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Feature Pharmacovigilance

Risks of reformulation: French patients complain after Merck modifies levothyroxine pills

BMJ 2018; 360 doi: (Published 16 February 2018) Cite this as: BMJ 2018;360:k714
  1. Barbara Casassus, freelance journalist
  1. Paris, France
  1. barbara.casassus{at}

Huge rises in side effects have led to protests and legal charges, reports Barbara Casassus

Thousands of patients in France have complained about adverse effects after taking a modified version of Merck’s Lévothyrox (levothyroxine).

Since the drug was reformulated last year, patients have reported problems including fatigue, memory loss, palpitations, weight gain, dizziness, and nausea, prompting 318 077 signatories to a petition demanding Merck return to the previous formulation.1

The concerns of patients have led to an emergency parliamentary inquiry and the initiation of a criminal investigation by the public prosecutor for Marseilles, while the French health minister has asked Merck to continue providing the old formulation temporarily.

Meanwhile several groups of patients are taking legal action.

“Merck intends to continue to cooperate fully . . . and will provide the investigating judges . . . with all necessary documents and information,” its spokesman Matthias Reinig told The BMJ.

The European Medicines Agency is unfazed by recent events, however. It said that the pattern of side effects is the same for both Lévothyrox versions, and that “particularly high media attention and strengthened surveillance” may have increased reporting of side effects.

Lawsuits over levothyroxine

The lawyer Marie-Odile Bertella-Geffroy has filed criminal charges, among them for endangering lives, on behalf of 1200 patients, including members of the French Association of Thyroid Patients (AFMT), some of whom say they are buying the old formulation from abroad.

Another association, Vivre sans thyroîde (Living without a thyroid), has asked the law firm MySMARTCab to file a civil claim, which will be heard in Lyon on 1 October. It wants full information about the reasons for the switch and the composition of the new version.

MySMARTCab says that it intends to file another …

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