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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Brand name levothyroxine (Synthroid) | Experimental | Dose previously demonstrated to normalize thyroid function given daily for 2 months |
|
| Generic formulation of Levothyroxine | Active Comparator | Dosage previously determined to normalize thyroid function given daily for 2 months |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Brand Name Levothyroxine (Synthroid) | Drug | 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. |
| Measure | Description | Time Frame |
|---|---|---|
| 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. | 3 points over 16 weeks |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Rosalind S Brown, MD | Boston Children's Hospital | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Children's Hospital Boston | Boston | Massachusetts | 02115 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 23264396 | Result | 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. |
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Nothing currently planned
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Subjects' ages had to be between 3-18 years and had a diagnosis of hypothyroidism, either congenital or acquired with an initial TSH of >100 uIU/mL.
Subjects were recruited through flyers in the endocrine clinic and letters with opt-out cards to contact. Recruitment started November 2006 and completed ended March 2010.
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| ID | Title | Description |
|---|---|---|
| FG000 | Group 1 | Branded Synthroid 8 weeks, then generic levothyroxine 8 weeks |
| FG001 | Group 2 | Generic levothyroxine for 8 weeks then branded Synthroid for 8 weeks |
| Title | Milestones | Reasons Not Completed | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
|
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| ID | Title | Description |
|---|---|---|
| BG000 | Group 1 | Branded Synthroid 8 weeks, then generic levothyroxine 8 weeks |
| BG001 | Group 2 | Generic levothyroxine 8 weeks, then branded Synthroid 8 weeks |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Categorical | Count of Participants |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | 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. | Posted | Mean | Standard Error | uIU/mL | 3 points over 16 weeks |
|
|
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Group 1 | Crossover; Branded Synthroid 8 weeks, then generic levothyroxine 8 weeks |
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Proof of principle study; small sample. Results may not be applicable to all populations.
| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Jeremi Carswell, MD | Children's Hospital Boston | 617-355-7476 | Jeremi.Carswell@childrens.harvard.edu |
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| ID | Term |
|---|---|
| D003409 | Congenital Hypothyroidism |
| D007037 | Hypothyroidism |
| ID | Term |
|---|---|
| D004392 | Dwarfism |
| D001848 | Bone Diseases, Developmental |
| D001847 | Bone Diseases |
| D009140 | Musculoskeletal Diseases |
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| ID | Term |
|---|---|
| D013974 | Thyroxine |
| ID | Term |
|---|---|
| D013963 | Thyroid Hormones |
| D006728 | Hormones |
| D006730 | Hormones, Hormone Substitutes, and Hormone Antagonists |
| D024322 | Amino Acids, Aromatic |
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|
|
| Generic formulation of Levothyroxine | Drug | 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. |
|
|
| non-compliant |
|
| BG002 | Total | Total of all reporting groups |
| Participants |
|
| Age, Continuous | Mean | Standard Deviation | years |
|
| Sex: Female, Male | Count of Participants | Participants |
|
| Region of Enrollment | Number | participants |
|
|
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| 0 |
| 13 |
| 0 |
| 13 |
| 0 |
| 13 |
| EG001 | Group 2 | Crossover; Generic levothyroxine 8 weeks, then Branded Synthroid 8 weeks, then generic | 0 | 18 | 0 | 18 | 0 | 18 |
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| D001849 |
| Bone Diseases, Endocrine |
| D030342 | Genetic Diseases, Inborn |
| D009358 | Congenital, Hereditary, and Neonatal Diseases and Abnormalities |
| D004700 | Endocrine System Diseases |
| D013959 | Thyroid Diseases |
| D000598 | Amino Acids, Cyclic |
| D000596 | Amino Acids |
| D000602 | Amino Acids, Peptides, and Proteins |