Tirosint-Sol Dosage

Generic name: LEVOTHYROXINE SODIUM 13ug in 1mL
Dosage form: oral solution
Drug class: Thyroid drugs

Medically reviewed by Drugs.com. Last updated on Oct 23, 2024.

General Administration Information

Administer TIROSINT-SOL as a single daily oral dose, on an empty stomach,15 minutes before breakfast.

Administer TIROSINT-SOL at least 4 hours before or after drugs known to interfere with TIROSINT-SOL absorption .

Evaluate the need for dose adjustments when regularly administering within an hour of certain foods that may affect TIROSINT-SOL absorption .

TIROSINT-SOL may be administered in water or directly into the mouth:

To administer TIROSINT-SOL in water, squeeze the contents of one single unit-dose ampule into a glass or cup containing water. Stir the diluted TIROSINT-SOL and drink all of it immediately. Rinse the glass or cup with additional water and drink the contents to ensure that the total dose is taken. Do not dilute TIROSINT-SOL in a medium other than water. Open the ampule and prepare the solution immediately before intake.
To administer TIROSINT-SOL directly (without water), either squeeze it into the mouth OR onto a spoon and immediately consume.

Important Considerations for Dosing

The dosage of TIROSINT-SOL for hypothyroidism or pituitary TSH suppression depends on a variety of factors including: the patient's age, body weight, cardiovascular status, concomitant medical conditions (including pregnancy), concomitant medications, co-administered food, and the specific nature of the condition being treated . Dosing must be individualized to account for these factors and dosage adjustments made based on periodic assessment of the patient's clinical response and laboratory parameters .

For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal.

For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of TIROSINT-SOL dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate TIROSINT-SOL dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range.

The peak therapeutic effect of a given dose of TIROSINT-SOL may not be attained for 4 to 6 weeks.

Recommended Dosage and Titration

Primary, Secondary, and Tertiary Hypothyroidism in Adults

The recommended starting daily dosage of TIROSINT-SOL in adults with primary, secondary, or tertiary hypothyroidism is based on age and comorbid cardiac conditions, as described in Table 1. For patients at risk of atrial fibrillation or patients with underlying cardiac disease, start with a lower dosage and titrate the dosage more slowly to avoid exacerbation of cardiac symptoms. Dosage titration is based on serum TSH or free-T4.

Table 1. TIROSINT-SOL Dosing Guidelines for Hypothyroidism in Adults*

Patient Population	Starting Dosage	Dosage Titration Based on Serum TSH or Free-T4
Adults diagnosed with hypothyroidism	Full replacement dose is 1.6 mcg/kg/day. Some patients require a lower starting dose.	Titrate dosage by 12.5 to 25 mcg increments every 4 to 6 weeks, as needed until the patient is euthyroid.
Adults at risk for atrial fibrillation or with underlying cardiac disease	Lower starting dose (less than 1.6 mcg/kg/day)	Titrate dosage every 6 to 8 weeks, as needed until the patient is euthyroid.
Geriatric patients	Lower starting dose (less than 1.6 mcg/kg/day)

*Dosages greater than 200 mcg/day are seldom required. An inadequate response to daily dosages greater than 300 mcg/day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors.

Primary, Secondary, and Tertiary Hypothyroidism in Pediatric Patients

The recommended starting daily dosage of TIROSINT-SOL in pediatric patients with primary, secondary, or tertiary hypothyroidism is based on body weight and changes with age as described in Table 2. Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid.

Table 2. TIROSINT-SOL Dosing Guidelines for Hypothyroidism in Pediatric Patients

Age	Starting Daily Dosage 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
Greater than 12 years but growth and puberty incomplete	2-3 mcg/kg/day
Growth and puberty complete	1.6 mcg/kg/day

*Adjust dosage based on clinical response and laboratory parameters.

Pediatric Patients from Birth to 3 Months of Age at Risk for Cardiac Failure

Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response.

Pediatric Patients at Risk for Hyperactivity

To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached.

Hypothyroidism in Pregnant Patients

For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.

The recommended daily dosage of TIROSINT-SOL in pregnant patients is described in Table 3.

Table 3. TIROSINT-SOL Dosing Guidelines for Hypothyroidism in Pregnant Patients

Patient Population	Starting Dosage	Dose Adjustment and Titration
Pre-existing primary hypothyroidism with serum TSH above normal trimester-specific range	Pre-pregnancy dosage may increase during pregnancy	Increase TIROSINT-SOL dosage by 12.5 to 25 mcg per day. Monitor TSH every 4 weeks until a stable dose is reached and serum TSH is within normal trimester-specific range. Reduce TIROSINT-SOL dosage to pre-pregnancy levels immediately after delivery. Monitor serum TSH 4 to 8 weeks postpartum.
New onset hypothyroidism TSH > 10 mIU per liter)	1.6 mcg/kg/day	Monitor serum TSH every 4 weeks and adjust TIROSINT-SOL dosage until serum TSH is within normal trimester-specific range.
New onset hypothyroidism (TSH < 10 mIU per liter)	1.0 mcg/kg/day

TSH Suppression in Well-differentiated Thyroid Cancer in Adults and Pediatric Patients

The TIROSINT-SOL dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer.

Monitoring TSH and/or Thyroxine (T4) Levels

Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation. Persistent clinical and laboratory evidence of hypothyroidism, despite an apparent adequate replacement dose of TIROSINT-SOL, may be evidence of inadequate absorption, poor compliance, drug interactions, or a combination of these factors.

Adults

In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient's clinical status.

Pediatrics Patients

In patients with hypothyroidism, assess the adequacy of replacement therapy by measuring both serum TSH and total or free-T4. Monitor TSH and total or free-T4 in pediatric patients as follows: 2 and 4 weeks after the initiation of treatment, 2 weeks after any change in dosage, and then every 3 to 12 months thereafter following dosage stabilization until growth is completed. Poor compliance or abnormal values may necessitate more frequent monitoring. Perform routine clinical examination, including assessment of mental and physical growth and development, and bone maturation, at regular intervals.

The general aim of therapy is to normalize the serum TSH level. TSH may not normalize in some patients due to in utero hypothyroidism causing a resetting of pituitary-thyroid feedback. Failure of the serum T4 to increase into the upper half of the normal range within 2 weeks of initiation of TIROSINT-SOL therapy and/or of the serum TSH to decrease below 20 mIU per Liter within 4 weeks may indicate the patient is not receiving adequate therapy. Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of TIROSINT-SOL .

Secondary (Pituitary) and Tertiary (Hypothalamic) Hypothyroidism

Monitor serum free-T4 levels and maintain in the upper half of the normal range in these patients.