section name header

Indications

REMS


Contraind./Precautions

Contraindicated in:

Use Cautiously in:

Adv. Reactions/Side Effects

Usually only seen when excessive doses cause iatrogenic hyperthyroidism

CV: angina, arrhythmias, tachycardia

Derm: sweating

Endo: heat intolerance, hyperthyroidism, menstrual irregularities

GI: abdominal cramps, diarrhea, vomiting

Metab: weight loss

MS: accelerated bone maturation in children

Neuro: headache, insomnia, irritability

Interactions

Drug-drug:

Drug-Food:

Availability

(Generic available)

Route/Dosage

US Brand Names

Ermeza, Euthyrox, Levo-T, Levoxyl, Synthroid, Thyquidity, Tirosint, Tirosint-SOL, Unithroid

Action

  • Synthetic form of thyroxine (T4). Replacement of or supplementation to endogenous thyroid hormones.
  • Principal effect is increasing metabolic rate of body tissues:
    • Promote gluconeogenesis,
    • Increase utilization and mobilization of glycogen stores,
    • Stimulate protein synthesis,
    • Promote cell growth and differentiation,
    • Aid in the development of the brain and CNS.
Therapeutic effects:
  • Replacement in hypothyroidism to restore normal hormonal balance.
  • Suppression of thyroid cancer.

Classifications

Therapeutic Classification: hormones

Pharmacologic Classification: thyroid preparations

Pharmacokinetics

Absorption: Levothyroxine is variably (40–80%) absorbed from the GI tract.

Distribution: Distributed into most body tissues.

Protein Binding: >99%.

Metabolism/Excretion: Metabolized by the liver and other tissues to active T3. Thyroid hormone undergoes enterohepatic recirculation and is excreted in the feces via the bile.

Half-Life: 6–7 days.

Canadian Brand Names

Eltroxin

Time/Action Profile

ROUTEONSETPEAKDURATION
POunknown1–3 wk1–3 wk
IV6–8 hr24 hrunknown



Patient/Family Teaching

Pronunciation

lee-voe-thye-ROX-een

Pill Image

Levothyroxine_195-8801.jpg
Levothyroxine_195-8812.jpg
Levothyroxine_195-9153.jpg
Levothyroxine_195-9231.jpg