AMITRIPTYLINE oral

Prescription under medical supervision

Therapeutic action

– Tricyclic antidepressant

Indications

– Neuropathic pain
– Major depression

Forms and strengths

– 25 mg tablet

Dosage

– Neuropathic pain
Adult: 25 mg once daily at bedtime (Week 1); 50 mg once daily at bedtime (Week 2); 75 mg once daily at bedtime (as of Week 3) 

– Depression
Adult: 25 mg once daily at bedtime. Depending on efficacy and tolerance, increase over 8 to 10 days, up to 75 mg once daily at bedtime.

– Do not exceed 150 mg daily. Reduce the dose by half in elderly patients.

Duration

– Neuropathic pain: 3 to 6 months after pain relief is obtained. If pain reappears, recommence treatment.
– Depression: minimum 9 months. Treatment should be discontinued gradually (over 4 weeks). If signs of relapse or withdrawal occur, increase the dose.

Contra-indications, adverse effects, precautions

– Do not administer to patients with recent myocardial infarction, arrhythmia, closed-angle glaucoma, prostate disorders.
– Administer with caution and carefully monitor use in elderly patients and in patients with epilepsy, chronic constipation, renal or hepatic impairment (reduce the dose by half), history of bipolar disorders and suicidal ideation.
– May cause:
• drowsiness, orthostatic hypotension, sexual dysfunction;
• anticholinergic effects: dry mouth, constipation, blurred vision, tachycardia, disorders of micturition. Treatment should be discontinued in the event of severe reactions (mental confusion, urinary retention, cardiac rhythm disorders);
– Administer with caution and monitor combination with: CNS depressants (opioid analgesics, sedatives, H1 antihistamines, etc.), drugs known to have anticholinergic effects (atropine, chlorpromazine, promethazine, etc.), drugs which lower the seizure threshold (antipsychotics, mefloquine, etc.), serotonergic drugs (SSRI, tricyclic antidepressants, ondansetron, tramadol, etc.), anti-hypertensive drugs.
– Avoid alcohol during treatment.
– Pregnancy: re-evaluate whether the treatment is still necessary; if it is continued, decrease the dose at the end of pregnancy to limit gastrointestinal and neurological adverse effects in the neonate.
– Breast-feeding: monitor the child for excessive somnolence.

Remarks

– Sedative effect occurs following initial doses, analgesic effect is delayed for 7 to 10 days and the antidepressant effect is delayed for at least 4 weeks. This must be explained to the patient.
– For neuropathic pain, amitriptyline is often administered in combination with carbamazepine.
– Storage: below 25 °C -