Monograph Details
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Endocrine System
> Thyroid disease
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SYNTHROID INJECTION |
| Manufacturer |
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Abbott Laboratories |
| Legal Classification |
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Rx
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| Pharmacological Class |
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T4 (synthetic). |
| Generic Name |
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Levothyroxine sodium 200micrograms, 500micrograms; pwd for IV or IM inj after reconstitution. |
| Also |
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• SYNTHROID
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| Indications |
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Rapid induction in hypothyroidism or myxedema coma, if oral route not feasible. |
| Children |
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Consult manufacturer. |
| Adults |
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Myxedema coma: 200–500micrograms IV once (may reduce dose in cardiovascular disease), may give 100–300micrograms (or more) IV on second day if needed, then 50–100micrograms IV daily; switch to oral form and dose as soon as feasible. Hypothyroidism: ½ oral dose by IV or IM inj; titrate. |
| Contraindications |
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Uncorrected adrenal insufficiency. Untreated thyrotoxicosis. Acute MI. |
| Precautions |
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Not for treatment of obesity or infertility. Cardiovascular disease. Seizures. Adrenocortical insufficiency. Increased sensitivity in severe hypothyroidism. Autonomous thyroid tissue. Elderly. Pregnancy (Cat. A); do not discontinue due to pregnancy. Nursing mothers. |
| Interactions |
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See literature. Absorption reduced by some foods (e.g., soy, fiber), aluminum and magnesium hydroxide, simethicone, calcium carbonate, sodium polystyrene sulfonate, bile acid sequestrants, iron, sucralfate (give at least 4 hrs apart). Potentiates, and is potentiated by, tri- and tetracyclic antidepressants, sympathomimetics. Antagonized by hepatic enzyme inducers (e.g., carbamazepine, phenytoin, phenobarbital, rifampin), sertraline. Antagonizes digoxin. Marked hypertension and tachycardia with ketamine. Estrogens affect thyroid function tests. Monitor oral anticoagulants, antidiabetic agents, theophylline. |
| Adverse Reactions |
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Hyperthyroidism, decreased bone mineral density, transient alopecia; seizures (rare); pseudotumor cerebri in children. |
| How Supplied |
Tabs—100, 1000
Single dose vials (10mL)—1 |
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