Signs and Symptoms

Dextromethorphan in toxic doses will cause drowsiness, ataxia, nystagmus, opisthotonos and convulsive seizures. Overdosage of phenylpropanolamine may be associated with tachycardia, hypertension and cardiac arrhythmias. The central nervous effect from overdosage of brompheniramine may vary from depression to stimulation, especially in pediatric patients. Anticholinergic effects may also occur.

TOXIC DOSES - Data suggests that individuals may respond in an unexpected manner to apparently small amounts of a particular drug. A 2 1/2 year old child survived the ingestion of 21 mg/kg of dextromethorphan exhibiting only ataxia, drowsiness and fever, but seizures have been reported in two pediatric patients following the ingestion of 13-17 mg/kg. The lethal dosage of phenylpropanolamine is in the range of 50 mg/kg. Another 2 1/2 year old survived a dose of 300-900 mg of brompheniramine.

Treatment

Induce emesis if patient is alert and is seen prior to 6 hours following ingestion. Precautions against aspiration must be taken, especially in infants and pediatric patients. Gastric lavage may be carried out, although in some instances tracheostomy may be necessary prior to lavage. Naloxone hydrochloride 0.005 mg/kg intravenously may be of value in reversing the CNS depression that may occur from an overdosage of dextromethorphan, CNS stimulants may counter CNS depression. Should CNS hyperactivity or convulsive seizures occur, intravenous short-acting barbiturates may be indicated. Hypertensive responses and/or tachycardia should be treated appropriately. Oxygen, intravenous fluids and other supportive measures should be employed as indicated.

Hypersensitivity to any of the ingredients. Do not use in the newborn, in premature infants, in nursing mothers, in patients with severe hypertension or severe coronary artery disease, or in those receiving MAO inhibitors. Antihistamines should not be used to treat lower respiratory tract conditions such as asthma.

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