Schulman EA, Silberstein SD. Symptomatic and prophylactic treatment of migraine and tension-type headache. Neurology 1992;42(suppl 2):16Ñ21. [amitriptyline dosage, atenolol dosage, chlorpromazine dosage, cyproheptadine dosage, dexamethasone dosage, diflunisal dosage, diltiazem dosage, doxepin dosage, fluoxetine dosage, haloperidol dosage, ibuprofen dosage, indomethacin dosage, ketoprofen dosage, meclofenamate, mefenamic acid dosage, meperidine dosage, morphine dosage, nadolol dosage, naproxen dosage, nifedipine dosage, nimodipine dosage, nortriptyline dosage, phenelzine dosage, phenytoin dosage, piroxicam dosage, prednisone dosage, propranolol dosage, sulindac dosage, timolol dosage, verapamil dosage, £-blockers overview]
DESCRIPTION
Amitriptyline is an oral and parenteral tertiary amine tricyclic antidepressant. It is structurally related to the thioxanthene antipsychotics such as thiothixene. Amitriptyline is also related to the skeletal muscle relaxant cyclobenzaprine, although amitriptyline is not believed to possess muscle-relaxant properties. Amitriptyline is metabolized to nortriptyline, an active metabolite that is also marketed separately. Clinically, amitriptyline is used to treat depression, pain of neuropathic origin, attention-deficit hyperactivity disorder, functional enuresis in children, panic disorder, and phobic disorder, and to manage some eating disorders. Amitriptyline was approved by the FDA in 1961.
CLINICAL PHARMACOLOGY
Mechanism of Action: The precise action of tricyclic antidepressants is not fully understood, but it is believed that the most important effect is the decreased reuptake of norepinephrine and serotonin. Amitriptyline appears to exert effects on both norepinephrine and serotonin (5-HT), although the selective-acting desipramine is a more potent inhibitor of norepinephrine transport. Amitriptyline is metabolized to nortriptyline, which accounts for most of the norepinephrine-reuptake inhibition after amitriptyline administration. Nortriptyline itself also possesses antidepressant activity. Additional hydroxy metabolites apparently are active as well. The down-regulation of limbic beta-receptors that results from this synaptic neurotransmitter increase occurs ~5Ñ7 days after therapeutic concentrations are reached.
Monoamine oxidase is not inhibited by either amitriptyline or nortriptyline. Tricyclic antidepressants do not affect dopamine reuptake. Varying degrees of sedation can be produced, and the seizure threshold can be lowered. Amitriptyline possesses strong anticholinergic activity. Cardiac dysrhythmias can result from the direct quinidine-like effect on cardiac function combined with anticholinergic activity and norepinephrine potentiation. Changes in sex hormone concentrations and blood glucose can result from amitriptyline's effect on the endocrine system.
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