Amitriptyline strengthens the depressing effect on the central nervous system following drugs: neuroleptics, sedatives and hypnotics, anticonvulsant drugs, analgesics, funds for anesthesia, alcohol; shows synergism when interacting with other antidepressants. With the combined use of amitriptyline with neuroleptics, and / or anticholinergic drugs, a febrile temperature reaction may occur, paralytic intestinal obstruction. Amitriptyline potentiates the hypertensive effects of catecholamines and other adrenostimulants, which increases the risk of heart rhythm disturbances, tachycardia, severe arterial hypertension, but inhibits the effects of drugs that affect norepinephrine release. Amitriptyline may reduce the antihypertensive effect of guanethidine and drugs with a similar mechanism of action, as well as weaken the effect of anticonvulsants. With the simultaneous use of amitriptyline and anticoagulants - derivatives of coumarin or indanedione, an increase in the anticoagulant activity of the latter is possible. With the simultaneous administration of amitriptyline and cimetidine, plasma concentrations of amitriptyline may increase with the possible development of toxic effects. Inducers of microsomal liver enzymes (barbiturates, carbamazepine) reduces plasma concentrations of amitriptyline. Amitriptyline increases the effect of antiparkinsonian drugs, and other drugs that cause extrapyramidal reactions. Quinidine slows the metabolism of amitriptyline. The combined use of amitriptyline with disulfiram and other acetaldehyde dehydrogenase inhibitors can trigger delirium. Estrogen-containing oral contraceptives can increase the bioavailability of amitriptyline; pimozide and probucol may increase cardiac arrhythmias. Amitriptyline may increase depression caused by glucocorticosteroids; joint use with drugs to treat thyrotoxicosis increases the risk of agranulocytosis. Simultaneous reception of amitriptyline with MAO inhibitors can lead to death. A break in treatment between taking MAO inhibitors and tricyclic antidepressants should be at least 14 days!