<p><strong>Signs and symptoms</strong>&nbsp;of overdosage range from mild depression of the&nbsp;central nervous system&nbsp;and&nbsp;cardiovascular system&nbsp;to profound&nbsp;hypotension, respiratory depression, and unconsciousness.<br />
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Stimulation may be evident, especially in pediatric patients and geriatric patients. Convulsions may rarely occur. A paradoxical reaction has been reported in pediatric patients receiving single doses of 75 mg to 125 mg orally, characterized by hyperexcitability and nightmares.<br />
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Atropine-like and symptoms: dry mouth, fixed, dilated pupils, flushing, etc., as well as&nbsp;gastrointestinal&nbsp;symptoms, may occur.<br />
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<strong>Treatment</strong>: Treatment of overdosage is essentially&nbsp;symptomatic&nbsp;and supportive. Only in cases of extreme overdosage or individual sensitivity do vital signs, including respiration, pulse, blood pressure, temperature, and EKG, need to be monitored. Attention should be given to the reestablishment of adequate respiratory exchange through provision of a patent airway and institution of assisted or controlled ventilation. Diazepam may be used to control convulsions.&nbsp;Acidosis&nbsp;and&nbsp;electrolyte&nbsp;losses should be corrected. Note that any depressant effects of promethazine hydrochloride (promethazine hydrochloride injection) are not reversed by&nbsp;naloxone.<br />
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Avoid analeptics, which may cause convulsions. The treatment of choice for resulting hypotension is administration of intravenous fluids, accompanied by repositioning if indicated. In the event that vasopressors are considered for the management of severe hypotension which does not respond to intravenous fluids and repositioning, the administration of levarterenol or phenylephrine should be considered.&nbsp;EPINEPHRINE&nbsp;SHOULD NOT BE USED, since its use in a patient with partial adrenergic blockade may further lower the blood pressure. Extrapyramidal reactions may be treated with&nbsp;anticholinergic&nbsp;antiparkinson agents, diphenhydramine, or barbiturates. Oxygen may also be administered. Limited experience with&nbsp;dialysis&nbsp;indicates that it is not helpful.</p>