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DRUG INTERACTIONS
Drug Interactions:
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MAOI and
tricyclic antidepressants may prolong and intensify the anticholinergic
(drying) effects of antihistamines.
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Beta-adrenergic
blockers and MAOI may potentiate the pressor effect of pseudoephedrine.
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Concurrent
use of digitalis glycosides may increase the possibility of cardiac
arrhythmias.
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Sympathomimetics
may reduce the hypotensive effects of guanethidine, mecamylamine, methyldopa,
reserpine and veratrum alkaloids.
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Concurrent
use of tricyclic antidepressants may antagonize the effects of pseudoephedrine.
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Concomitant
use of antihistamines with alcohol, tricyclic antidepressants, barbiturates and
other CNS depressants may have an additive effect.
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OVERDOSAGE:
Overdosage with pseudoephedrine may manifest itself as excessive CNS stimulation resulting in excitement, tremor, restlessness and insomnia. Other effects may include tachycardia, hypertension, pallor, mydriasis, hyperglycemia and urinary retention. Severe overdosage may cause tachypnea or hyperpnea, hallucinations, convulsions or delirium, but in some individuals there may be CNS depression with somnolence, stupor or respiratory depression. Arrhythmias (including ventricular fibrillation) may lead to hypotension and circulatory collapse. Severe hypokalemia can occur, probably due to a compartmental shift rather than a depletion of potassium. No organ damage or significant metabolic derangement is associated with pseudoephedrine overdosage. Overdose with dextromethorphan include CNS
effects as most prevalent, such as psychosis, hallucinations, mania, seizures,
ataxia, dizziness, and psychological dependence. Urinary retention and
tachycardia have also been reported. Very high doses may lead to respiratory
depression coma/unconsciousness, and cyanosis.Manifestations of antihistamine overdosage may vary from CNS depression (sedation, apnea, cardiovascular collapse) to stimulation (insomnia, hallucinations, tremors or convulsions). Other signs and symptoms may be dizziness, tinnitus, ataxia, blurred vision, and hypotension. Stimulation is particularly likely in children, as are atropine-like signs and symptoms (dry mouth; fixed, dilated pupils; flushing; hyperthermia and gastrointestinal symptoms).
Treatment:
In the event of overdosage, emergency treatment
should be started immediately. Since the action of long-acting products may
continue for as long as 18 hours, treatment of overdosage should be directed
toward reducing further absorption and supporting the patient for at least that
length of time. Gastric emptying (Syrup of Ipecac) and/or lavage is recommended as soon as possible after ingestion, even if the patient has vomited spontaneously. Either isotonic or half-isotonic saline may be used for lavage. Administration of an activated charcoal slurry is beneficial after lavage and/or emesis if less than four hours have passed since ingestion. Saline cathartics, such as Milk of Magnesia, are useful for hastening the evacuation of unreleased medication. Adrenergic receptor blocking agents are antidotes to pseudoephedrine. In practice, the most useful is the beta-blocker propanolol, which is indicated when there are signs of cardiac toxicity. In severe cases of overdosage, it is essential to monitor both the heart (by electrocardiograph) and plasma electrolytes, and to give intravenous potassium as indicated.
Vasopressors may be used to treat hypotension. Excessive CNS stimulation may be counteracted with parenteral diazepam. Stimulants should not be used. Hyperpyrexia, especially in children, may require treatment with tepid water sponge baths or a hyperthermic blanket. Apnea is treated with ventilatory support.
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CONTRAINDICATIONS
Atuss® DS Tannate Suspension is contraindicated in patients with hypersensitivity to chlorpheniramine, dextromethorphan, or with hypersensitivity or idiosyncrasy to sympathomimetic amines which may be manifested by insomnia, dizziness, weakness, tremor or arrhythmias. Sympathomimetic amines are contraindicated in patients with severe hypertension, severe coronary artery disease, and patients that are now taking a prescription monoamine oxidase inhibitor (MAOI) (certain drugs for depression, psychiatric, or emotional conditions, or Parkinson’s disease), or for two weeks after stopping the MAOI drug. This product is contraindicated in woman who are pregnant or nursing.
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DRUG ABUSE AND DEPENDENCE:
Pseudoephedrine, like other CNS stimulants, has been abused. At high doses, subjects commonly experience an elevation of mood, a sense of increased energy and alertness, and decreased appetite. Some individuals become anxious, irritable, and loquacious. In addition to the marked euphoria, the user experiences a sense of markedly enhanced physical strength and mental capacity. With continued use, tolerance develops, the user increases the dose and toxic signs and symptoms appear. Depression may follow rapid withdrawal. Narcotic antitussives and stimulants, such as pseudoephedrine, are banned and tested for by the U.S. Olympic Committee (USOC) and the National Collegiate Athletic Association (NCAA).
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