Synthroid (levothyroxine) Dosage Guide
LEVOTHYROXINE (lee-voe-thye-rox-een) Levo-T, Levothroid, Levoxyl, Synthroid hormone (thyroid preparation) Pregnancy Category A
INDICATIONS: Diminished or absent thyroid function.
Therapeutic Effects: Restoration of normal hormonal balance.
-
DOSAGE Guide:
PO: Adults: 75–125 ug/d (1.5 ug/kg/d).
Geriatric Patients: 75 ug/d. Children > 10 yr: 150–200 ug/d (2–3 ug/kg/d).
Children 6–10 yr: 100–150 ug/d (4–5 ug/kg/d.)
Children 1–5 yr: 75–100 ug/d (3–5 ug/kg/d).
Children 6–12 mo: 50–75 ug/d (5–6 ug/kg/d).
IM, IV: Adults: Hypothyroidism: 50–100 ug/d. Myxedema coma/stupor: 200–500 ug IV.
Children:Hypothyroidism: 75% of the calculated oral dose.
- ADMINISTRATION: PO:
Administer as a single dose, before breakfast. Direct IV: Dilute with 0.9% NaCl without preservatives, for a concentration of 100 ug/mL. Rate: 100 ug over 1 min.
- ADVERSE REACTIONS AND SIDE EFFECTS:
Insomnia, irritability, nervousness, CARDIOVASCULAR COLLAPSE, arrhythmias, tachycardia, angina pectoris, hypertension, diarrhea, vomiting, hair loss (in children), increased sweating, hyperthyroidism, menstrual irregularities, weight loss, heat intolerance, accelerated bone maturation in children.
-
CONTRAINDICATIONS:
Hypersensitivity, recent MI, thyrotoxicosis.
-
CAUTIONS:
Bile acid sequestrants decrease absorption of orally administered thyroid preparations.
- May alter the effectiveness of warfarin.
- May cause an increase in the requirement for insulin or oral hypoglycemic agents in diabetics.
- Concurrent estrogen therapy may increase thyroid replacement requirements.
- Additive cardiovascular effects with adrenergics (sympathomimetics).
- May decrease response to beta-blockers.
- Dose should be withheld and health care professional notified if resting pulse >100 bpm.
