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SYSTEMIC HORMONAL PREPARATIONS, EXCL. SEX HORMONES AND INSULINS › THYROID THERAPY › THYROID PREPARATIONS › Thyroid hormones
levothyroxine sodium and iodine compounds
H03AA51
Forms & Strengths
- Combination oral preparations containing synthetic levothyroxine sodium and iodine compounds (e.g., potassium iodide), varying by specific regional or historical product formulations.
Adult Dosing
- Individualized based on clinical response and thyroid function tests (TSH, free T4).
- Typically initiated at low doses and titrated gradually every 4-6 weeks until euthyroid state is achieved.
Pediatric Dosing
- Dosing must be carefully individualized based on age, body weight, and severity of deficiency.
- Pediatric formulations require strict monitoring of growth, development, and thyroid hormone levels.
Indications
- Replacement therapy in hypothyroidism of various etiologies.
- Suppression of thyrotropin (TSH) in the treatment or prevention of various types of euthyroid goiters.
- Specific combined iodine and thyroid hormone supplementation where indicated.
Mechanism of Action
- Levothyroxine acts as a synthetic T4, converted in peripheral tissues to T3, binding to thyroid hormone receptors to regulate metabolic rate, growth, and development.
- Iodine compounds provide the necessary substrate for endogenous thyroid hormonogenesis and inhibit excessive thyroid hormone release in certain clinical contexts.
Contraindications
- Hypersensitivity to any component of the formulation.
- Untreated subclinical or overt thyrotoxicosis.
- Uncorrected adrenal insufficiency.
Adverse Reactions
- Symptoms of hyperthyroidism due to overdosage: weight loss, tachycardia, palpitations, cardiac arrhythmias, hypertension, tremors, insomnia, headache, diarrhea, and heat intolerance.
- Allergic reactions to iodine or excipients.
Drug Interactions
- Oral anticoagulants: enhanced hypoprothrombinemic effect.
- Antidiabetic agents: decreased efficacy, requiring dosage adjustment of antidiabetic drugs.
- Cholestyramine, colestipol, and calcium/iron supplements: decreased absorption of levothyroxine.
- Amiodarone, lithium, and iodinated contrast media: may alter thyroid function and response to therapy.
Curated Content: Needs Vetting Before Put to Clinical Use