Levothyroxine Sodium (Page 2 of 8)

2.4 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 levothyroxine sodium tablets 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.

Pediatric 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 development, mental and physical growth, 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 levothyroxine sodium tablet therapy and/or of the serum TSH to decrease below 20 international unit 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 levothyroxine sodium tablets [see Warnings and Precautions (5.1) and Use in Specific Populations (8.4)].

Secondary and Tertiary Hypothyroidism

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

3 DOSAGE FORMS AND STRENGTHS

Levothyroxine sodium tablets, USP are available as follows (Table 4):

Table 4: Levothyroxine Sodium Tablets, USP Strength and Identifying Features

Tablet Strength

Tablet Color/Shape

Debossed Tablet Markings

25 mcg

Orange/Capsule Shaped

25 on the unscored side and T bisect V on the scored side, with side scores

50 mcg

White/Capsule Shaped

50 on the unscored side and T bisect V on the scored side, with side scores

75 mcg

Violet/Capsule Shaped

75 on the unscored side and T bisect V on the scored side, with side scores

88 mcg

Olive/Capsule Shaped

88 on the unscored side and T bisect V on the scored side, with side scores

100 mcg

Yellow/Capsule Shaped

100 on the unscored side and T bisect V on the scored side, with side scores

112 mcg

Rose/Capsule Shaped

112 on the unscored side and T bisect V on the scored side, with side scores

125 mcg

Brown/Capsule Shaped

125 on the unscored side and T bisect V on the scored side, with side scores

137 mcg

Turquoise/Capsule Shaped

137 on the unscored side and T bisect V on the scored side, with side scores

150 mcg

Blue/Capsule Shaped

150 on the unscored side and T bisect V on the scored side, with side scores

175 mcg

Lilac/Capsule Shaped

175 on the unscored side and T bisect V on the scored side, with side scores

200 mcg

Pink/Capsule Shaped

200 on the unscored side and T bisect V on the scored side, with side scores

300 mcg

Green/Capsule Shaped

300 on the unscored side and T bisect V on the scored side, with side scores


4 CONTRAINDICATIONS

Levothyroxine sodium tablets are contraindicated in patients with uncorrected adrenal insufficiency [see Warnings and Precautions (5.4)].

5 WARNINGS AND PRECAUTIONS

5.1 Serious Risks Related to Overtreatment or Undertreatment with Levothyroxine Sodium Tablets

Levothyroxine sodium tablets have a narrow therapeutic index. Overtreatment or undertreatment with levothyroxine sodium tablets may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, gastrointestinal function, and glucose and lipid metabolism in adult or pediatric patients.

In pediatric patients with congenital and acquired hypothyroidism, undertreatment may adversely affect cognitive development and linear growth, and overtreatment is associated with craniosynostosis and acceleration of bone age [see Use in Specific Populations (8.4)].

Titrate the dose of levothyroxine sodium tablets carefully and monitor response to titration to avoid these effects [see Dosage and Administration (2.4)]. Consider the potential for food or drug interactions and adjust the administration or dosage of levothyroxine sodium tablets as needed [see Dosage and Administration (2.1), Drug Interactions (7.1), and Clinical Pharmacology (12.3)].

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