SAFE

Consuming alcohol with Thyrox 25 does not cause any harmful side effects.

SAFE IF PRESCRIBED

Thyrox 25 is safe to use during pregnancy. Most studies have shown low or no risk to the developing baby.

SAFE IF PRESCRIBED

Thyrox 25 is safe to use during breastfeeding. Human studies suggest that the drug does not pass into the breastmilk in a significant amount and is not harmful to the baby.

SAFE

Thyrox 25 does not usually affect your ability to drive.

CONSULT YOUR DOCTOR

There is limited information available on the use of Thyrox 25 in patients with kidney disease. Please consult your doctor.

CONSULT YOUR DOCTOR

There is limited information available on the use of Thyrox 25 in patients with liver disease. Please consult your doctor.

Medicine Overview of Thyrox 25 25mcg Tablet

Introduction

Thyrox 25 is a medicine used to treat an underactive thyroid gland (hypothyroidism). It replaces the hormone which was not being produced by your thyroid gland in sufficient quantity and helps regulate your body’s energy and metabolism. Before you ...

Uses of Thyrox 25

Hypothyroidism

Side effects of Thyrox 25

Common

Palpitations

Vomiting

Anxiety

Diarrhea

Flushing (sense of warmth in the face, ears, neck and trunk)

Weight loss

Nervousness

Restlessness

How to use Thyrox 25

Take this medicine in the dose and duration as advised by your doctor. Swallow it as a whole. Do not chew, crush or break it. Thyrox 25 is to be taken empty stomach.

How Thyrox 25 works

Thyrox 25 is a synthetic version of a hormone produced by the thyroid gland. It works by replacing the thyroid hormones that your thyroid gland cannot produce in a sufficient quantity, and relieves the symptoms of hypothyroidism (tiredness, weight gain, and depression).

What if you forget to take Thyrox 25?

If you miss a dose of Thyrox 25, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Quick Tips

Thyrox 25 should be taken on an empty stomach (ideally, first thing in the morning). No food, milk, or tea should be taken 1 hour before and 2 hours after taking this medicine.

It may take 6 to 8 weeks to get the full effect.

For most people, Thyrox 25 can be a lifelong medication. Do not discontinue it without discussing your doctor.

Inform your doctor if you have diarrhea, nervousness, irritability, sleep disturbances, shaking hands, or chest pain. Your doctor may adjust your dose.

Leave a gap of at least 4 hours before taking any antacids, calcium or iron supplements, and multivitamins, as these may interfere with the effect of the medicine.

Get your hormone levels checked regularly and inform your doctor if you notice a significant change in your body weight. The dose may need to be adjusted.

Inform your doctor before changing the brand of Thyrox 25 as all brands may not have the same effect.

Brief Description

Indication

Hypothyroidism, TSH suppression, Myxoedema coma

Administration

Should be taken on an empty stomach with full glass of water. Take on an empty stomach ½-1 hr before meals.

Adult Dose

Oral Mild Hypothyroidism 1.7 mcg/kg or 100-125 mcg PO qDay; not to exceed 300 mcg/day >50 years (or <50 yr with CV disease) Usual initial dose: 25-50 mcg/day May adjust dose by 12.5-25 mcg q6-8Week >50 years with CV disease Usual initial dose: 12.5-25 mcg PO qDay May adjust dose by 12.5-25 mcg q4-6weeks until patient becomes euthyroid and serum TSH concentration normalized; adjustments q6-8weeks also used Dose range: 100-125 mcg PO qDay Severe Hypothyroidism Initial: 12.5-25 mcg PO qDay Adjust dose by 25 mcg/day q2-4Week PRN Subclinical Hypothyroidism Initial: 1 mcg/kg PO qDay may be adequate, OR If replacement therapy not initiated, monitor patient annually for clinical status TSH suppression For thyrotropin-dependent well-differentiated thyroid cancer: Doses >2 mcg/kg/day may be given as a single dose to suppress TSH to <0.1 MIU/L. For benign nodules and nontoxic multinodular goitre: Target TSH is generally higher at 0.1-0.5 MIU/L for nodules and 0.5-1 MIU/L for multinodular goitre.

Child Dose

Oral Hypothyroidism Age 1-3 months 10-15 mcg/kg/day PO Use lower starting dose (25 mcg/day) if patient at risk of cardiac failure; if initial serum T4 lower than 5 mcg/dL begin treatment at higher dose (50 mcg/day) Age 3-6 months 8-10 mcg/kg/day PO, OR 25-50 mcg/day PO Age 6-12 months 6-8 mcg/kg/day PO, OR 50-75 mcg/day PO Age 1-5 years 5-6 mcg/kg/day PO, OR 75-100 mcg/day PO Age 6-12 years 4-5 mcg/kg/day PO, OR 100-125 mcg/day PO >12 years 2-3 mcg/kg/day PO, OR 150 mcg/day PO Start children with severe or chronic hypothyroidism at 25 mcg/day; adjust dose by 25 mcg qweek

Contraindication

Untreated hyperthyroidism; uncorrected adrenal failure; recent MI.

Mode of Action

Levothyroxine Na is a synthetic form of thyroxine which increases the basal metabolic rate (BMR) and the utilisation and mobilisation of glycogen stores and stimulates protein synthesis. It is also involved in normal metabolism, growth and development. These effects are mediated at the cellular level by the thyroxine metabolite, tri-iodothyronine.

Precaution

Patients w/ CV (e.g. angina, heart failure, HTN), DM and diabetes insipidus, epilepsy, pre-existing myasthenia syndrome, long-standing hypothyroidism. Elderly, pregnancy and lactation. Monitoring Parameters Monitor thyroid function test, clinical signs of hypo- and hyperthyroidism, heart rate and BP. Lactation: Enters breast milk; use caution

Side Effect

Nervousness, excitability, tremor, muscle weakness, fatigue, cramps; sweating, flushing, heat intolerance, headache, fever, insomnia, tachycardia, palpitations, restlessness, anginal pain, HTN, severe depression, difficulty in sleeping, excessive wt loss; menstrual irregularities; diarrhoea, vomiting, psychosis or agitation. Increased bone resorption and reduced bone mineral density, especially in post-menopausal women; elevated LFT. Potentially Fatal: Thyrotoxic crisis including convulsions, cardiac arrhythmia, heart failure, coma.

Interaction

Reduced absorption w/ iron, antacids, bile acid sequestrants, colestyramine, simeticone, Ca carbonate, sucralfate, cation exchange resins. Reduced tri-iodothyronine serum levels w/ amiodarone and propranolol. Reduced serum levels of thyroxine w/ carbamazepine, phenytoin, phenobarbital, rifampicin, lithium, oestrogens, sertraline. Androgens may decrease levothyroxine-binding globulins serum levels. May alter requirements of antidiabetic drugs. Increased risk of significant HTN and tachycardia w/ ketamine. Increased metabolic demands w/ sympathomimetics (e.g. epinephrine). May increase anticoagulant effect of warfarin.