Drug Interactions between amantadine and DuoDote

MONITOR: The anticholinergic-like adverse effects of amantadine may be potentiated by agents with anticholinergic properties such as antihistamines, antispasmodics, class IA antiarrhythmics, neuroleptics, phenothiazines, skeletal muscle relaxants, and tricyclic antidepressants. The cumulative parasympatholytic effects of these agents may produce paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention, and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy, and seizures.

MANAGEMENT: Caution is advised when amantadine is used in combination with anticholinergic agents, particularly in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A reduction in anticholinergic and/or amantadine dosage may be necessary if excessive adverse effects develop.

Pralidoxime and other drugs within the family of compounds called oximes, such as obidoxime, may potentiate the pharmacologic effects of atropine. Signs of atropinization such as flushing, mydriasis, tachycardia, and dry mouth and nose may occur earlier than expected during coadministration with pralidoxime relative to administration of atropine alone, particularly if the total dose of atropine has been large and the administration of pralidoxime was delayed. Clinicians should be aware of the potential interaction and monitor patients as appropriate. Pralidoxime may be used in conjunction with atropine in the treatment of organophosphate insecticide poisoning and nerve agent poisoning in terrorism or chemical warfare.