OVERDO
RECOMMENDED DOSAGE SCHEDULES SHOULD BE STRICTLY FOLLOWED. THIS MEDICATION SHOULD BE KEPT IN A CHILD-RESISTANT CONTAINER AND OUT OF THE REACH OF CHILDREN, SINCE AN OVERDOSAGE MAY RESULT IN SEVERE, EVEN FATAL, RESPIRATORY DEPRESSION.
Diagnosis
Initial signs of overdosage may include dryness of the skin and mucous membranes, mydriasis, restlessness, flushing, hyperthermia, and tachycardia followed by lethargy or coma, hypotonic reflexes, nystagmus, pinpoint pupils, and respiratory depression. Respiratory depression may be evidenced as late as 30 hours after ingestion and may recur in spite of an initial response to narcotic antagonists. TREAT ALL POSSIBLE OVERDOSAGES AS SERIOUS AND MAINTAIN MEDICAL OBSERVATION FOR AT LEAST 48 HOURS, PREFERABLY UNDER CONTINUOUS HOSPITAL CARE.
Treatment
In the event of overdose, induction of vomiting, gastric lavage, establishment of a patent airway, and possibly mechanically assisted respiration are advised. In vitro and animal studies indicate that activated charcoal may significantly decrease the bioavailability of diphenoxylate. In non-comatose patients, a slurry of 100 g of activated charcoal can be administered immediately after the induction of vomiting or gastric lavage.
A pure narcotic antagonist (e.g., naloxone) should be used in the treatment of respiratory depression caused by diphenoxylate hydrochloride and atropine sulfate. When a narcotic antagonist is administered intravenously, the onset of action is generally apparent within 2 minutes. It may also be administered subcutaneously or intramuscularly, providing a slightly less rapid onset of action but a more prolonged effect.
To counteract respiratory depression caused by diphenoxylate/atropine overdosage, the following dosage schedule for the narcotic antagonist naloxone hydrochloride should be followed:
Adult Dosage: The usual initial adult dose of naloxone hydrochloride is 0.4 mg administered intravenously. If respiratory function does not adequately improve after the initial-dose, the same IV dose may be repeated at 2 to 3 minute intervals.
Children: The usual initial dose of naloxone hydrochloride for children is 0.01 mg/kg of body weight administered intravenously and repeated at 2 to 3 minute intervals if necessary.
Following initial improvement of respiratory function, repeated doses of naloxone hydrochloride may be required to counteract recurrent respiratory depression. Supplemental intramuscular doses of naloxone hydrochloride may be utilized to produce a longer-lasting effect.
Since the duration of action of diphenoxylate hydrochloride is longer than that of naloxone hydrochloride, improvement of respiration following administration may be followed by recurrent respiratory depression. Consequently, continued observation is necessary until the effect of diphenoxylate hydrochloride on respiration has passed. This effect may persist for many hours. The period of observation should extend over at least 48 hours, preferably under continuous hospital care. Although signs of overdosage and respiratory depression may not be evident soon after ingestion of diphenoxylate hydrochloride, respiratory depression may occur from 12 to 30 hours later.
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