This document discusses tricyclic antidepressant (TCA) toxicity. It notes that TCAs have been used to treat depression since the 1950s and are the largest group of drug agents used for this purpose. The document outlines different types of TCA drugs and their mechanisms of action. It describes the cardiovascular, central nervous system, and peripheral manifestations of TCA toxicity. The document provides details on physical exam findings, laboratory studies, imaging, ECG patterns, and treatment for TCA toxicity.

1. TCA TOXICITY
Ehsan hasanpour
10/27/2018

2. Tricyclic antidepressant :
They have been employed in drug therapy since the
late 1950s.
Largest group of drug agents used for the treatment
of depression.
Referred as “ tri cyclic ” compounds –three rings.
Third most common cause of drug related death in
US throughout 1980s

3. TCA Drugs :
 Secondary amines: -Amoxapine ,
Nortriptyline , Desipramine , Protriptyline.
 Tertiary amines:- Amitriptyline ,
Imipramine,Doxepin,Trimipramine.
 Tetra cyclic:- Maprotiline.
 Triazolopyridine :-Trazodone.

4. Mechanism :
 Decreases the action of acetylcholine centrally and
peripherally.
 Enhances dopamine levels.
 Reduced serotonin and norepinephrine uptake resultant
increase within the synapse.
 Respiratory dysfunction and disturbances in body temp-
respiratory center ,thermoregulatory site.
 Membrane-stabilizing effect on the myocardium by blocking
the cardiac myocyte fast sodium channels

5. Bioavailability :
 slowly absorbed secondary to ionization in
 the stomach and slowing of peristalsis
 Can remain in gut for 12 hours or more
 Dissolve slowly
 85-98% plasma bound

6. Cardiovascular manifestations of TCA Toxicity :
• Palpitation
• Chest pain
• Hypotension
• Ecg abnormality

7. CNS manifestations of TCA Toxicity :
• Convulsion
• Decrease mental status
• Respiratory depression
• Drowsiness
• Coma

8. Peripheral autonomic system manifestations :
• Dry mouth
• Dry skin
• Urinary retention
• constipation
• Blurred vision

9. Physical exam findings :
• Tachycardia
• Hypotension and orthostasis
• Fever
• Altered mental status
• Ileus
• Absent bowel sounds
• Rigidity
• Dry skin and mucous membranes
• Mydriasis

10. • Electrolyte (Na,K,Cl ,Ca)
• blood urea nitrogen (BUN), and creatinine levels
• Arterial blood gases (ABGs) for evaluation of acidosis
or hypoxia
• Anion gap Complete blood cell count (CBC)
• Blood alcohol level
Laboratory Studies :

11. Imaging Studies:
Chest X Ray
ECG:

12. Brugada Pattern :

13. Treatment :
 25% of cases, patients were alert and awake
 at first prehospital contact
 Immediately evaluate the patient and administer oxygen.
 Monitor vital signs.
 Stabilization : Insert an intravenous line and cardiac
monitoring.
 Altered mental status :naloxone, glucose and if indicated
thiamine.
 Adequate ventilation ,prolonged cardiac massage.
 NO IPECAC (CNS depression can be
 rapid)
 Activated charcoal

14. SUPPORT VITAL FUNCTIONS:
• Respiratory depression : intubation and
hyperventilation
• Hypotension :Nor epinephrine , Phenyl epinephrine,
Sodium bicarbonate , Glucagon(10mg bolus followed
by an infusion of 10 mg over 6 hours) .
• Dysrhythmias: sodium chloride, Sodium bicarbonate
• Convulsion : Diazepam(0.1 mg/kg iv). Phenytoin
infusion (15 mg/kg iv) over 30 min . Benzodiazepines
,Phenobarbital (15-20 mg/kg).