Levothyroxine sodium

Levothyroxine sodium: Should be taken on an empty stomach. Take 30 min - 1 hr before meals.

Thyrotoxicosis; uncorrected adrenal insufficiency; acute MI, acute myocarditis, acute pancarditis. Contraindications may vary among individual products (refer to specific product labelling for detailed information).

Patient with adrenal insufficiency; CV disease (e.g. coronary artery disease, angina, hypertension); diabetes mellitus, diabetes insipidus; epilepsy. Not indicated for weight loss or treatment of obesity; suppression of benign thyroid nodules in iodine-sufficient patients; hypothyroidism treatment during recovery phase of subacute thyroiditis. IV inj is not recommended as a substitute for oral preparation. Switching between different brands or preparations is not advisable; if the brand or preparation is changed, closely monitor the patient's laboratory parameters (e.g. serum TSH levels). Neonates, children, and elderly. Pregnancy and lactation. Monitoring Parameters Obtain thyroid function tests (e.g. serum TSH, T₄, free T₄, or T₃ levels) periodically during treatment and dose changes. Perform routine clinical examinations at regular intervals in children to assess mental and physical growth, development, and bone maturation. Monitor heart rate, blood pressure, renal function; BMD (particularly with chronic use in postmenopausal women). Perform ECG before initiating treatment especially in patients with known or at-risk of CV disease. Closely assess for new or worsening CV symptoms (in patients with CV disease and the elderly) and signs and symptoms of hypo- or hyperthyroidism.

Significant: Increased heart rate, cardiac wall thickness or contractility, and precipitated angina (during overtreatment, specifically in elderly and patients with CV disease); worsened glycaemic control (in patients with diabetes mellitus); partial hair loss (during the 1st months of treatment, usually transient); increased bone resorption and reduced BMD (during overreplacement, particularly in postmenopausal women). Rarely, seizures. Cardiac disorders: Palpitations. Endocrine disorders: Thyrotoxic crisis. Gastrointestinal disorders: Diarrhoea, vomiting, abdominal cramps. General disorders and administration site conditions: Malaise, pyrexia, heat intolerance, oedema. Immune system disorders: Hypersensitivity reaction. Investigations: Weight loss. Metabolism and nutrition disorders: Increased appetite. Musculoskeletal and connective tissue disorders: Arthralgia, muscle weakness and spasms. Nervous system disorders: Headache, tremors. Psychiatric disorders: Insomnia, restlessness, nervousness, anxiety, irritability. Reproductive system and breast disorders: Irregular menstruation. Respiratory, thoracic and mediastinal disorders: Dyspnoea. Skin and subcutaneous tissue disorders: Rash, pruritus, hyperhidrosis. Vascular disorders: Flushing.
Potentially Fatal: IV (overtreatment, particularly in elderly and patients with CV disease): Severe CV effects (e.g. myocardial ischaemia, MI, or worsening of CHF).

Enhanced or increased metabolism with carbamazepine, phenytoin, phenobarbital, primidone, and rifampicin. May reduce absorption with antacids, cimetidine, PPIs, sucralfate, oral Fe, Ca salts, phosphate binders (e.g. sevelamer), bile acid sequestrants (e.g. colestyramine, colestipol), ion exchange resins (e.g. sodium polystyrene sulfonate), and orlistat. Risk of marked tachycardia and hypertension with ketamine. May decrease the effects of digitalis glycosides. Increased risk of cardiac arrhythmias and CNS stimulation with TCAs (e.g. amitriptyline). May result in false low plasma concentration when given with anti-inflammatory agents (e.g. aspirin, phenylbutazone). May increase the effects of anticoagulants (e.g. warfarin) and sympathomimetic agents (e.g. phenylephrine, epinephrine). Sertraline, tyrosine kinase inhibitors (e.g. imatinib), and estrogen derivatives may reduce the effects of levothyroxine sodium. Androgens and corticosteroids may decrease the levothyroxine-binding globulins serum levels. Peripheral conversion of levothyroxine sodium to triiodothyronine may be inhibited by amiodarone and β-blockers (e.g. propranolol), resulting in reduced efficacy. May cause an increase in dose requirements of antidiabetic drugs.

Thyroid Hormones

H03AA01 - levothyroxine sodium ; Belongs to the class of thyroid hormones.