In Vivo Comparison of Levothyroxine Preparations

Abstract

Two brands of levothyroxine sodium (Levothroid and Synthroid) were found not to be bioequivalents. Until a more precise standardization for levothyroxine sodium preparation is available, patients should be consistently treated with one brand name preparation. Adjustment of the dosage may be necessary if the treatment is switched from one brand name preparation to another. (<i>JAMA</i>1982;247:203-205)