Do tricyclic antidepressants cause cardiotoxicity?
Abstract. Tricyclic antidepressants remain a common cause of fatal drug poisoning as a result of their cardiovascular toxicity manifested by ECG abnormalities, arrhythmias and hypotension.
How does TCA cause cardiotoxicity?
The cardiotoxic effects of TCA are mediated by inhibition of the sodium channels which slows depolarization in the myocardium and conducting tissues. As a result, there is prolongation of QRS complex, PR and QT intervals5,6. Various EKG abnormalities may predict complications in cases of TCA overdose.
How do tricyclic antidepressants affect heart?
2 The TCAs have important effects on the heart, related to their anticholinergic and quinidine-like properties. The major side effects in therapeutic dosage include heart rate increase, postural hypotension and slight prolongation of the intraventricular conduction time and QT interval.
Can TCA cause cardiac arrhythmias?
Tricyclic antidepressant overdose is widely felt to be associated with cardiac arrhythmias which may occur without warning, sometimes late in the clinical course. For this reason, many institutions routinely monitor cardiac rhythm in such patients for up to 72 h.
Why do tricyclic antidepressants cause seizures?
They also block alpha receptors peripherally and thus can cause hypotension. Furthermore, they block neurotransmitter reuptake (norepinephrine, serotonin) at central presynaptic terminals, and this may be the mechanism by which seizures are induced by TCA overdose.
What drugs are tricyclic antidepressants?
The Food and Drug Administration (FDA) approved these tricyclic antidepressants to treat depression:
- Desipramine (Norpramin)
- Imipramine (Tofranil)
- Nortriptyline (Pamelor)
Why TCA cause metabolic acidosis?
The amount of unbound tricyclic may also increase if the overdose causes respiratory depression resulting in an acidosis, which reduces protein binding. The toxic effects of tricyclics are caused by four main pharmacological properties: Inhibition of norepinephrine reuptake at nerve terminals.
What is the role of lidocaine or phenytoin in tricyclic antidepressant induced cardiotoxicity?
It is postulated that lidocaine’s rapid binding to the sodium channel may directly displace slower acting agents from the channel, leaving more channels unbound, and therefore be able to facilitate cardiac conduction.
Who should not take tricyclic antidepressants?
Ask your doctor before taking TCAs if you:
- Are under age 25 or over age 65.
- Have diabetes, heart problems, or a thyroid disorder.
- Have any conditions affecting your urinary tract or an enlarged prostate.
- Have glaucoma.
- Have a liver disease.
- Have a history of seizures.
- Take medications to help manage your mood.
What are the side effects of tricyclic antidepressants?
Some common possible side effects include:
- Blurred vision.
- Dry mouth.
- Drop in blood pressure when moving from sitting to standing, which can cause lightheadedness.
- Urine retention.
What meds are tricyclic antidepressants?
Why are tricyclic antidepressants so toxic in overdose?
TCAs are rapidly absorbed in the gastrointestinal tract. However, following an overdose, owing to the inherent anticholinergic effects, TCAs may decrease the gastrointestinal motility and cause delayed absorption and toxicity. Coingestion of other anticholinergic medications may cause more erratic absorption.