A synthetic, converted form of the natural thyroid hormone triiodothyronine (T3) originating from T4, liothyronine is not intended for use as sole maintenance therapy. However, it can be used together with levothyroxine in small doses (5-15 µg/d), when levothyroxine therapy is unsuccessful. The recommended ratio of T4 to T3 is 10-14:1. T3 has a short duration of activity (half-life, 12-24 hours), which allows quick dosage adjustments in the event of overdosage.
In theory, liothyronine may be preferable for patients with impaired gastrointestinal absorption in that 95% of liothyronine is absorbed, compared with 50-80% of T4. Dosage recommendations are for short-term use under the guidance of an endocrinologist in special circumstances, such as myxedema coma.
Learn more about liothyronine (liothyronine).
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Cite this: Mary L. Windle. Rapid Rx Quiz: Thyroid Drugs - Medscape - Jul 20, 2022.