Final answer:
The most common cause of death in a TCA overdose is cardiac arrhythmias due to the cardiotoxic effects of these medications, along with hypotension and sedation as contributing factors.
Step-by-step explanation:
The most common cause of death in Tricyclic Antidepressant (TCA) overdose, such as amitriptyline, is primarily due to their cardiotoxic effects. These drugs inhibit the reuptake of neurotransmitters, with a particular impact on epinephrine and serotonin. The presence of excessive amounts of these neurotransmitters can lead to severe cardiac arrhythmias, which are often the cause of fatality in these cases. Furthermore, TCAs can also cause a significant drop in blood pressure, and sedation, which may contribute to their lethality in overdose situations.
It is important to note that TCAs are no longer as commonly prescribed due to their side effect profiles and the risk associated with overdose. While TCAs can be beneficial for treating major depression, their potential for fatal overdose has been a significant concern in psychopharmacology, leading to the development and preference for medications with safer side effect profiles.