Electrocardiographic Changes Induced by Ivermectin in Guinea Pigs

Abstract

Guinea pigs were used to observe the possible side effects of ivermectin (500 μg/kg b.w.) on the heart by  recording their electrocardiograms (ECG) at 24, 48 and 72 hours after its injection (experimental groups).  Significant effects of ivermectin on the electrocardiographic parameters belong to limb lead II were compared  to those of the control group. These were: the increases in amplitudes of P, S (only at 24 hours) and  T waves, and also the lengthening (or “prolongation”) in the durations of P and T waves, QRS complex  (only at 24 and 48 hours) and PR and QTc intervals at 24, 48 and 72 hours. As a consequence of the prolonged  durations mentioned above, statistically significant decreases of heart beats were found on the electrocardiograms  recorded at 24 and 48 hours after ivermectin injection (p<0.05). In conclusion, the weak  conductance in the heart of guinea pigs as an indicator of the prolongation in durations and intervals (negatively  dromotropic) induced by ivermectin can be interpreted as its inhibitory effect on the sarcoplasmic  reticulum Ca2+ -ATPase pump causing a late Ca2+ accumulation after systole due to the reduced amount of  Ca2+.