Amitriptyline

Q: What are the absolute contraindications to the use of amitriptyline?

Absolute contraindications to amitriptyline include: Recent myocardial infarction / severe heart disease (arrhythmias, heart block).Angle-closure glaucoma.Benign prostatic hyperplasia (BPH).Chronic constipation / paralytic ileus.Concurrent use with MAO inhibitors.

*Amitriptylinum*

For medical students2 min readUpdated 2026-10-10

Amitriptyline (Amitriptylinum) is a tricyclic antidepressant (TCA) that combines potent thymoleptic (mood-elevating) activity with pronounced sedative effects. The drug is widely used in psychiatric and somatic practice to treat major depressive disorders and chronic pain syndromes.

Drug ClassTricyclic antidepressant with strong sedation

MechanismInhibition of neurotransmitter reuptake

Onset of Action2–3 weeks of regular administration

Side EffectsAnticholinergic effects and hypotension

Pharmacological Profile and Mechanism of Action

Amitriptyline is considered one of the most potent agents in its class. Its therapeutic action is based on a combination of strong antidepressant properties and pronounced sedative effects. Additionally, amitriptyline exhibits significant anticholinergic (antimuscarinic) and antihistaminic activity.

The primary mechanism involves the inhibition of the neuronal reuptake of norepinephrine and serotonin. Furthermore, the drug blocks presynaptic autoreceptors and muscarinic receptors on adrenergic nerve terminals. This enhances the release of norepinephrine, which theoretically potentiates the overall antidepressant response. The clinically significant thymoleptic effect does not appear immediately, but manifests after 2–3 weeks of regular use.

Spectrum of Action and Indications

The pharmacological activity profile of amitriptyline includes several key components:

Reduction of anxiety and psychomotor agitation.
Thymoleptic (antidepressant) action.
Marked analgesic activity.

In medical practice, the drug is prescribed across two main profiles:

Psychiatric: endogenous depressions, anxiety-depressive disorders, and neurotic states.
Somatic: chronic pain syndromes (such as neuropathic pain, migraine prophylaxis), managed via its independent analgesic properties.

Pharmacokinetics

The pharmacokinetic properties of amitriptyline ensure its systemic distribution and efficacy:

Absorption: characterized by high absorption following oral administration.
Distribution: exhibits a high degree of plasma and tissue protein binding (exceeding 90%).
Metabolism: hepatic biotransformation (primarily via CYP2C19 and CYP2D6 into active metabolite nortriptyline).
Excretion: eliminated predominantly by the kidneys as metabolites.
Half-life ($T_{1/2}$): ranges from 10 to 26 hours.

Safety Profile and Adverse Effects

Most adverse reactions are related to the non-selective nature of the drug and its unintended interaction with multiple receptor systems:

Anticholinergic (Atropine-like) Effects (blockade of peripheral muscarinic receptors): xerostomia (dry mouth), mydriasis, cycloplegia (blurred vision), and urinary retention.
Cardiovascular Effects: blockade of $\alpha_1$-adrenergic receptors leads to orthostatic hypotension, while membrane-stabilizing (quinidine-like) effects can cause dangerous cardiac arrhythmias and QT prolongation.
CNS and Others: somnolence, dizziness, weight gain, and allergic reactions.

Frequently asked questions

What are the absolute contraindications to the use of amitriptyline?

Absolute contraindications to amitriptyline include:

Recent myocardial infarction / severe heart disease (arrhythmias, heart block).
Angle-closure glaucoma.
Benign prostatic hyperplasia (BPH).
Chronic constipation / paralytic ileus.
Concurrent use with MAO inhibitors.

What symptoms characterize acute amitriptyline overdose?

Acute amitriptyline overdose is characterized by severe anticholinergic toxicity and quinidine-like cardiotoxicity. Coma is often preceded by CNS excitation, delirium, and sometimes seizures.

The clinical presentation in severe toxicity includes:

Cardiac abnormalities — sinus tachycardia, atrial fibrillation, prolonged QRS interval, and dangerous ventricular arrhythmias (e.g., ventricular tachycardia/fibrillation).
Psychiatric disturbances — hallucinations and profound anticholinergic delirium.
Autonomic dysfunction — bowel and bladder atony, severe dry skin, and hyperthermia.

What is the primary mechanism underlying the antidepressant action of amitriptyline?

The drug inhibits the reuptake of neurotransmitters such as norepinephrine and serotonin in the synaptic cleft. Additionally, it blocks presynaptic receptors on adrenergic terminals, enhancing norepinephrine release.

When does the clinically significant therapeutic effect develop?

The clinically significant antidepressant effect does not occur immediately, but typically develops after 2–3 weeks of systematic administration.

What causes the primary adverse effects of amitriptyline?

Adverse reactions are primarily driven by the drug's lack of selectivity, notably the blockade of peripheral muscarinic receptors (causing dry mouth and urinary retention) and $\alpha_1$-adrenergic receptors (causing orthostatic hypotension).

Go deeper

Significance of presynaptic receptor blockade in TCA pharmacology
Mechanisms of TCA-induced analgesia in chronic neuropathic pain
Pathophysiology of orthostatic hypotension due to alpha-1 adrenergic blockade
Pharmacodynamic rationale for the delayed onset of antidepressant action
Comparison between psychiatric and somatic clinical profiles of TCAs