Amitriptyline Hydrochloride
Indications
Amitriptyline Hydrochloride is used for:
Migraine headache, Depression, Neuropathic pain, Post-herpetic neuralgia, Nocturnal enuresis
Adult Dose
Adult: PO Depression Initial:50-75 mg/day; up to 150 mg/day if needed. Max: 300 mg/day in severe cases.
Neuropathic pain Initial: 10-25 mg/day at night, up to 75 mg/day if needed.
Migraine prophylaxis Initial: 10 mg/day at night. Maintenance: 50-75 mg/day at night.
Elderly: Initially, 25-50 mg/day as a single dose (at bedtime) or in divided doses.
Child Dose
PO Depression
Child: Adolescent: Initially, 25-50 mg/day as a single dose (at bedtime) or in divided doses.
Nocturnal enuresis
Child: 6-10 yr 10-20 mg/day; 11-16 yr 25-50 mg/day. All doses to be given at bedtime. Max duration: 3 mth.
Renal Dose
Administration
May be taken with or without food.
Contra Indications
Hypersensitivity, use of MAO inhibitors within the last 14 days; acute recovery phase post-MI. Concurrent usage with cisapride.
Precautions
Bipolar illness, pregnancy, lactation elderly, CVS disease, renal or liver impairment, epilepsy, thyroid dysfunction, DM. Avoid abrupt withdrawal; urinary retention, prostatic hyperplasia; chronic constipation; angle-closure glaucoma; phaeochromocytoma. Monitor for signs of clinical worsening, suicidality or behavioural changes. May increase risks associated with electro-convulsive therapy. May affect ability to drive or operate machinery.
Lactation: Distributed in breast milk; do not nurse (AAP states effect on nursing infants is unknown but may be of concern)
Pregnancy-Lactation
Pregnancy category: C
Lactation: Distributed in breast milk; do not nurse (AAP states effect on nursing infants is unknown but may be of concern)
Interactions
Increased risk of serotonin syndrome w/ SSRIs, TCAs, triptans, fentanyl, lithium, tramadol. May reduce plasma levels w/ barbiturates, rifampicin and other anticonvulsants. May increase plasma levels w/ methylphenidate, cimetidine, antipsychotics, Ca channel blockers. May precipitate cardiac arrhythmias w/ thyroid hormones. May reduce antihypertensive effects of debrisoquine, guanethidine and clonidine. May increase pressor effect of epinephrine and norepinephrine. May increase the risk of ventricular arrhythmias w/ antiarrhythmics (e.g. amiodarone or quinidine), antihistamines astemizole, terfenadine, some antipsychotics (pimozide, sertindole, and thioridazine), sotalol, cisapride and halofantrine.
Potentially Fatal: Increased risk of serotonin syndrome w/ MAOIs, linezolid and methylene blue.
Adverse Effects
Side effects of Amitriptyline Hydrochloride :
Postural hypotension, tachycardia, conduction disturbances. Dry mouth, wt gain, sour or metallic taste, stomatitis, constipation; blurring of vision, urinary retention, fatigue, dizziness, weakness, tremors, headache, confusion and delirium in elderly, sexual disturbances; peripheral neuropathy; urticaria, angioedema, sweating.
Potentially Fatal: Cardiac arrhythmias.
Mechanism of Action
Amitriptyline is a dibenzocycloheptadiene tricyclic antidepressant. It increases synaptic concentration of serotonin and/or norepinephrine in the CNS by blocking the neuronal reuptake of norepinephrine and serotonin.