It has all the pharmacologic activities of the natural substance. Thyroid hormones are believed to exert most of their actions through control of protein synthesis. At higher concentrations, they decrease protein synthesis, uncouple oxidative phosphorylation and increase the breakdown of glycogen, lipids and protein.
Liothyronine is readily available to body tissues.
The onset of activity of liothyronine is rapid, occurring within a few hours. Maximum pharmacologic response occurs within 2 or 3 days, providing early clinical response. The biological half-life is about 2.5 days. The drug has a rapid cut off of activity, which permits quick dosage adjustment and facilitates control of the effects of overdosage, should they occur. Liothyronine is metabolized to deiodinated and conjugated metabolites which are excreted in the urine.