LEVOTHOX

What it is

LEVOTHOX contains levothyroxine sodium as the active ingredient. LEVOTHOX is used as thyroid replacement therapy for the treatment of hypothyroidism. The principal pharmacological effect of thyroid hormones is to increase the metabolic rate of body tissues. LEVOTHOX is bioequivalent to ELTROXIN. LEVOTHOX is not bioequivalent on a same-dose basis with other levothyroxine containing products.

Approved indications

— Management of demonstrated thyroid hormone deficiency. — TSH suppression for the management of TSH-responsive tumours of the thyroid.

Dosing overview

Levothyroxine is best taken as a single daily dose first thing in the morning. It should be taken with water and on an empty stomach, and at least 30 minutes and preferably 60 minutes before the intake of any food or other medications. **Adults.** Commence with levothyroxine 50 to 100 micrograms daily. Increase the daily dose by 25 to 50 micrograms according to response at not less than 4-weekly intervals, up to 100 to 200 micrograms daily. In patients aged 60 years and over and in those with ischaemic heart disease, levothyroxine therapy should normally be initiated with low doses (25 or 50 µg/day). Maintenance doses for adults are 100 to 200 µg per day. **Children.** For congenital and acquired hypothyroidism, levothyroxine dosing by age is approximately 8 µg/kg/day for ages 0–6 months, 6 µg/kg/day for ages 6–12 months, 5 µg/kg/day for ages 1–5 years, 4 µg/kg/day for ages 6–12 years, and 2 µg/kg/day for ages 12 years and over.

Key safety warnings

Do not interchange LEVOTHOX and other levothyroxine containing products. If a decision is made to switch from another levothyroxine product to LEVOTHOX, then prescribers should be aware that dose adjustment may be required; TSH should be monitored. Extreme caution is required in patients with a cardiovascular disorder. In the event of cardiovascular effects, the dosage of LEVOTHOX should be lowered. Even smaller initial dosage (e.g. 12.5 to 25 µg/day) should be used with increments of not more than 25 µg/day at not less than two weeks intervals. If this routine is not tolerated because of angina, increments should be further reduced with prolongation of the intervals between changes. Corticosteroid replacement therapy must precede initiation of LEVOTHOX therapy to avoid Addisonian crisis in such conditions as hypopituitarism and adrenal insufficiency. In women, long-term levothyroxine sodium therapy has been associated with increased bone resorption, thereby decreasing bone mineral density, especially in post-menopausal women on greater than replacement doses or in women who are receiving suppressive doses of levothyroxine sodium. Caution is also required when levothyroxine is given to hypothyroid patients with diabetes mellitus or diabetes insipidus, as it may cause the required dosage of insulin and oral antidiabetic agents to be increased. Careful monitoring of diabetic control is recommended, especially when LEVOTHOX therapy is initiated, changed or discontinued.

Contraindications

LEVOTHOX is contraindicated in known hypersensitivity to thyroxine, untreated hyperthyroidism, uncorrected primary or secondary adrenal insufficiency, thyrotoxicosis, acute myocardial infarction uncomplicated by hypothyroidism, acute myocarditis, and acute pancarditis. During pregnancy, combination of levothyroxine and antithyroid agents for the treatment of hyperthyroidism is contraindicated.

Regulatory history

LEVOTHOX was first approved on 25 July 2022. ARTG registrations for LEVOTHOX levothyroxine sodium tablets in strengths ranging from 25 to 200 micrograms in blister and bottle formats were all first listed on 2022-07-25.