Comprehensive Nursing Pharmacology Q 34

---

The most serious adverse effect of tricyclic antidepressant (TCA) overdose is:

  

     A. Hyperpyrexia

     B. Cardiac arrhythmias

     C. Seizures

     D. Metabolic acidosis

    

    

Correct Answer: B. Cardiac arrhythmias.

---

Excessive ingestion of TCAs results in life-threatening wide QRS complex tachycardia. Tricyclic antidepressants act on approximately five different neurotransmitter pathways to achieve their effects. They block the reuptake of serotonin and norepinephrine in presynaptic terminals, which leads to increased concentration of these neurotransmitters in the synaptic cleft. The increased concentrations of norepinephrine and serotonin in the synapse likely contribute to its antidepressant effect.

---

Option A: TCAs do not cause an elevation in body temperature. TCAs have varying degrees of receptor affinities, leading to several adverse effects. The most common adverse effects include constipation, dizziness, and xerostomia. Due to its blockade of cholinergic receptors, it can lead to blurred vision, constipation, xerostomia, confusion, urinary retention, and tachycardia.

Option C: TCA overdose can induce seizures, but they are typically not life-threatening. There is evidence of TCAs increasing the risk of seizures in those with epilepsy, and use requires caution in this population.

Option D: TCAs do not cause metabolic acidosis. Due to the blockade of alpha-1 adrenergic receptors, it can cause orthostatic hypotension and dizziness. TCA-induced histamine blockade (H1) may lead to sedation, increased appetite, weight gain, and confusion.

---