Thyronor
Levothyroxine Sodium
Dosage Form: TabletPack Size: 3 X 35's
Composition:
THYRONOR® 12.5 Tablet: Each tablet contains Levothyroxine Sodium USP 12.5 mcg.
THYRONOR® 25 Tablet: Each tablet contains Levothyroxine Sodium USP 25 mcg.
THYRONOR® 50 Tablet: Each tablet contains Levothyroxine Sodium USP 50 mcg.
THYRONOR® 75 Tablet: Each tablet contains Levothyroxine Sodium USP 75 mcg.
THYRONOR® 100 Tablet: Each tablet contains Levothyroxine Sodium USP 100 mcg.
THYRONOR® contains synthetic Levothyroxine (also called Thyroxine or T4) which is
identical to the natural hormone T4, produced in the thyroid gland. About 30 % of T4 is
converted to the much more active Triiodothyronine (T3) in peripheral tissues. TBG
(Thyroxine Binding Globulin) is the major carrier of T4. This binding protects T4 from
metabolism and excretion resulting in its long half-life in the circulation. Only about 0.03
% of total T4 in plasma is unbound. The half-life of elimination of T4 is 6 to 7 days. In
hyperthyroidism, the half-life is shortened to 3 or 4 days, whereas in hypothyroidism it may
be 9 to 10 days. In conditions associated with reduced protein in plasma as in nephrosis or
hepatic cirrhosis or when binding to protein is inhibited by certain drugs the half-life of T4
may be shortened. The liver is the major site of degradation of Thyroid hormones. T4 is
conjugated with Glucuronic and Sulphate conjugates through the Phenolic hydroxyl group
and excreted in the urine. There is an enterohepatic circulation of the Thyroid hormones,
since they are liberated by hydrolysis in the intestine and reabsorbed. Because of the long
half-life of T4, a steady blood level of the biologically more active T3 can be obtained from
one single daily dose of THYRONOR®. Therefore, variations in the therapeutic effect are
unlikely once the correct dosage has been established.
Indications:
As replacement therapy in hypothyroidism of any etiology. Replacement therapy should
not be instituted in transient hypothyroidism during the recovery phase of subacute
Thyroiditis
For the suppression of Thyroid Stimulating Hormone (TSH) levels in the presence of
goitres, nodules and after radiological and/or surgical treatment of thyroid cancer
For the suppression of the goitrogenic effects of other drugs such as Lithium
As a diagnostic aid in suppression tests
Dosage & Administration:
Adult Dosage:
Initial starting dose: 25-50 mcg/day, with gradual increments in dose at 6-8 week
intervals, as needed. The Levothyroxine Sodium dose is generally adjusted in 12.5-25 mcg
increments until the patient with primary hypothyroidism is clinically euthyroid and the
serum TSH has normalized.
In patients with severe hypothyroidism: Initial dose is 12.5-25 mcg/day with increases
of 25 mcg/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 mcg/kg/day.
Pediatric Dosage:
Newborns: The recommended starting dose is 10-15 mcg/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 of Levothyroxine Sodium is 50 mcg/day.
Infants and Children: In children with chronic or severe hypothyroidism, initial dose of 25
mcg/day with increments of 25 mcg 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.
Daily dose per kg body weight:
0-3 months: 10-15 mcg/kg/day
3-6 months: 8-10 mcg/kg/day
6-12 months: 6-8 mcg/kg/day
1-5 years: 5-6 mcg/kg/day
6-12 years: 4-5 mcg/kg/day
>12 years but growth and puberty incomplete: 2-3 mcg/kg/day
Growth and puberty complete: 1.7 mcg/kg/day
The dose should be adjusted based on clinical response and laboratory parameters.
Contraindications:
- Untreated subclinical or overt Thyrotoxicosis of any etiology
• Acute Myocardial Infarction
• Uncorrected Adrenal failure
Warning & Precautions:
• In patients whose hypothyroidism is due to a decrease in pituitary gland function, there
may also be adrenocortical insufficiency; before starting THYRONOR® 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
development or worsening of angina complaints, arrhythmias, myocardial infarction,
cardiac failure or to 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 THYRONOR® 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
Overdose:
The signs and symptoms of overdose are those of hyperthyroidism - agitation, confusion,
irritability, hyperactivity, headache, sweating, mydriasis, tachycardia, arrhythmias,
tachypnoea, pyrexia, increased bowel movements and convulsions. Cerebral embolism,
shock, coma, and death have been reported. Symptoms may not necessarily be evident or
may not appear until several days after ingestion of Levothyroxine Sodium.
Treatment of Overdose: Dose of Levothyroxine Sodium should be reduced or temporarily
discontinued if signs or symptoms of overdosage occur. Treatment is symptomatic.
Storage Conditions:
Store below 30_C. & dry place. Keep away from light and out of the reach of children.
Commercial Pack:
THYRONOR® 12.5 Tablet: Each box contains 105 tablets in 3 x 35’s Alu-PVDC blister
strips in a sachet.
THYRONOR® 25 Tablet: Each box contains 105 tablets in 3 x 35’s Alu-PVDC blister strips
in a sachet.
THYRONOR® 50 Tablet: Each box contains 105 tablets in 3 x 35’s Alu-PVDC blister strips
in a sachet.
THYRONOR® 75 Tablet: Each box contains 105 tablets in 3 x 35’s Alu-PVDC blister strips
in a sachet.
THYRONOR® 100 Tablet: Each box contains 105 tablets in 3 x 35’s Alu-PVDC blister
strips in a sachet.