Pharmaniaga Diphenhydramine Expectorant Overdosage

Overdosage of antihistamine may be fatal especially in infants and children.
Symptoms: For antihistamines: In infants and children, CNS stimulation predominates over CNS depression, causing ataxia, excitement, tremors, psychoses, hallucinations and convulsion; hyperpyrexia may also occur. Deepening coma and cardiorespiratory collapse may follow.
In adults, CNS depression is more common with drowsiness, coma and convulsions, progressing to respiratory failure or possibly cardiovascular collapse. Large doses of ammonium chloride may cause a profound acidosis and hypokalaemia.
Treatment: There is no specific antidote for overdosage with antihistamines and Ammonium chloride, treatment is symptomatic and supportive until possible utilisation of the following: induction of emesis (syrup of ipecac is recommended, however, precaution against respiration is necessary especially in infants and children); gastric lavage if patient is unable to vomit within 3 hours of ingestion; saline carthartics are sometimes used; vasopressors to treat hypotension, however, epinephrine should not be used since it may further lower blood pressure; oxygen and intravenous fluids; precaution against use of stimulant because they may cause seizures.