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Levothyroxine
From WikEM
Contents
Administration
- Type: Endocrine
- Dosage Forms:
- Routes of Administration: PO, IV
- Common Trade Names: Synthroid
Adult Dosing
- Myxedema coma: 300-500 mcg IV x1, then 50-100mcg IV daily until able to tolerate PO
- Hypothyroidism: doses vary
Pediatric Dosing
- Hypothyroid: Doses vary, 1.7-15 mcg/kg/day PO
Special Populations
- Pregnancy Rating: A
- Lactation risk: Infant risk minimal
- Renal dosing: Not defined
- Hepatic dosing: Not defined
Contraindications
- Allergy to class/drug, hypersensitivity to glycerol
- Uncorrected adrenal insufficiency (may precipitate acute adrenal crisis)
- Acute MI
- Subclinical or overt thyrotoxicosis, nontoxic diffuse goiter, nodular thyroid disease
Adverse Reactions
Serious
- MI, heart failure, tachycardia, cardiac arrest
- Pseudotumor, seizure
- Dyspnea
- Hyperthyroid
- Decreased bone mineral density, hip fracture
Common
- Palpitations
- Diarrhea
- Anxiety, insomnia, fatigue, sweating, weight loss
- Alopecia
Pharmacology
- Half-life: 6-7 days
- Metabolism: Hepatic
- Excretion: Renal, fecal
Mechanism of Action
- Synthetic thyroid hormone (T4)
