ABSTRACT
Antioxidants play an important role in protecting cardiac arrhythmias. Silymarin, strong antioxidant, is effective in reducing the complications caused by arrhythmias. This study was conducted to determine the effect of silymarin on the prevention and treatment of calcium chloride-induced arrhythmia. In total, 48 male rats were randomly divided into six groups: the first control group for acute administration received intravenous injection of 0.2 mL of dimethylsulfoxide, a cosolvent, immediately after induction of arrhythmia; the second control group for chronic administration, daily gavage of dimethylsulfoxide for 2 weeks before induction of arrhythmia; acute silymarin group, 100 mg/kg intravenous, immediately after the occurrence of arrhythmia; chronic silymarin group, daily gavage of 50 mg/kg for 2 weeks before induction of arrhythmia; amiodarone standard treatment, 5 mg/kg intravenous, immediately after induction of arrhythmia; and quinidine standard treatment, 10 mg/kg intravenous, immediately after induction of arrhythmia. Calcium chloride (140 mg/kg, i.v.) was used to induce arrhythmia. Electrocardiogram was recorded and monitored by PowerLab™ system. The incidence rates of premature ventricular beat (PVB), ventricular tachycardia (VT), and ventricular fibrillation (VF) were calculated. The antiarrhythmic effect of silymarin was observed with a significant decrease in the incidence of premature ventricular beat (22.56 ± 1.04%, P < 0.001), ventricular tachycardia (34.150 ± 1.59%, P < 0.001), and ventricular fibrillation (24.31 ± 1.02%, P < 0.001) compared with the control group (100%). These effects were comparable to antiarrhythmic drugs such as quinidine (29.23% ± 1.24%, 52.23% ± 1.13%, 66.31% ± 1.81%) and amiodarone (22.91% ± .72%, 41.09% ± 1.66%, 61.59% ± 1.11%). Silymarin exerts a potent antioxidant effect, thereby mitigating the risk of VT, VF, and PVC.