anesthesia & anti depressant drugs

1. Non-anesthetic drugs
(Part 1)
Antidepressant agents
DR.IBRAHIM HASSAAN (,MBCHB,MSC,EDAIC)
13/05/2023

2. classes of antidepressant agents
• Reduced serotonin reuptake: SSRIs, TCAs
• Inhibits serotonin metabolism: MAoIs
◦ MAO-A , moclobemide(selectively breaks down serotonin, epinephrine and norepinephrine)
◦ MAO-B, selegiline (selectively breaks down phenethylamine))
• Increases sensitivity of receptor: Lithium

3. TCA drugs
The mechanism of action of
• Anticholinergic effects
• Competitive antagonism of H1 and H2 receptors
• Blockade of presynaptic uptake of amines (norepinephrine, dopamine, and serotonin)
• Antagonism of α1 adrenergic receptors
• Blockade of the cardiac fast sodium channel
• Blockade of the cardiac delayed rectifier potassium channel

4. the pharmacokinetics of TCA drugs.
Absorption: TCA drugs are well absorbed from the GIT
◦ peak plasma levels occur 2 to 4 hours after ingestion.
Distribution: The large volume of distribution
Metabolism: TCA drugs are metabolized in the liver
Excretion: Renal excretion is low and is usually less than 10%

5. the features of a tricyclic antidepressant (TCA)
drug poisoning
CVS
• Palpitations, chest pain, tachycardia, hypotension
• ECG changes include nonspecific ST or T wave changes, prolongation of QT, PR and QRS
interval, Brugada wave (ST elevation in V1–V3 and right bundle branch block)
CNS
• Agitation, hallucinations, blurred vision, convulsions, hyperreflexia, and coma in severe cases
Peripheral autonomic system
• Dry mouth, dry skin, urinary retention, and pyrexia

6. The management of acute TCAD overdose
ABC approach specific measures
• Preventing gastric absorption with activated charcoal
• Induced alkalemia with sodium bicarbonate as this reduces the amount of free drug in circulation
• Treatment of arrhythmias: Ventricular tachyarrhythmia are treated with blockade and severe Brady
arrhythmias may need pacing
• Treatment of seizures with benzodiazepines
Supportive care in a HDU/ICU setting.
Ventilation may be required for a low GCS.
ECG monitoring is recommended for the first 24 hours

7. serotonin syndrome
It is a spectrum of clinical findings due to excess of serotonin in the CNS.
Classical triad of symptoms
◦ Change in mental status -- agitation, delirium, anxiety, seizures, and hallucinations
◦ Autonomic dysfunction--diaphoresis, hypertension, hyperthermia tachycardia, diarrhea
◦ Neuromuscular excitability--: tremors,muscle rigidity, hyperreflexia,
◦ Others: rhabdomyolysis, acute renal failure

8. Treatment
Stopping all drugs acting on serotonin
• Supportive care such as supplemental oxygen, intravenous fluids, and cardiac monitoring.
• Benzodiazepines for agitation and BP control
• Management of autonomic instability—can use short-acting agents such as esmolol
• Controlling hyperthermia
• Considering serotonin antagonists if available (Cyproheptadine is the serotonin antagonist
that has been used.)