Generic vs. Name-Brand Levothyroxine

Generic vs. Name-Brand Levothyroxine: Assessment of Bioequivalence Using TSH as a Marker in Children With Permanent Hypothyroidism

This study compares two different brands of thyroxine (thyroid hormone). Currently, pharmacists may be substituting generic formulations of thyroid hormone without your doctor knowing about this. Although a small difference in thyroid function is not significant in most healthy children, adolescents and adults, in infants and toddlers even a small difference in thyroid function can have important harmful consequences on brain development. The purpose of the present study is to learn whether the difference between brands of thyroid hormone that are currently being substituted is sufficient to cause a difference in thyroid function.

This study is an unblinded, randomized controlled cross-over study, which involves taking 2 different forms of levothyroxine sequentially over a 16 week period. Subjects will have a total of 3 visits over this time period. At the first visit, subjects are randomized to receive either generic (Sandoz) levothyroxine or Synthroid (Abbott) brand of levothyroxine. Blood is drawn for baseline thyroid function studies and other markers which are influenced by thyroid hormone at each visit. The second visit is the cross-over visit, and the final visit is a close-out visit, after which each subject will resume taking their previous formulation of levothyroxine.

Randomized crossover study using 8 weeks of brand name levothyroxine (Synthroid, manufactured by Abbott), then 8 weeks of the generic formulation of levothyroxine (manufactured by Sandoz). The dose of medication does not change throughout the duration of the study.

Randomized crossover study using 8 weeks of the generic formulation of levothyroxine (manufactured by Abbott, then 8 weeks of brand name levothyroxine (Synthroid, manufactured by Abbott). The dose of medication does not change throughout the duration of the study.

Thyroid Stimulating Hormone as Primary Endpoint Measured at Initiation of Study, After 8 Weeks of One Drug, and Then 8 Weeks After the Second Drug.

Inclusion Criteria: Age between 3 and 18 years Diagnosis of Congenital Hypothyroidism with initial TSH > 100 Ability to understand directions and follow all instructions Exclusion Criteria: Not on any drug interfering with absorption of levothyroxine

Carswell JM, Gordon JH, Popovsky E, Hale A, Brown RS. Generic and brand-name L-thyroxine are not bioequivalent for children with severe congenital hypothyroidism. J Clin Endocrinol Metab. 2013 Feb;98(2):610-7. doi: 10.1210/jc.2012-3125. Epub 2012 Dec 21.