significantly longer total time in sinus rhythm (10.0 +/- 1.6 mins) than those rats treated with lidocaine (1.7 +/- 1.5 mins) or glucose (1.5 +/- 1.5 mins). Magnesium sulfate significantly decreased blood pressure and heart rate, but no severe hemodynamic side effects were observed.


CONCLUSIONS
Magnesium sulfate is effective in converting ventricular tachycardia in hyperadrenergic amitriptyline poisoning. In contrast, lidocaine had no effect on arrhythmias.
Knudsen
K
K
Department of Anesthesia and Intensive Care, University of Göteborg, Sweden.
Abrahamsson
J
J
D000639:Amitriptyline / Q000506:poisoning*; D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004562:Electrocardiography / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D008012:Lidocaine / Q000627:therapeutic use*; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017180:Tachycardia, Ventricular / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology
D000639:Amitriptyline; D008278:Magnesium Sulfate; D008012:Lidocaine