EFFECT OF CLOFIBRATE ON SERUM THYROXINE TRANSPORT AND FREE THYROXINE LEVELS

Alterations in thyroxine transport have been implicated as a factor in the mechanism of action of Clofibrate (Atromid-S), an agent that has been shown to lower serum cholesterol and triglycerides in many species including man. Acute and prolonged effects of Clofibrate on peripheral thyroid indices (thyroxine binding to serum protein carriers, free thyroxine levels, and resin uptake of thyroxine and triiodothyronine) were investigated in 12 subjects. In the acute studies over an 8 hour period after Clofibrate administration, the endogenous distribution of thyroxine to thyroxine binding prealbumin (TBPA) decreased significantly, but free thyroxine levels remained unchanged; the changes in TBPA binding were, however, not significantly different from binding levels without the drug over this period. In the prolonged studies, no significant changes in peripheral thyroid indices were found following 4 weeks of drug administration. The studies presented do not support the concept that alterations in serum thyroxine transport are related to the action of Clofibrate in man. © 1969.