Didier Concordet, Peggy Gandia, Jean-Louis Montastruc, Alain Bousquet-Mélou, Peter Lees, Aude Ferran, Pierre-Louis Toutain
In France, more than 2.5 million patients are currently treated with levothyroxine, mainly as the marketed product Levothyrox® . In March 2017, at the request of French authorities, a new formulation of Levothyrox® was licensed, with the objective of avoiding stability deficiencies of the old formulation. Before launching this new formulation, an average bioequivalence trial, based on European Union recommended guidelines, was performed. The implicit rationale was the assumption that the two products, being bioequivalent, would also be switchable, allowing substitution of the new for the old formulation, thus avoiding the need for individual calibration of the dosage regimen of thyroxine, using the thyroid-stimulating hormone level as the endpoint, as required for a new patient on initiating treatment...
July 2019: Clinical Pharmacokinetics