Administer levothyroxine sodium tablets to pediatric patients who cannot swallow intact tablets by crushing the tablet, suspending the freshly crushed tablet in a small amount (5 to 10 mL) of water and immediately administering the suspension by spoon or dropper. Ensure the patient ingests the full amount of the suspension. Do not store the suspension. Do not administer in foods that decrease absorption of levothyroxine sodium tablets, such as soybean-based infant formula [see Drug Interactions (7.9)].
The dosage of levothyroxine sodium tablets 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 [see Dosage and Administration (2.3), Warnings and Precautions (5), and Drug Interactions (7)]. 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 [see Dosage and Administration (2.4)]. For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal [see Dosage and Administration (2.3)].
For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of levothyroxine sodium tablets dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate levothyroxine sodium tablets dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range [see Dosage and Administration (2.3)].
Inquire whether patients are taking biotin or biotin-containing supplements. If so, advise them to stop biotin supplementation at least 2 days before assessing TSH and/or T4 levels [see Dosage and Administration (2.4) and Drug Interactions (7.10)].
The peak therapeutic effect of a given dose of levothyroxine sodium tablets may not be attained for 4 to 6 weeks.