Thyroxine Pharmacology

Thyroxine

About Thyroxine
Thyroid hormone, Replacement or supplemental therapy in hypothyroidism.
Mechanism of Action of Thyroxine
Thyroid hormones; Thyroxine (T4) and Triiodothyronine (T3) exert the therapeutic action by regulating protein synthesis. T4 and T3 enter the cells and combine with nuclear receptor. T3 receptor complex binds to specific DNA sequence called "thyroid hormone response elements" present in the regulatory region of specific genes and causes derepression of gene transcription or direct activation of gene transcription. Thus causes expression of predetermined genetically coded pattern of protein synthesis. It causes induction of adenylyl cyclase and proliferation of ?-adrenoceptors and a better coupling of these two. It regulate growth, development, improves carbohydrate utilization and BMR.

Pharmacokinets of Thyroxine
Absorption: Well absorbed orally, Distribution: Widely distributed in a protein bound form, Metabolism: Metabolized primarily in liver by deiodination, glucuronide and sulfate conjugation. Also metabolized in salivary glands and kidneys. Excretion: Excreted through faeces and urine.
Onset of Action for Thyroxine
N/A
Duration of Action for Thyroxine
N/A
Half Life of Thyroxine
T4: 6 to 7days
T3: 1 to 2 days
Side Effects of Thyroxine
1. Tachycardia
2. Arrhythmia
3. Increased BP
4. Hyperglycaemia
5. Tremor
6. Palpitation
7. Angina
8. Cardiac arrest
9. Osteoporosis
10. Thyrotoxicosis
11. Headache
12. Weakness
13. Weight loss
14. Allergic reactions
15. Diarrhoea
16. Vomiting
17. Sweating
18. Restlessness
19. Insomnia
20. Heat intolerance
21. Fever
22. Menstrual irregularities
Contra-indications of Thyroxine
1. Hypersensitivity
2. Thyrotoxicosis
3. Cardiac disease
4. Acute myocardial infarction
5. Adrenal insufficiency
Special Precautions while taking Thyroxine
1. Angina pectoris
2. Coronary artery diseases
3. Hypertension
4. Ischaemia
5. Renal impairment
6. ECG changes
7. In adrenal insufficiency give corticosteroid therapy prior to Thyroxine therapy
Pregnancy Related Information
Use with caution
Old Age Related Information
Use with in caution
Breast Feeding Related Information
Use with caution
Children Related Information
Use with caution
Indications for Thyroxine
1. Cretinism
2. Hypothyroidism
3. Myxoedema
4. Nontoxic goiter
5. Benign functioning thyroid nodule
6. Temporary regression of papillary carcinoma of thyroid
Interactions for Thyroxine
N/A
Typical Dosage for Thyroxine
Oral: Starts with 50 to 100mcg. Increased by increments of 25 to 50mcg at intervals of 3 to 4 weeks; as required by the patient.
Maximum daily dose: 0.15 to 0.3mg
Children: 25 to 150 mcg/day depending up on the requirement of the patient. Increased by increments of 25mcg every 2 to 4 weeks.
Juvenile myxoedema:
Children over 1year: Initially 2. to 5mcg/kg/day
Schedule of Thyroxine
C1
Storage Requirements for Thyroxine
Store in a refrigerator
Effects of Missed Dosage of Thyroxine
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Thyroxine
Treatment is supportive and symptomatic. Remove drug from the body by gastric lavage and induced emesis. Administer activated charcoal to reduce absorption. If patient is in a coma state inflate cuff on endotrachaeal tube to prevent aspiration. Assist and support respiration if required. Take appropriate measures to control heart failure and control fever, hypoglycaemia and fluid loss. Propranolol or any other beta blocker may be used to correct increased sympathetic activity.

Home Delivery for Thyroxine in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including thyroxine.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for thyroxine and other medicines and health products. Home delivery services for thyroxine may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take thyroxine only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for thyroxine before they complete the sale. You can get this information while placing the order for thyroxine with the pharmacy.

Thyroxine is a generic medicine name and there are several brands available for it. Some of the brands for thyroxine might be better known than thyroxine itself. If the pharmacy that's willing to deliver medicines to your home doesn't have thyroxine in stock, you can ask for one of the branded alternatives for thyroxine.