levothyroxine sodium




Concise Prescribing Info
Levothyroxine Na
Benign euthyroid goiter in patients w/ normal thyroid function. Prophylaxis of relapse after surgery for euthyroid goiter, depending on the post-op hormone status. Substitution therapy in hypothyroidism (to replace natural thyroid hormones, when thyroid gland does not produce enough). Suppression therapy in thyroid cancer (to suppress tumor growth in patients w/ thyroid cancer). 25 mcg, 50 mcg & 100 mcg: Concomitant therapy during anti-thyroid medicinal treatment of hyperthyroidism (to balance thyroid hormone levels when overproduction of thyroid hormones is treated w/ antithyroid medicines). 100 mcg & 150 mcg: Diagnostic use for thyroid suppression testing.
Dosage/Direction for Use
Benign euthyroid goiter 75-200 mcg/day. Prophylaxis of relapse after surgery for euthyroid goiter 75-200 mcg/day. Substitution therapy in hypothyroidism Adult Initial dose: 25-50 mcg/day. Maintenance dose: 100-200 mcg/day. Childn Substitution therapy in hypothyroidism Initial dose: 12.5-50 mcg/day. Maintenance dose: 100-150 mcg/m2 body surface. Suppression therapy in thyroid cancer 150-300 mcg/day. Concomitant supplement action during antithyroid drug treatment of hyperthyroidism 50-100 mcg/day. Diagnostic use for thyroid suppression testing 100 mcg Wk 1 & 2 prior to test: 200 mcg/day. 150 mcg Wk 3 & 4 prior to test: 75 mcg/day. Wk 1 & 2 prior to test: 150 mcg/day.
Should be taken on an empty stomach: Take 30 min before breakfast.
Hypersensitivity. Untreated adrenal & pituitary insufficiency, untreated thyrotoxicosis, acute MI, acute myocarditis/pancarditis. Combination therapy w/ anti-thyroid agent for hyperthyroidism during pregnancy.
Special Precautions
Not to be used for wt reduction. Treat coronary insufficiency, angina pectoris, arteriosclerosis, HTN prior starting therapy or performing thyroid suppression test. Patients at risk of psychotic disorders is recommended to start at low dose & slowly increase at the beginning of the therapy. Thyroid autonomy must be excluded or treated prior therapy. Avoid drug-induced hyperthyroidism in patients w/ coronary insufficiency, heart failure & tachycardiac arrhythmias. Not recommended for hyperthyroid metabolic states. Determine etiology of secondary hypothyroidism before giving thyroid replacement therapy. Close monitoring of thyroid function in postmenopausal women w/ hypothyroidism & risk of osteoporosis is recommended. Adjust Euthyrox dosage following patient's response & laboratory test. Galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption. Coadministration w/ orlistat. Pregnancy & lactation. Elderly.
Adverse Reactions
Irregular or rapid heart rate (tachycardia, palpitations, arrhythmias eg, atrial fibrillation & extrasystoles), chest pain (angina pectoris), headache, muscle weakness or cramps, warmth & redness of the face (flushing), fever, vomiting, disorders of menstruation, pseudotumor cerebri, trembling, restlessness, sleep disturbances, sweating, wt loss & diarrhea.
Drug Interactions
May reduce effect of antidiabetics. May intensify anticoagulant effect of coumarin derivatives. May influence effect of levothyroxine w/ PIs (eg, ritonavir, indinavir, lopinavir). Elevated fT4 & fT3 fraction & increased hepatic metabolization w/ phenytoin. Elevated fT4 fraction w/ salicylates, dicoumarol, furosemide (in high doses of 250 mg) & clofibrate. Hypothyroidism &/or reduced hypothyroidism control w/ orlistat. May decrease absorption w/ sevelamer. May decrease efficacy w/ tyrosine-kinase inhibitors (eg, imatinib, sunitinib). Inhibit absorption w/ ion exchange resins (eg, cholestyramine, colestipol). Potentially decreased effect w/ Al (eg, antacids, sucralfates), Fe containing drugs & Ca salts. Propylthiouracil, glucocorticoids, β-sympatholytics, iodine-containing contrast media & amiodarone inhibit peripheral conversion of T4 to T3. May trigger hyperthyroidism & hypothyroidism w/ amiodarone. Decreased efficacy & increased TSH level w/ sertraline, chloroquine/proguanil. Increased hepatic clearance w/ hepatic enzyme inducers (eg, barbiturates, carbamazepine). Women on estrogen-containing contraceptives or postmenopausal under hormone-replacement therapy may have increased need for levothyroxine. May lower uptake w/ soy products.
MIMS Class
ATC Classification
H03AA01 - levothyroxine sodium ; Belongs to the class of thyroid hormones.
Euthyrox tab 50 mcg
Euthyrox tab 150 mcg
Euthyrox tab 100 mcg
Euthyrox tab 25 mcg
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Sign up for free
Already a member? Sign in