Amitriptyline Tablets

Mechanism

Amitriptyline hydrochloride is an antidepressant . It is having a sedative effects. Its mechanism of action in man is not fully elucidated Amitriptyline inhibits the membrane pump mechanism responsible for re- uptake of norepinephrine and serotonin in adrenergic and serotonergic neurons , thereby increases concentration at the synaptic clefts of the brain . The monoamine hypothesis in depression, one of the oldest hypotheses, postulates that deficiencies of serotonin (5-HT) or norepinephrine (NE) neurotransmission in the brain lead to depressive effects.

Amitriptyline inhibits neuronal reuptake of serotonin and noradrenaline from the synapse in the central nervous system, this increases their availability in the synapse to cause neurotransmission on the post synaptic neurone.

Pharmacokinetics

• Absorption: Well absorbed orally; undergoes first-pass metabolism.
• Distribution: Highly protein bound; widely distributed in tissues including CNS.
• Metabolism: Hepatic via CYP450 enzymes to active metabolite nortriptyline.
• Elimination: Excreted via urine; half-life ~10–28 hours.

Side Effects

• Drowsiness
• Dry mouth
• Constipation

Contraindication

• Recent myocardial infarction
• Hypersensitivity to TCAs
• Severe liver disease
• Use with MAO inhibitors
• Cardiac arrhythmias

Interaction

• MAO inhibitors (serotonin syndrome risk)
• Alcohol (enhanced sedation)
• SSRIs (toxicity risk)
• Anticholinergic drugs (increased side effects)

Warning and Precautions

• May be taken with or after meals to reduce gastric irritation. Preferably administered at bedtime due to sedative effect.
• Monitor blood glucose regularly.
• Avoid alcohol.
• Use cautiously in liver disorders.

Dosage

As directed by the Dietician.