French police visit Merck KGaA Lyon plant as part of levothyrox probe

By Gareth Macdonald

- Last updated on GMT

French police visit Merck KGaA Lyon plant as part of levothyrox probe

Related tags Pharmacology

Police investigating thousands of adverse events linked to Levothyrox, a reformulated version of the hypothyroidism pill Euthyrox, have visited Merck KGaA's production facility in Lyon, France.

The German drug manufacturer told us officers from the Central Office of Public Health of the National Gendarmerie of France (OCLAESP) visited the site last night in response to an investigation by French authorities.

It said: “As part of the preliminary investigation opened by the Marseille Public Prosecutor’s Office on the new formulation of levothyrox, the investigators went yesterday, 3 October 2017, to Lyon at the premises of the Merck headquarters in France.

The firm added that it “will cooperate fully to support the work of the investigators of the OCLAESP and to provide them with all requested information which may be useful for their work.


The raid comes just weeks after the reformulated drug – which contains the excipient mannitol rather than lactose – was linked to a surge in adverse event reports in France.

In September, ANSM told us that between August 16 and September 9 it received 9,000 adverse event reports related to Levothyrox (​levothyroxine)

Despite this, the agency – whose 2012 request for tightened potency specifications for levothyroxine products prompted Merck to reformulate – said the drug’s efficacy and safety profile had not changed.

It pointed out that “The active substance of the novel formula is unchanged in its nature and in its dosage​” adding that "The new formula ensures a stable quantity of active substance which is more constant from one lot to another or within the same batch and throughout the shelf life of the product than the old formulation. The quality of the drug has therefore been improved.

This was echoed by both Merck and French health minister Agnes Buzyn, who told the press​ (in French) the problem was how information about the new formulation had been communicated.

Buzyn said: "There is no fraud, there is no conspiracy, there is no error, there was a problem of informing the patients (...) and therefore the patients were found surprised by a formulation that had changed and that for some gave side effects​” according to Le Figaro.

"Many of these side effects are related to difficulties in correctly re-ordering Levothyrox but they fade when the treatment is well dosed​" she said.


In the weeks since, Merck has relaunched the original Euthyrox formulation

The firm told us “as of June, some patients experiencing persistent side effects launched an online petition to go back on the previous formulation. This situation received a very significant amount of public attention and media coverage.

The French Minister of Health addressed these patients concerns on September 15th by asking Merck to reintroduce the previous formulation within 15 days, on a temporary basis and under medical prescription only for patients with persistent and undesirable side effects​.” 

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