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Open Access 01-07-2019 | Levothyroxine | Letter to the Editor

Authors’ Reply to Nicolas: “Levothyrox^® New and Old Formulations: Are they Switchable for Millions of Patients?”

Authors: Didier Concordet, Peggy Gandia, Jean-Louis Montastruc, Alain Bousquet-Mélou, Peter Lees, Aude A. Ferran, Pierre-Louis Toutain

Published in: Clinical Pharmacokinetics | Issue 7/2019

Excerpt

We thank Dr. Nicolas for his detailed comments on our article [1]. These we refute from both general and particular perspectives. This response to Dr. Nicholas explains why we do not accept the premises of his reasoning and the deductions he derives, as they lead, in consequence and ineluctably to his wrong conclusions. We reiterate the point made firmly in our article that: when all patients in a population (almost 3 million persons in France in 2017) had been treated with the same licensed Levothyrox^® formulation; and when this was administratively and irreversibly switched to a new Levothyrox^® formulation, the conclusion must be that this is a switchability issue. Moreover, as we also made previously clear, switchability cannot be established by a classical average bioequivalence (ABE) trial, especially not for a drug like levothyroxine, which has a narrow therapeutic index (NTI). …

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Title: Authors’ Reply to Nicolas: “Levothyrox® New and Old Formulations: Are they Switchable for Millions of Patients?”
Authors: Didier Concordet
Peggy Gandia
Jean-Louis Montastruc
Alain Bousquet-Mélou
Peter Lees
Aude A. Ferran
Pierre-Louis Toutain
Publication date: 01-07-2019
Publisher: Springer International Publishing
Keyword: Levothyroxine
Published in: Clinical Pharmacokinetics / Issue 7/2019
Print ISSN: 0312-5963
Electronic ISSN: 1179-1926
DOI: https://doi.org/10.1007/s40262-019-00781-1

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Authors’ Reply to Nicolas: “Levothyrox^® New and Old Formulations: Are they Switchable for Millions of Patients?”

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