Overdosage with triprolidine may produce reactions varying from depression to stimulation of the Central Nervous System: the later is particularly likely in children. Atropine-like signs and symptoms (dry mouth, fixed dilated pupils, flushing, tachycardia, hallucination, convulsions, urinary retention, cardiac arrthymias and coma) may occur. Overdosage with pseudoephedrine can cause excessive CNS stimulation resulting in excitement, nervousness, anxiety, tremor, restlessness and insomnia. Other effects include tachycardia, hypertension, pallor, mydriasis, hyperglycaemia 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 hypotension can occur probably due to compartmental shift rather than depletion of potassium. Gastric emptying 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 activated charcoal as a slurry is beneficial after lavage and or emesis, if less than four hours have passes since ingestion. Saline cathartics, such as milk of magnesia, help to dilute the concentration of the drugs in the bowels by drawing water into the gut, thereby hastening drug elimination.
Adrenergic receptor blocking agents are antidotes to pseudoephedrine. In practice, the most useful is the beta-blocker propranolol, which is indicated when there are signs of cardiac toxicity. There are no specific antidotes to triprolidine. Histamine should not be given.