Abstract
The effects of verapamil and naloxone as potential antidotes for amitrlptyline-lnduced cardlotoxlcity were Investigated in an experimental rat model. Amitrlptyline was infused continuously at a dose of 37.5 mg/kg/h. After 15 minutes, the animals were given either naloxone (2 mg/kg + 3 mg/kg/h), verapamil (0.08 mg/kg + 0.08 mg/kg/h), or physiological saline.
In the group given naloxone, a significant decrease in heart rate was seen. Although MAP and max dP/dT increased, there was no significant difference from controls. Naloxone did not decrease mortality. When the bolus dose of verapamil was given, a significant decrease in MAP and max dP/dT was obtained. Although the mean blood pressure was significantly higher in those animals treated with verapamil who survived 60 minutes, verapamil did not change the course of the amitrlptyline poisoning. In conclusion, our findings indicate that naloxone lacks significant positive effects and that verapamil has an additional negative inotroplc effect. Neither drug can be recommended for the treatment of amitriptyline poisoning.