Thyrox 50

Indications

As a replacement therapy for hypothyroidism caused by any cause. During the healing period of subacute Thyroiditis, replacement medication should not be started for transitory hypothyroidism. In the presence of goiters, nodules, and following radiological and/or surgical therapy of Thyroid cancer, to lower Thyroid Stimulating Hormone (TSH) levels. In order to reduce the goitrogenic effects.

 

Pharmacology

Thyrox 50 mg tablet includes synthetic Levothyroxine (commonly known as Thyroxine or T4), which is the same as the natural thyroid hormone T4. In peripheral tissues, about 30% of T4 is transformed to the far more active Triiodothyronine (T3). The principal carrier of T4 is TBG (Thyroxine Binding Globulin). Because of this binding, T4 is protected from metabolism and excretion, resulting in a lengthy half-life in the body.

 

Dosage & Administration

Adult dose:

• Initial starting dose: 25-50 meg/day, with gradual increments in dose at 6-8-week intervals, as needed. The Levothyroxine Sodium dose is generally adjusted in 12.5-25 meg increments until the patient with primary hypothyroidism is clinically euthyroid and the serum TSH has normalized.
• In patients with severe hypothyroidism: The initial dose is 12.5-25 mg/day with increases of 25 mg/day every 2-4 weeks, accompanied by clinical and laboratory assessment until the TSH level is normalized.
• In patients with secondary (pituitary) or tertiary (hypothalamic)
• hypothyroidism: Levothyroxine Sodium dose should be titrated until the patient is clinically euthyroid and the serum-free - T4 level is restored to the upper half of the normal range.
• For patients older than 50 years or for patients under 50 years of age with underlying cardiac disease: 1.7 mg/kg/day.

Pediatric Dosage Newborns: The recommended starting dose is 10-15 mg/kg/day. A lower starting dose should be considered in infants at risk for cardiac failure and the dose should be increased in 4-6 weeks as needed based on clinical and laboratory response to treatment. In infants with very low (<5 mcg/dL) or undetectable serum T4 concentrations, the recommended initial starting dose is 50 mg/day of Levothyroxine Sodium.

Infants and Children: In children with chronic or severe hypothyroidism, the initial dose of 25 mg/day with increments of 25 mg every 2-4 weeks until the desired effect is achieved. Hyperactivity in an older child can be minimized if the starting dose is one-fourth of the recommended full replacement dose and the dose is then increased on a weekly basis by an amount equal to one-fourth of the full recommended replacement dose until the full recommended replacement dose is reached.

• 0-3 months: 10-15 meg/kg/day
• 3-6 months: 8-10 meg/kg/day
• 6-12 months: 6-8 meg/kg/day
• 1-5 years: 5-6 meg/kg/day
• 6-12 years: 4-5 meg/kg/day
• >12 years but growth and puberty incomplete: 2-3 meg/kg/day
• Growth and puberty complete: 1.7 mg/kg/day.

The dose should be adjusted based on clinical response and laboratory parameters. In the treatment of goiters, nodules, and Thyroid cancer, the objective is to ensure a constant and sufficient suppression of TSH. For suppression of TSH levels, a gradual increase in dosing is usually not necessary. For adults, the usual suppressive dosage of T4 is 2.6 mg/kg of body weight daily. When Levothyroxine Sodium is used as a diagnostic aid, the dosage depends on the type of investigation.

 

Interaction

Concomitant use of Thyroid hormones with any of the following drugs or substances may lead to the occurrence of clinically relevant interactions:

• Oral anticoagulants: Thyroid hormones may enhance the activity of oral anticoagulants.
• Antidiabetic drugs: Thyroid hormones may cause increases in insulin or oral hypoglycaemic drug requirements.
• Digitalis preparations: Thyroid hormones may alter the requirement for Digitalis preparations.
• Cholestyramine: The absorption of Thyroid hormones may be decreased by Cholestyramine; therefore, there should be an interval of at least 4 hours between administration.
• Phenytoin: Phenytoin appears to enhance the metabolism of Thyroid hormones and may also displace T4 from TBG.
• Foods: In order to avoid irregular absorption Levothyroxine tablets should be taken preferably at a fixed time on an empty stomach with some fuilds. Simultaneous intake of food may decrease the absorption of T4.

 

Contraindications

Overdosing can cause hyperthyroidism symptoms like tachycardia, agitation, tremor, headache, flushing, perspiration, and weight loss. Treatment can be stopped for a few days and then resumed at a lower dose if necessary.

 

Pregnancy & Lactation

Category A Pregnancy. The need for Levothyroxine may increase during pregnancy. Although thyroid hormones are excreted in small amounts in human milk, caution should be maintained when given to a nursing mother. To maintain regular lactation, however, appropriate replacement doses of Levothyroxine are usually required.

 

Precautions & Warnings

• In patients whose hypothyroidism is due to a decrease in pituitary gland function, there may also be adrenocortical insufficiency; before starting Levothyroxine therapy, this should be treated by adequate replacement with Corticosteroids to prevent acute adrenal insufficiency.
• The choice of the starting dose and of any increases in dosing should be made with great care in patients with cardiovascular disease and/or severe and long-existing hypothyroidism. Too high an initial dose or too rapid an increase in dosing may lead to the development or worsening of angina complaints, arrhythmias, myocardial infarction, cardiac failure, or a sudden increase in blood pressure, especially in older patients.
• Any marked change of body weight during treatment with T4 requires adjustment of the dosage.
• When monitoring blood levels of T3 and T4, it should be borne in mind that a "high" normal to slightly increased T4 level will be necessary in order to obtain a normal level of T3. The correct dosage of Levothyroxine in primary hypothyroidism should generally be established by monitoring the serum level of TSH to see whether it has normalized.
• Because intoxication with Thyroid preparations may have serious consequences.

 

Therapeutic Class

Thyroid medications and hormones.

 

Storage Conditions

Protect from light and store in a cool, dry location. Keep out of children's reach.

 

Pharmaceutical Name

Renata Limited.

 

Generic

Levothyroxine Sodium.

 

Related Products

• Thyrin 50
• Thyronor 50