OVERDOSE
Signs and Symptoms
Headache, irritability, nervousness, sweating, arrhythmia,
(including tachycardia), increased bowel motility and
menstrual irregularities. Angina pectoris or congestive
heart failure may be induced or aggravated. Shock may
also develop. Massive overdosage may result in symptoms
resembling thyroid storm. Chronic excessive dosage will
produce the signs and symptoms of hyperthyroidism.
Treatment of
OVERDOSE
Dosage should be reduced or therapy temporarily discontinued
if signs and symptoms of overdosage appear. Treatment
may be reinstituted at a lower dosage. In normal individuals,
normal hypothalamic-pituitary-thyroid axis function is
restored in 6 to 8 weeks after thyroid suppression.
Treatment of acute massive thyroid hormone overdosage is
aimed at reducing gastrointestinal absorption of the drugs
and counteracting central and peripheral effects, mainly
those of increased sympathetic activity. Vomiting may be
induced initially if further gastrointestinal absorption
can reasonably be prevented and barring contraindications
such as coma, convulsions, or loss of the gagging reflex.
Treatment is symptomatic and supportive. Oxygen may be administered
and ventilation maintained. Cardiac glycosides may be indicated
if congestive heart failure develops. Measures to control
fever, hypoglycemia, or fluid loss should be instituted
if needed. Antiadrenergic agents, particularly propranolol,
have been used advantageously in the treatment of increased
sympathetic activity. Propranolol may be administered intravenously
at a dosage of 1 to 3 mg over a 10-minute period or orally,
80 to 160 mg/day, especially when no contraindications exist
for its use.
CONTRAINDICATIONS
Thyroid hormone preparations are generally contraindicated
in patients with diagnosed but as yet uncorrected adrenal
cortical insufficiency, untreated thyrotoxicosis and apparent
hypersensitivity to any of their active or extraneous
constituents. There is no well-documented evidence from
the literature however, of true allergic or idiosyncratic
reactions to thyroid hormone.
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