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Amitriptyline HydrochloridePronouncation: (am-ee-TRIP-tih-leen HIGH-droe-KLOR-ide)
Class: Tricyclic compound
- Tablets 10 mg
- Tablets 25 mg
- Tablets 50 mg
- Tablets 75 mg
- Tablets 100 mg
- Tablets 150 mg
Mechanism of Action
Inhibits presynaptic reuptake of norepinephrine and serotonin in CNS.
Metabolized in the liver by N-demethylation and bridge hydroxylation. Nortriptyline is an intermediate active metabolite.
50% to 66% excreted in the urine within 24 h. Excreted as glucuronide or sulfate conjugate of metabolites. A small amount of unchanged drug excreted in the urine. T ½ is 31 to 46 h.
May have increased plasma levels. Dosage adjustment may be necessary.
Indications and Usage
Relief of depression. Endogenous depression is more likely to be alleviated than are other depressive states.
Management of chronic pain associated with migraine, tension headache, phantom limb pain, tic douloureux, diabetic neuropathy, peripheral neuropathy, cancer or arthritis; treatment of panic and eating disorders.
Hypersensitivity to any tricyclic antidepressant; use during acute recovery phase of MI; concomitant use with MAOIs, except under close medical supervision; may block the antihypertensive action of guanethidine or similarly active compounds.
Dosage and AdministrationAdults
Titrate dosage over 2 wk to 1 mo. Give maintenance dose 6 mo to 1 yr. Do not interrupt therapy abruptly; reduce over 2 wk period.Outpatients
PO 75 to 150 mg/day in divided doses; give in evening or at bedtime because of sedative effects.Hospitalized patients
PO 100 to 300 mg/day.Adolescents and elderly
PO 10 mg 3 times daily and 20 mg at bedtime.Maintenance
PO 40 to 100 mg/day.
Give drug with or immediately after food or fluid and in late afternoon or at bedtime because of sedative effect. Tablets may be crushed.
Store at room temperature and protect from light.
Drug InteractionsBarbiturates, charcoal
May cause decreased blood levels of amitriptyline.Cimetidine, fluoxetine
May cause increased blood levels of amitriptyline.Clonidine
Use with product may result in hypertensive crisis.CNS depressants
Depressant effects may be additive.MAOIs
May cause hyperpyretic crises, severe convulsions, and death when given with amitriptyline.
Laboratory Test Interactions
None well documented.
Orthostatic hypotension; hypertension; tachycardia; palpitations; arrhythmias; ECG changes.
Confusion; hallucinations; disturbed concentration; decreased memory; delusions; nervousness; restlessness; agitation; panic; insomnia; nightmares; mania; exacerbation of psychosis; drowsiness; dizziness; weakness; emotional lability; numbness; tremors; extrapyramidal symptoms (eg, pseudoparkinsonism, movement disorders, akathisia); seizures.
Rash; pruritus; photosensitivity reaction; dry skin; acne; itching.
Conjunctivitis; blurred vision; increased IOP; mydriasis; tinnitus; nasal congestion; peculiar taste in mouth.
Nausea; vomiting; anorexia; GI distress; diarrhea; flatulence; dry mouth; constipation.
Impotence; sexual dysfunction; menstrual irregularities; dysmenorrhea; nocturia; urinary frequency; UTI; vaginitis; cystitis; urinary retention and hesitancy.
Bone marrow depression, including agranulocytosis; eosinophilia; purpura; thrombocytopenia; leukopenia.
Elevation or depression of blood sugar levels.
Pharyngitis; rhinitis; sinusitis; cough.
Category D .
Excreted in breast milk.
Not recommended for children younger than 12 yr of age.
Special Risk Patients
Caution is needed with history of seizures; urinary retention; urethral or ureteral spasm; angle-closure glaucoma or increased IOP; cardiovascular disorders; hyperthyroidism and patients receiving thyroid medication; hepatic or renal function impairment; schizophrenia; paranoia.
Changing from MAOI to amitriptyline
Waiting period of 7 to 10 days is necessary to prevent hypertensive crisis.
Some TCAs inhibit neuronal reuptake of serotonin and can increase synaptic serotonin levels.
Confusion, agitation, hallucinations, seizures, status epilepticus, clonus, choreoathetosis, hyperactive reflexes, positive Babinski's sign, coma, cardiac arrhythmias, renal failure, flushing, dry mouth, dilated pupils, hyperpyrexia.
- Caution patient not to stop taking medication abruptly without consulting health care provider.
- Warn patient of the risk of seizure.
- Reinforce importance of follow-up visits to health care provider for monitoring drug's effectiveness and side effects.
- Explain that drug effects may not be evident for 4 to 6 wk but that side effects are usually noted early.
- Patient should complete the full course of therapy.
- Tell patient that side effects are reduced if drug is taken at bedtime.
- Advise patient that weight gain often results from increased appetite caused by drug.
- Inform patient that urine may turn blue-green.
- Emphasize the need for regular dental care because oral dryness can increase risk for dental caries.
- Instruct patient to report the following symptoms to health care provider: blurred vision, sore throat, fever, increased heart rate, impaired coordination, difficult urination, excessive sedation, or seizures.
- Instruct patient to take sips of water frequently, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
- Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
- Instruct patient to avoid intake of alcohol beverages or other CNS depressants.
- Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.
- Caution patient to avoid exposure to sunlight, and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.