Thyvex-50/Thyvex-100

Levothyroxine Na

Control of hypothyroidism. Congenital hypothyroidism in infants; acquired hypothyroidism & juvenile myxoedema in childn.

Adult Initially 100 mcg daily preferably taken before breakfast or 1st meal of the day. Adjust at 3-4 wk intervals by 50 mcg until normal metabolism is steadily maintained. Final daily dose: 100-200 mcg. Elderly >50 yr Initially, not advisable to exceed 50 mcg daily. Daily dose may be increased by 50 mcg at intervals of every 3-4 wk, until stable thyroxine levels are attained. Final daily dose: 50-200 mcg. Patient >50 yr w/ cardiac disease 25 mcg or 50 mcg on alternate days. May increase daily dose by 25 mcg at 4-wk intervals. Final daily dose: 50-200 mcg. Childn Maintenance dose: 100-150 mcg/m². Dose for childn depends on age, wt & condition being treated. Infants Total daily dose at least ½ an hr before the meal 1st meal of the day. Acquired hypothyroidism Initially 12.5-50 mcg/day, increased gradually every 2-4 wk according to clinical findings & thyroid hormone & TSH values until full replacement dose is reached. Juvenile myxoedema Initially 25 mcg daily. May increase by 25 mcg at 2-4 wk intervals until mild symptoms of hypothyroidism are seen. Infant Congenital hypothyroidism Initially 10-15 mcg/kg for the 1st 3 mth.

Should be taken on an empty stomach.

Hypersensitivity. Thyrotoxicosis, adrenal gland disorder or adrenal insufficiency.

Gradually introduce levothyroxine in patients >50 yr & those w/ long standing hypothyroidism to avoid sudden increase in metabolic demands. Start corticosteroid therapy before administration in patients w/ panhypopituitarism or other causes predisposing to adrenal insufficiency. Patients w/ CV disorders, including angina, CAD, HTN, & in the elderly w/ greater likelihood of occult cardiac disease; symptoms of myocardial insufficiency, or ECG evidence of MI; DM, diabetes insipidus. History of epilepsy, seizures rarely in association w/ initiation of levothyroxine Na therapy & may be related to the effect of thyroid hormone on seizure threshold. May cause an increase in dosage requirements of insulin or other anti-diabetic therapy (eg, metformin). Avoid in patients w/ galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption. Risk of osteoporosis. Partial hair loss may occur during the 1st few months of therapy. Monitor serum TSH & adjust the dose accordingly during long term use in older patients w/ atrial fibrillation & fractures associated w/ low serum levels of TSH. Perform an ECG prior to commencement of levothyroxine treatment in individuals suspected to have CV disease or to be at high risk. Administration of whole tab is not recommended in childn <5 yr. Pregnancy.

Hypersensitivity reaction; thyrotoxic crisis; restlessness, agitation, insomnia; tremor; angina pectoris, arrhythmia, palpitations, tachycardia; flushing; dyspnoea; diarrhoea, vomiting; hyperhidrosis, rash, pruritus; arthralgia, muscle spasm, muscular weakness; irregular menstruation; headache, pyrexia, malaise, oedema; decreased wt. Childn: Heat intolerance, transient hair loss, benign intracranial HTN, craniostenosis in infants & premature closure of epiphysis in childn.

Increases effect of warfarin. Blood sugars are raised & dose of anti-diabetic agents may require adjustment. May precipitate cardiac arrhythmias w/ TCAs (eg, amitriptyline, imipramine, dosulepin). Enhanced effects of sympathomimetic agents (eg, adrenaline or phenylephrine). Cardiac glycosides. False low plasma conc w/ concurrent anti-inflammatory treatment eg, phenylbutazone or acetylsalicylic acid. Accelerates metabolism of propranolol, atenolol & sotalol. Reduced effects of thyroid hormones w/ amiodarone. Enhanced metabolism of thyroid hormones & may displace from plasma proteins w/ anti-convulsants eg, carbamazepine & phenytoin. Decreased effect w/ sertraline. Reduced absorption w/ antacids, proton pump inhibitors, Ca salts, cimetidine, oral Fe, sucralfate, colestipol, polystyrene sulphonate resin & cholestyramine; anti-obesity drugs. Accelerated metabolism w/ rifampicin, barbiturates, & primidone. Reduced plasma conc w/ imatinib. Decreased peripheral conversion to triiodothyronine w/ β-blockers. Lipid regulating drugs. May increase the requirement of thyroid therapy dosage & increased serum TBG conc w/ oestrogen, oestrogen containing product (including hormone replacement therapy) & OCs. May decrease serum conc w/ androgens & corticosteroids. Potential interaction between ritonavir containing products. May decrease absorption from the GI tract w/ soybean flour (infant formula), cotton seed meal, walnuts, Ca & Ca-fortified orange juice, & dietary fibre.

Thyroid Hormones

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

Rx