The purpose of this study is to demonstrate bioequivalence (BE) between Euthyrox® tablets manufactured at Merck Nantong (Test Euthyrox) versus the tablets manufactured at Merck Darmstadt (Reference Euthyrox).

Inclusion Criteria:

• Participants have a body weight within 45 to 75 kilogram (kg) for females and 55 to 85 kg for males and Body mass index (BMI) within the range 19.0 to 26.0 kilograms per meter square (kg/m^2)
• Non-smoker for at least 3 months
• Contraceptive use by males or females will be consistent with any local regulations on contraception methods for those participating in clinical studies
• Capable of giving signed informed consent
• Total and free Thyroxine (T4), total and free Triiodothyronine (T3) and Thyroid-stimulating Hormone (TSH) must be within normal ranges at Screening
• Ability to understand the purposes and risks of the study
• Other protocol defined inclusion criteria could apply

Exclusion Criteria:

• Participants with history or presence of tumors of the pituitary gland or hypothalamus, thyroid or adrenal gland dysfunction or cardiac disease
• Participants with a concurrent medical condition known to interfere with the absorption or metabolism of thyroid hormones
• History or presence of relevant liver diseases or hepatic dysfunction. Participants with gall bladder removal
• Participants taking medications known to affect thyroid hormone metabolism, for example, oral contraceptives, hormonal implants, parenteral hormones, anabolic steroids, androgens, etcetera
• Use of any investigational device within 60 days prior to first dose administration
• Pregnant or breastfeeding a child
• Participant has smoked within the 3 months prior to Screening
• High fiber consumption within 24 hours before dosing in each period
• Participants with positive results from serology examination for Syphilis, Hepatitis B surface antigen, Hepatitis C Virus or Human Immunodeficiency Virus
• Participants with any clinically relevant abnormality in the safety laboratory parameters
• Participants with positive test for drugs of abuse (including alcohol) at Screening and on Day -1 of each period (urine)
• Other protocol defined exclusion criteria could apply

We are committed to enhancing public health through responsible sharing of clinical trial data. Following approval of a new product or a new indication for an approved product in both the US and the European Union, the study sponsor and/or its affiliated companies will share study protocols, anonymized patient data and study level data, and redacted clinical study reports with qualified scientific and medical researchers, upon request, as necessary for conducting legitimate research. Further information on how to request data can be found on our website bit.ly/IPD21