The levothyroxine spectrum: Bioequivalence and cost considerations
August 1, 2005
Levothyroxine, a critical medication for millions of Americans, has had a long and turbulent history. In the face of tougher FDA regulations and especially its reclassification as a "new drug" in 1997, manufacturers have struggled to carve out their niche in an expansive market. The principal concern of physicians, patients, endocrinologists, manufacturers, and FDA is levothyroxine's relative bioequivalence. Even after FDA classified several products as bioequivalent, a single brand name product still holds most of the market share, despite the fact that it is more costly. Current issues surrounding levothyroxine include: controversy about research, the number and types of recalls, the lack of a single reference-listed drug for comparison, and conflicting claims about the bioequivalence of various formulations. (Formulary. 2005;40:258–271.)