levothyroxine(Synthroid, Levoxyl, Unithroid)
Synthetic thyroid hormone (T4)
Pronunciation
/ˌliːvoʊθaɪˈrɒksiːn/ Mechanism of action Synthetic L-isomer of thyroxine (T4), a thyroid hormone. After absorption, T4 is converted peripherally to the more active T3 by deiodinases. T3 binds nuclear thyroid hormone receptors, modulating transcription of genes that regulate basal metabolic rate, growth, development, and cardiac, neurologic, and metabolic function. Replaces deficient endogenous thyroid hormone in hypothyroidism \\[1\\]. Standard dosing -/
International Phonetic Alphabet (IPA). Say it aloud once — you will remember it forever.
At a glance
- Generic name
- levothyroxine
- Brand names
- Synthroid, Levoxyl, Unithroid, Tirosint (gelcap/solution), Euthyrox
- Therapeutic class
- Synthetic thyroid hormone (T4)
- Mechanism (summary)
- Synthetic L-isomer of thyroxine (T4), a thyroid hormone. After absorption, T4 is converted peripherally to the more active T3 by deiodinases. T3 binds nuclear thyroid hormone receptors, modulating transcription of genes that regulate basal metabolic rate, growth, development, ...
Clinical pearls
- Take ONCE DAILY ON AN EMPTY STOMACH, ideally 30--60 minutes before
- breakfast, with a full glass of water. An alternative is at bedtime,
- at least 3--4 hours after the last meal.
- Wait at least 4 hours before taking calcium, iron, multivitamins
- with minerals, antacids, sucralfate, or cholesterol-binding resins.
Sources
See how levothyroxine appears in NAPLEX-style questions
PharmDHub Premium includes a full drug card, dosing, boxed warnings, drug-drug interactions, and practice questions built around this drug.