levothyroxine sodium




Luen Cheong Hong (M)
Luen Cheong Hong
Concise Prescribing Info
Levothyroxine Na
Management of demonstrated thyroid hormone deficiency; management of TSH-responsive tumours of the thyroid.
Dosage/Direction for Use
Adult Initial dose: 50-100 mcg daily, increase by 25-50 mcg according to response at not <4-wkly intervals, up to 100-200 mcg/day. Maintenance: 100-200 mcg/day. Childn (w/ congenital & acquired hypothyroidism) ≥12 yr approx 2 mcg/kg/day; 6-12 yr approx 4 mcg/kg/day; 1-5 yr approx 5 mcg/kg/day; 6-12 mth approx 6 mcg/kg/day; 0-6 mth approx 8 mcg/kg/day. Elderly ≥60 yr & w/ ischaemic heart disease Initial dose: 25 or 50 mcg/day.
Should be taken on an empty stomach: Take 30 min-1 hr before meals or other medications. Best taken in the morning.
Hypersensitivity. Untreated hyperthyroidism; thyrotoxicosis; uncorrected primary or secondary adrenal insufficiency; acute MI uncomplicated by hypothyroidism; acute myocarditis; acute pancarditis.
Special Precautions
CV disorder; DM or diabetes insipidus. Corticosteroid replacement therapy must precede initiation of Eltroxin therapy. Associated w/ increased bone resorption, thereby decreasing bone mineral density. Renal & liver disorders may influence thyroid function tests. History of hyperthyroidism; thyrotoxicosis; long-standing hypothyroidism & myxoedema. Malabsorption syndromes. Enhanced risk of breast cancer. Childn. Elderly or patients w/ long-standing hypothyroidism, & w/ ischaemic heart disease.
Adverse Reactions
Chest pain, increased BP, tachycardia, cardiac arrhythmias, palpitations, angina, myocardial ischaemia, MI, heart failure, death; irritability, anxiety, nervousness, excitability, restlessness, tremors, headache, poor conc, emotional lability, sleep disturbance, insomnia, mania, psychosis, psychotic depression, seizures, petit mal status epilepticus, pseudotumour cerebri (especially in childn); abdominal cramps, nausea, diarrhoea, vomiting, malabsorption; hypersensitivity reactions (eg, skin rash, pruritus, anaphylactic reactions); warmth, erythema, telangectiasia, hyperhidrosis, alopecia, hyperpigmentation; increased minute ventilation, tachypnoea, shortness of breath; myopathy, lid lag, muscle weakness, cramps, premature closure of epiphyses (in childn); amenorrhoea, menstrual irregularities, decreased libido, gynaecomastia (in male), impaired fertility; dyspnoea; fever, glucose intolerance, wt loss, premature craniosynostosis (in childn), TRH suppression, heat intolerance, sweating, flushing, fatigue, increased appetite; hyperthyroidism; decreased bone mineral density.
Drug Interactions
Increased effects of oral anticoagulants, coumarin or indandione derivatives eg, warfarin; phenobarb, dihydrotachysterol. Decreased effect w/ SSRIs eg, sertraline; ion-exchange resins eg, cholestyramine, Na polystyrene sulphonate or colestipol; soya flour, sucralfate, Ca-, Al-, Mg-, Fe supplements, lanthanum, sevelamer, proton pump inhibitors. Increased dosage requirement of insulin & other oral antidiabetic drugs. Decreased peripheral conversion of thyroxine to triiodothyronine w/ β-adrenergic blocking agents eg, propranolol; propranolol, amiodarone, lithium, iodide, oral contrast agents, propylthiouracil, glucocorticoids. Increased clearance of corticosteroids in hyperthyroid patients; decreased in hypothyroid patients. Increased serum thyroxine-binding globulin w/ oestrogen in patients w/ non-functioning thyroid. Increased hepatic degradation w/ antiepileptics eg, phenytoin, carbamazepine, barbiturates; antibacterial eg, rifampicin. Interaction w/ ritonavir, resulting in increased Eltroxin requirements. Decreased absorption w/ oral ciprofloxacin. Decreased conc of serum thyroxine-binding globulin w/ androgens. Marked HTN & tachycardia w/ ketamine. Clinical hypothyroidism w/ lithium. Increased sensitivity to catecholamines w/ TCAs. Risk of coronary insufficiency w/ sympathomimetics. Reduced clinical effect of digoxin. Modified thyroid function tests w/ some NSAIDs, salicylates, diazepam, heparin & fenclofenac.
MIMS Class
Thyroid Hormones
ATC Classification
H03AA01 - levothyroxine sodium ; Belongs to the class of thyroid hormones.
Eltroxin tab 100 mcg
Eltroxin tab 50 mcg
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