Amitriptyline HCl may block the antihypertensive action of guanethidine or similarly acting compounds.
It should be used with caution in patients with a history of seizures and, because of its atropine-like action, in patients with a history of urinary retention, angle-closure glaucoma or increased intraocular pressure. In patients with angle-closure glaucoma, even average doses may precipitate an attack.
Patients with cardiovascular disorders should be watched closely. Tricyclic antidepressant drugs, including ELAVIL (amitriptyline HCl), particularly when given in high doses, have been reported to produce arrhythmias, sinus tachycardia, and prolongation of the conduction time. Myocardial infarction and stroke have been reported with drugs of this class.
Close supervision is required when amitriptyline HCl is given to hyperthyroid patients or those receiving thyroid medication.
ELAVIL may enhance the response to alcohol and the effects of barbiturates and other CNS depressants. In patients who may use alcohol excessively, it should be borne in mind that the potentiation may increase the danger inherent in any suicide attempt or overdosage. Delirium has been reported with concurrent administration of amitriptyline and disulfiram.
Usage in Pregnancy: Pregnancy Category C:
Teratogenic effects were not observed in mice, rats, or rabbits when amitriptyline was given orally at doses of 2 to 40 mg/kg/day (up to 13 times the maximum recommended human dose**). Studies in literature have shown amitriptyline to be teratogenic in mice and hamsters when given by various routes of administration at doses of 28 to 100 mg/kg/day (9 to 33 times the maximum recommended
human dose), producing multiple malformations. Another study in the rat reported that an oral dose of 25 mg/kg/day (8 times the maximum recommended human dose) produced delays in ossification of fetal vertebral bodies without other signs of embryotoxicity. In rabbits, an oral dose of 60 mg/kg/day (20 times the maximum recommended human dose) was reported to cause incomplete ossification of the cranial bones.
Amitriptyline has been shown to cross the placenta. Although a causal relationship has not been established, there have been a few reports of adverse events, including CNS effects, limb deformities, or developmental delay, in infants whose mothers had taken amitriptyline during pregnancy.
There are no adequate and well-controlled studies in pregnant women. Amitriptyline HCl should be used during pregnancy only if the potential benefit to the mother justifies the potential risk to the fetus.
Amitriptyline is excreted into breast milk. In one report in which a patient received amitriptyline 100 mg/day while nursing her infant, levels of 83 - 141 ng/ml were detected in the mother's serum. Levels of 135 - 151 ng/ml were found in the breast milk, but no trace of the drug could be detected in the infant's serum.
Because of the potential for serious adverse reactions in nursing infants from amitriptyline, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Use in Pediatric Patients:
In view of the lack of experience with the use of this drug in children, it is not recommended at the present time for patients under 12 years of age.
Schizophrenic patients may develop increased symptoms of psychosis; patients with paranoid symptomatology may have an exaggeration of such symptoms. Depressed patients, particularly those with known manic-depressive illness, may experience a shift to mania or hypomania. In these circumstances the dose of amitriptyline may be reduced or a major tranquilizer such as perphenazine may be administered concurrently.
The possibility of suicide in depressed patients remains until significant remission occurs. Potentially suicidal patients should not have access to large quantities of this drug. Prescriptions should be written for the smallest amount feasible.
Concurrent administration of ELAVIL (amitriptyline HCl) and electroshock therapy may increase the hazards associated with such therapy. Such treatment should be limited to patients for whom it is essential.
When possible, the drug should be discontinued several days before elective surgery.
Both elevation and lowering of blood sugar levels have been reported.
ELAVIL (Amitriptyline HCl) should be used with caution in patients with impaired liver function.
Information for Patients
While on therapy with amitriptyline HCl, patients should be advised as to the possible impairment of mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle.
Clinical experience has not identified differences in responses between elderly and younger patients. In general, dose election for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic function, concomitant disease and other drug therapy in elderly patients.
Geriatric patients are particularly sensitive to the anticholinergic side effects of tricyclic antidepressants including amitriptyline HCl. Peripheral anticholinergic effects include tachycardia, urinary retention, constipation, dry mouth, blurred vision, and exacerbation of narrow-angle glaucoma. Central nervous system anticholinergic effects include cognitive impairment, psychomotor slowing, confusion, sedation, and delirium. Elderly patients taking amitriptyline HCl may be at increased risk for falls. Elderly patients should be started on low doses of amitriptyline HCl and observed closely (see DOSAGE AND ADMINISTRATION).