Thyrox
Generic Name
Levothyroxine Sodium
Manufacturer
Eskayef Pharmaceuticals Ltd.
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| thyrox 25 mcg tablet | ৳ 1.11 | ৳ 33.30 |
Description
Overview of the medicine
Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism (underactive thyroid) and to suppress thyroid-stimulating hormone (TSH) in patients with thyroid cancer or goiter.
Uses & Indications
Dosage
Adults
Initial dose usually 12.5-25 mcg orally once daily, gradually increased by 12.5-25 mcg every 4-6 weeks until TSH levels are normalized. Maintenance dose usually 50-200 mcg daily.
Elderly
Lower initial doses (e.g., 12.5 mcg daily) and slower titration may be required due to increased sensitivity and potential for cardiac effects.
Renal_impairment
No specific dosage adjustment is usually required.
How to Take
Take orally once daily, preferably on an empty stomach 30-60 minutes before breakfast, to ensure consistent absorption. Do not take with other medications or supplements at the same time.
Mechanism of Action
Levothyroxine acts as a synthetic replacement for endogenous thyroid hormones. It binds to thyroid hormone receptors in the cell nucleus, regulating gene expression and metabolism. It is converted to liothyronine (T3) in peripheral tissues, which is the active form.
Pharmacokinetics
Onset
Therapeutic effects are gradual, typically taking several weeks to achieve full effect. Clinical improvement may be seen within 3-5 days.
Excretion
Eliminated primarily through urine (about 80%) and feces (about 20%).
Half life
Approximately 6-7 days (euthyroid patients), 9-10 days (hypothyroid patients).
Absorption
Approximately 48-80% absorbed from the gastrointestinal tract, primarily in the jejunum and ileum. Absorption is affected by food and other medications.
Metabolism
Primarily deiodinated in the liver and kidney to T3 and reverse T3. Also undergoes conjugation with glucuronides and sulfates.
Side Effects
Contraindications
- Untreated subclinical or overt thyrotoxicosis
- Acute myocardial infarction
- Uncorrected adrenal cortical insufficiency
- Hypersensitivity to levothyroxine or any excipients
Drug Interactions
Warfarin
May increase anticoagulant effect.
Oral contraceptives containing estrogen
May increase thyroid hormone binding globulin, requiring a higher levothyroxine dose.
Bile acid sequestrants (e.g., cholestyramine, colestipol)
May decrease levothyroxine absorption. Separate administration by 4-5 hours.
Antacids (e.g., aluminum, magnesium), Iron supplements, Calcium supplements
May decrease levothyroxine absorption. Separate administration by at least 4 hours.
Storage
Store at room temperature (below 30°C), protected from light and moisture. Keep out of reach of children.
Overdose
Symptoms include tachycardia, palpitations, arrhythmia, tremor, headache, nervousness, irritability, insomnia, hyperhidrosis, weight loss, and increased appetite. Management involves supportive care, reduction/cessation of levothyroxine, and beta-blockers for cardiac symptoms.
Pregnancy & Lactation
Levothyroxine is generally safe and necessary during pregnancy and lactation. Hypothyroidism should be adequately treated to ensure healthy fetal development. Dosage may need to be increased during pregnancy. Minimal amounts are excreted in breast milk.
Side Effects
Contraindications
- Untreated subclinical or overt thyrotoxicosis
- Acute myocardial infarction
- Uncorrected adrenal cortical insufficiency
- Hypersensitivity to levothyroxine or any excipients
Drug Interactions
Warfarin
May increase anticoagulant effect.
Oral contraceptives containing estrogen
May increase thyroid hormone binding globulin, requiring a higher levothyroxine dose.
Bile acid sequestrants (e.g., cholestyramine, colestipol)
May decrease levothyroxine absorption. Separate administration by 4-5 hours.
Antacids (e.g., aluminum, magnesium), Iron supplements, Calcium supplements
May decrease levothyroxine absorption. Separate administration by at least 4 hours.
Storage
Store at room temperature (below 30°C), protected from light and moisture. Keep out of reach of children.
Overdose
Symptoms include tachycardia, palpitations, arrhythmia, tremor, headache, nervousness, irritability, insomnia, hyperhidrosis, weight loss, and increased appetite. Management involves supportive care, reduction/cessation of levothyroxine, and beta-blockers for cardiac symptoms.
Pregnancy & Lactation
Levothyroxine is generally safe and necessary during pregnancy and lactation. Hypothyroidism should be adequately treated to ensure healthy fetal development. Dosage may need to be increased during pregnancy. Minimal amounts are excreted in breast milk.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
Typically 2-3 years from manufacturing date.
Availability
Pharmacies and hospitals
Approval Status
Approved by regulatory bodies (e.g., FDA, DGDA)
Patent Status
Generic available, original patent expired
WHO Essential Medicine
YesClinical Trials
Extensively studied and validated for efficacy and safety in treating hypothyroidism and TSH suppression.
Lab Monitoring
- Serum TSH (Thyroid-Stimulating Hormone) levels
- Serum Free T4 (Thyroxine) levels
- Clinical evaluation of symptoms
Doctor Notes
- Emphasize consistent daily intake on an empty stomach.
- Monitor TSH levels every 6-8 weeks until stable, then annually.
- Counsel patients on potential drug and food interactions.
- Advise caution in elderly patients and those with cardiac conditions.
Patient Guidelines
- Take your medicine at the same time each day, preferably in the morning before breakfast.
- Do not take other medications, especially antacids, iron, or calcium supplements, within 4 hours of taking levothyroxine.
- Do not stop taking this medicine without consulting your doctor, even if you feel better.
- Regular blood tests (TSH) are essential to monitor your thyroid levels.
Missed Dose Advice
If a dose is missed, take it as soon as you remember, unless it is almost time for your next dose. Do not double the dose. If you miss several doses, consult your doctor.
Driving Precautions
No known direct adverse effects on the ability to drive or operate machinery. However, if experiencing side effects like tremor or nervousness, caution is advised.
Lifestyle Advice
- Maintain a balanced diet.
- Engage in regular physical activity.
- Manage stress effectively.
- Avoid sudden changes in diet or supplements without consulting your doctor.
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