Core pharmacology

Class Group

Antidepressant - Tricyclic anti-depressants

Legacy Cicm Level

Level 3

Mechanism of action

Competitively inhibit neuronal uptake (uptake 1) of noradrenaline and serotonin, thereby increasing their concentrations in the synapse

Additional:
1. Antimuscarinic
2. Antihistamine
Alpha-adrenoreceptor antagonism

Adverse Effects Toxicity

1. Initially increase suicidality in youth
2. CNS- sedation (H1), seizures
3. Anti-Ach: dry mouth, constipation, urinary retention, blurred vision
CVS- postural hypotension

OVERDOSE:
1. CVS
- Sinus tachy
- QT prolongation
- QRS prolongation VT/VF (Sodium channel blockade)
- RBBB
- Labile BP
2. CNS
- Excitation and seizures then depression
3. Mydriasis, hyperthermia

Treatment:
1. Benzos for seizures
2. Hyperventilation and sodium bicarbonate if QRS prolonged
Avoid inotropes if possible

Absorption

Well-absorbed PO with high first pass.

Distribution

Very lipid soluble

Protein binding

Highly protein bound

Metabolism

Hepatic phase 1 and 2 metabolism

Excretion

Renal excretion

Half-life

T1/2= 30-45 hours