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SYSTEMIC HORMONAL PREPARATIONS, EXCL. SEX HORMONES AND INSULINS › THYROID THERAPY › THYROID PREPARATIONS › Thyroid hormones
levothyroxine sodium
H03AA01
Forms & Strengths
- Tablets: 25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 112mcg, 125mcg, 137mcg, 150mcg, 175mcg, 200mcg
- Capsules: 13mcg, 26mcg, 52mcg, 104mcg, 156mcg, 208mcg
- Oral solution: 25mcg/5mL, 50mcg/5mL
- Injectable solution: 200mcg/1mL, 500mcg/1mL
Adult Dosing
- Hypothyroidism: 50-100mcg PO daily, adjust q6-8wk
- Myxedema coma: 200-500mcg IV x1, then 50-100mcg IV daily
- Thyroid suppression: 50-200mcg PO daily
Pediatric Dosing
- 0-3 months: 10-15mcg/kg/day PO
- 3-12 months: 8-10mcg/kg/day PO
- 1-5 years: 5-6mcg/kg/day PO
- 6-12 years: 4-5mcg/kg/day PO
- Greater than 12 years: 2-3mcg/kg/day PO
Indications
- Primary hypothyroidism
- Secondary hypothyroidism
- Tertiary hypothyroidism
- Simple goiter
- Thyroid suppression test
- Thyroid cancer
Mechanism of Action
- Exogenous thyroid hormone replacement
- Increases circulating T3 and T4 levels
- Enhances cellular metabolism and energy production
Contraindications
- Hypersensitivity to levothyroxine or excipients
- Untreated thyrotoxicosis
- Acute MI, especially if complicated by thyrotoxicosis
Adverse Reactions
- Palpitations
- Tachycardia
- Nervousness
- Headache
- Fatigue
- Menstrual irregularities
- Hair loss
- Weight loss
Drug Interactions
- Iron and calcium supplements: decrease absorption
- Warfarin: altered coagulation
- Theophylline: increased clearance
- Digoxin: increased effect
- Antidiabetic agents: altered glucose control
Curated Content: Needs Vetting Before Put to Clinical Use