levothyroxine sodium




Concise Prescribing Info
Levothyroxine Na
Dosage/Direction for Use
Adult Initially 50-100 mcg daily, adjusted at 4-6 wk intervals by 50 mcg until normal metabolism is maintained. May require doses of 100-200 mcg daily. Patient >50 yr Max: 50 mcg/day initially. Patient w/ cardiac disease 50 mcg on alternate days. May be increased by 50 mcg on alternate days at intervals of 4 wk. Congenital hypothyroidism Infant Starting dose: 50 mcg on alternate days w/ increments of 50 mcg on alternated days at intervals of every 2-4 wk. Juvenile myxedema Childn >1 yr 2.5-5 mcg/kg/day.
Should be taken on an empty stomach: Take 30 min-1 hr before meals.
Hypersensitivity. Thyrotoxicosis. Acute MI, myocarditis & pancarditis.
Special Precautions
Patients with panhypopituitarism or other causes predisposing to adrenal insufficiency may cause reactions including dizziness, weakness, malaise, wt loss, hypotension & adrenal crisis. Initiate corticosteroid therapy prior to levothyroxine Na. May cause or aggravate symptoms of angina, arrhythmias, MI, cardiac failure or sudden raise in BP in patients w/ cardiac symptoms, DM or diabetes insipidus. Not for the treatment of obesity or wt loss. Patients w/ myxoedema. Decreased thyroxine absorption in patients w/ malabsorption syndromes. Pregnancy & lactation. Elderly.
Adverse Reactions
Skin rash & pruritus; increased appetite, abnormal wt loss; hyperthyroidism; abdominal cramps, nausea, vomiting, diarrhea; headache, tremors, seizure; anginal pain, cardiac arrhythmias, palpitations, tachycardia, increased BP, heart failure, MI; dyspnea; sweating, alopecia; flushing; skeletal muscle cramps, muscular weakness, premature closure of epiphyses (in childn w/ compromised adult wt); craniosynostosis (in infants); anxiety, emotional lability, nervousness, excitability, insomnia, restlessness; menstrual irregularity, impaired fertility; fatigue, heat intolerance, fever.
Drug Interactions
Increase effects of anticoagulant. May increase phenytoin levels. Enhanced metabolism w/ carbamazepine & phenytoin. Increase metabolism & excretion w/ rifampicin & barbiturates. Cardiac glycosides. Enhanced effects of sympathomimetic agents. Accelerated TCA response. Decreased absorption w/ cholestyramine; Ca- , Al-, Mg-, Fe supplements, Al hydroxide, polystyrene sulfonates, sucralfate, lanthanum, bile acid sequestrants (eg, colestipol), anion/cation exchange resins (eg, kayexalate, sevelamer), Ca carbonate & ferrous sulphate; proton pump inhibitors. Decreased intestinal absorption w/ soy-containing compd & high fibre diets. OCs; other drugs, including estrogen, tamoxifene, clofibrate, methadone & 5-flurouracil; HMG-CoA reductase inhibitors (statins); drugs that may decrease serum conc of thyroxine-binding globulin, including androgens & anabolic steroids; tyrosine kinase inhibitors (eg, imatinib & sunitinib); propranolol, amiodarone, lithium, iodide, oral contrast agents, propylthiouracil, glucocorticoids, sertraline; insulin or oral antidiabetics, phenylbutazone or acetylsalicylic acid
MIMS Class
Thyroid Hormones
ATC Classification
H03AA01 - levothyroxine sodium ; Belongs to the class of thyroid hormones.
Eltroxin tab 100 mcg
100's (P1,077.9/bottle)
Eltroxin tab 50 mcg
100's (P596.81/bottle)
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