OVERDOSAGE
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 despite an
initial response to narcotic antagonists. TREAT ALL POSSIBLE LOMOTIL 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 noncomatose
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 (eg, naloxone) should be used in the treatment of
respiratory depression caused by Lomotil. When a narcotic antagonist is
administered intravenously, the onset of action is generally apparent within two
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 Lomotil overdosage, the
following dosage schedule for the narcotic antagonist naloxone hydrochloride
should be followed:
Adult dosage: An initial dose of 0.4 mg to 2 mg of
naloxone hydrochloride may be administered intravenously. If the desired degree
of counteraction and improvement in respiratory functions is not obtained, it
may be repeated at 2- to 3-minute intervals. If no response is observed after 10
mg of naloxone hydrochloride has been administered, the diagnosis of
narcotic-induced or partial narcotic-induced toxicity should be questioned.
Intramuscular or subcutaneous administration may be necessary if the intravenous
route is not available.
Children: The usual initial dose in children is
0.01 mg/kg body weight given I.V. If this dose does not result in the desired
degree of clinical improvement, a subsequent dose of 0.1 mg/kg body weight may
be administered. If an I.V. route of administration is not available, naloxone
hydrochloride may be administered I.M. or S.C. in divided doses. If necessary,
naloxone hydrochloride can be diluted with sterile water for injection.
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, continuous 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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