The Dutch Ministry of Health, Welfare and Sport (VWS) requested the Netherlands Organisation for Health Research and Development (ZonMw) to finance a study on the effect of switching from Thyrax Duotab to other brands of levothyroxine after a stock-out of Thyrax Duotab in the Netherlands. The stock-out was the result of a temporary interruption of the production and forced thousands of Thyrax Duotab users to switch to other brands of levothyroxine.

The Dutch Society for Endocrinology (NVE) and the Dutch Thyroid Organisation (SON) initiated the study and it will be performed by the PHARMO Institute and the Netherlands Institute for Health Services Research (NIVEL). The Netherlands Pharmacovigilance Centre Lareb, the Medicines Evaluation Board and the Dutch College of General Practitioners (NHG) are involved in the development and interpretation of the study. The study comprises of two parts: one into the effect of switching on blood levels of thyroid hormone and one part focusing on patient experiences after switching. The results of the study will guide healthcare providers in advising patients before switching and monitoring of patients during/after switching.

The study will be finalised end 2016, but interim results are expected in within a few months. For more information, questions or comments, please contact the research team at

For the official press statement (in Dutch) by the Dutch Thyroid Organisation, click here.

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