Amitriptyline

TCA·Psychiatry - Antidepressants

Major Depressive Disorder

PBSTCAEndep10 mg tabletS4+1

Max Dose

150 mg/day

Half-life

20 h

Toxicity in OD

CRITICAL

Anticholinergic

SEVERE

Rapid Summary

Overview

Tricyclic Antidepressant (TCA). The original, 'dirty' but incredibly effective drug. Used rarely for depression now, but heavily utilized in micro-doses for chronic nerve pain and migraine prevention.

Maximum Dose

Max 150 mg/day (Depression). Max 50-75 mg/day (Neuropathic pain).

Clinical Focus

Fatal in overdose. TCAs block cardiac sodium channels causing widening QRS, lethal arrhythmias, and profound anticholinergic coma.

Bottom Line

Amitriptyline is a TCA widely used at low dose for neuropathic pain, migraine prophylaxis, and insomnia, but is cardiotoxic in overdose and has significant anticholinergic burden in elderly.

Formulation & Access

Brand Names

Endep

Oral Routes

Tablets (10 mg, 25 mg, 50 mg).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Major Depressive Disorder.

Off-Label

OFF

Neuropathic pain, migraine prophylaxis, IBS-D, severe insomnia.

Clinical Place

First-line low-dose adjunct for chronic nerve pain (e.g., post-herpetic neuralgia, diabetic neuropathy).

Quick reference

Class & Role

TCA — Tricyclic Antidepressant (TCA).

Route / Formulation

Tablets (10 mg, 25 mg, 50 mg). (Endep)

Usual Dose & Max

Start PO 10-25 mg NOCTE. Titrate up every 1-2 weeks. Target 25-75 mg NOCTE. Max 150 mg/day (Depression).

Key Indication Doses

Neuropathic Pain / Migraine: Start PO 10-25 mg NOCTE. Titrate up every 1-2 weeks. Target 25-75 mg NOCTE. Depression: Start PO 50 mg NOCTE. Titrate to 100-150 mg/day. (Rarely used due to safer SSRIs). Elderly / Frail: Avoid if possible. If required, strictly max 10 mg NOCTE due to severe falls/delirium risk.

Best Uses

Amitriptyline is a TCA widely used at low dose for neuropathic pain, migraine prophylaxis, and insomnia, but is cardiotoxic in overdose and has significant anticholinergic burden in elderly.

Avoid / Cautions

Recent myocardial infarction, heart block, severe hepatic impairment, concurrent MAOIs. Pregnancy Category C.

Key Risks

Cardiovascular: QTc prolongation, QRS widening, orthostatic hypotension, tachycardia. Fatal arrhythmias in overdose. Neurological: Profound morning hangover/sedation, delirium (especially elderly), lowers seizure threshold. Gastrointestinal: Severe dry mouth, severe constipation, urinary retention (Anticholinergic toxidrome). Metabolic: Weight gain (H1 blockade).

Key Interactions

MAOIs, Tramadol (Serotonin Syndrome). Additive anticholinergic burden (Oxybutynin, Promethazine). CYP2D6 inhibitors (Fluoxetine, Paroxetine) spike TCA blood levels into the toxic range.

Monitoring

Baseline ECG (Check QTc and QRS width) before escalating doses. Monitor for urinary retention and severe constipation.

Clinical Pearl

If a patient overdoses on Amitriptyline, their QRS will widen on the ECG. You MUST push IV Sodium Bicarbonate. It overwhelms the sodium channel blockade and saves the heart.

Access

Endep10 mg tablet

Brand: Endep
Formulation: Tablets (10 mg, 25 mg, 50 mg)

Amitriptyline

TCA·Psychiatry - Antidepressants

Major Depressive Disorder

PBSTCAEndep10 mg tabletS4+1

Max Dose

150 mg/day

Half-life

20 h

Toxicity in OD

CRITICAL

Anticholinergic

SEVERE

Rapid Summary

Overview

Maximum Dose

Max 150 mg/day (Depression). Max 50-75 mg/day (Neuropathic pain).

Clinical Focus

Fatal in overdose. TCAs block cardiac sodium channels causing widening QRS, lethal arrhythmias, and profound anticholinergic coma.

Bottom Line

Amitriptyline is a TCA widely used at low dose for neuropathic pain, migraine prophylaxis, and insomnia, but is cardiotoxic in overdose and has significant anticholinergic burden in elderly.

Formulation & Access

Brand Names

Endep

Oral Routes

Tablets (10 mg, 25 mg, 50 mg).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Major Depressive Disorder.

Off-Label

OFF

Neuropathic pain, migraine prophylaxis, IBS-D, severe insomnia.

Clinical Place

First-line low-dose adjunct for chronic nerve pain (e.g., post-herpetic neuralgia, diabetic neuropathy).

Quick reference

Class & Role

TCA — Tricyclic Antidepressant (TCA).

Route / Formulation

Tablets (10 mg, 25 mg, 50 mg). (Endep)

Usual Dose & Max

Start PO 10-25 mg NOCTE. Titrate up every 1-2 weeks. Target 25-75 mg NOCTE. Max 150 mg/day (Depression).

Key Indication Doses

Best Uses

Amitriptyline is a TCA widely used at low dose for neuropathic pain, migraine prophylaxis, and insomnia, but is cardiotoxic in overdose and has significant anticholinergic burden in elderly.

Avoid / Cautions

Recent myocardial infarction, heart block, severe hepatic impairment, concurrent MAOIs. Pregnancy Category C.

Key Risks

Key Interactions

MAOIs, Tramadol (Serotonin Syndrome). Additive anticholinergic burden (Oxybutynin, Promethazine). CYP2D6 inhibitors (Fluoxetine, Paroxetine) spike TCA blood levels into the toxic range.

Monitoring

Baseline ECG (Check QTc and QRS width) before escalating doses. Monitor for urinary retention and severe constipation.

Clinical Pearl

If a patient overdoses on Amitriptyline, their QRS will widen on the ECG. You MUST push IV Sodium Bicarbonate. It overwhelms the sodium channel blockade and saves the heart.

Access

Endep10 mg tablet

Brand: Endep
Formulation: Tablets (10 mg, 25 mg, 50 mg)