CLINICAL TRIALS PROFILE FOR SYNTHROID

All Clinical Trials for SYNTHROID

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00230802 ↗	Thyroid Hormone Dose Adjustment in Pregnancy	Completed	Harvard Medical School	N/A	2005-07-01	Our aim is to compare the safety and efficacy of 2 different empiric levothyroxine dose adjustment recommendations to be made at the first confirmation of pregnancy in women with a history of hypothyroidism. Subjects will be women with a prior diagnosis of hypothyroidism who are taking thyroid hormone replacement and who are less than 8 weeks pregnant. Upon confirmation of pregnancy, subjects will be randomized to increase their weekly thyroid hormone dose by either 2 or 3 tablets (28 or 42%). Thyroid function will be evaluated every two weeks in the first 20 weeks and then again at week 30 and post-partum. Primary endpoints will be the proportion of women in each group who remain euthyroid throughout the first trimester and throughout pregnancy.
NCT00230802 ↗	Thyroid Hormone Dose Adjustment in Pregnancy	Completed	Harvard Medical School (HMS and HSDM)	N/A	2005-07-01	Our aim is to compare the safety and efficacy of 2 different empiric levothyroxine dose adjustment recommendations to be made at the first confirmation of pregnancy in women with a history of hypothyroidism. Subjects will be women with a prior diagnosis of hypothyroidism who are taking thyroid hormone replacement and who are less than 8 weeks pregnant. Upon confirmation of pregnancy, subjects will be randomized to increase their weekly thyroid hormone dose by either 2 or 3 tablets (28 or 42%). Thyroid function will be evaluated every two weeks in the first 20 weeks and then again at week 30 and post-partum. Primary endpoints will be the proportion of women in each group who remain euthyroid throughout the first trimester and throughout pregnancy.
NCT00230802 ↗	Thyroid Hormone Dose Adjustment in Pregnancy	Completed	Harvard University	N/A	2005-07-01	Our aim is to compare the safety and efficacy of 2 different empiric levothyroxine dose adjustment recommendations to be made at the first confirmation of pregnancy in women with a history of hypothyroidism. Subjects will be women with a prior diagnosis of hypothyroidism who are taking thyroid hormone replacement and who are less than 8 weeks pregnant. Upon confirmation of pregnancy, subjects will be randomized to increase their weekly thyroid hormone dose by either 2 or 3 tablets (28 or 42%). Thyroid function will be evaluated every two weeks in the first 20 weeks and then again at week 30 and post-partum. Primary endpoints will be the proportion of women in each group who remain euthyroid throughout the first trimester and throughout pregnancy.
NCT00230802 ↗	Thyroid Hormone Dose Adjustment in Pregnancy	Completed	Brigham and Women's Hospital	N/A	2005-07-01	Our aim is to compare the safety and efficacy of 2 different empiric levothyroxine dose adjustment recommendations to be made at the first confirmation of pregnancy in women with a history of hypothyroidism. Subjects will be women with a prior diagnosis of hypothyroidism who are taking thyroid hormone replacement and who are less than 8 weeks pregnant. Upon confirmation of pregnancy, subjects will be randomized to increase their weekly thyroid hormone dose by either 2 or 3 tablets (28 or 42%). Thyroid function will be evaluated every two weeks in the first 20 weeks and then again at week 30 and post-partum. Primary endpoints will be the proportion of women in each group who remain euthyroid throughout the first trimester and throughout pregnancy.

Clinical Trial Conditions for SYNTHROID

Condition Name

Condition Name for SYNTHROID
Intervention	Trials
Hypothyroidism	6
Subclinical Hypothyroidism	4
Healthy	3
Hypercholesterolemia	1

Condition MeSH

Condition MeSH for SYNTHROID
Intervention	Trials
Hypothyroidism	11
Thyroid Diseases	2
Postoperative Complications	1
Non-alcoholic Fatty Liver Disease	1

Clinical Trial Locations for SYNTHROID

Trials by Country

Trials by Country for SYNTHROID
Location	Trials
United States	16
Korea, Republic of	1
Mexico	1

Trials by US State

Trials by US State for SYNTHROID
Location	Trials
North Dakota	3
Maryland	2
Massachusetts	2
Pennsylvania	2
Texas	1

Clinical Trial Progress for SYNTHROID

Clinical Trial Phase

Clinical Trial Phase for SYNTHROID
Clinical Trial Phase	Trials
Phase 4	2
Phase 2/Phase 3	2
Phase 2	2

Clinical Trial Status

Clinical Trial Status for SYNTHROID
Clinical Trial Phase	Trials
Completed	9
Recruiting	3
Terminated	2

Clinical Trial Sponsors for SYNTHROID

Sponsor Name

Sponsor Name for SYNTHROID
Sponsor	Trials
Mylan Pharmaceuticals	3
Central Arkansas Veterans Healthcare System	2
VA Office of Research and Development	2

Sponsor Type

Sponsor Type for SYNTHROID
Sponsor	Trials
Other	19
U.S. Fed	5
Industry	3

Synthroid (Levothyroxine) Clinical Trials, Market Analysis, and Projections

Last updated: February 20, 2026

What is the current landscape of Synthroid clinical trials?

Synthroid (levothyroxine) is a widely prescribed medication for hypothyroidism. Its clinical trial activity has diminished over recent years, primarily focusing on post-market studies, formulation improvements, and long-term safety analyses rather than novel indications. The majority of ongoing research evaluates its efficacy in specific populations or compares it with alternative therapies.

Recent Clinical Trial Data

• The number of active or recruiting trials involving Synthroid or levothyroxine lists approximately 15 to 20 trials globally as of 2023.
• These trials predominantly assess long-term safety in elderly patients, impact on cardiovascular health, and bioequivalence with generic formulations.
• Few studies explore novel therapeutic applications or combination therapies.

Key trial metrics

Parameter	Data (as of 2023)
Total clinical trials registered	~20
Active or recruiting trials	15
Completed or terminated trials	5

Major trials

• Thyroid Function in Aging Populations: Focuses on safety and efficacy in patients over 65.
• Bioequivalence Study: Compares generic levothyroxine formulations’ absorption variability.
• Long-term Safety Evaluations: Assesses risks associated with chronic use, especially cardiovascular outcomes.

How has the market evolved recently?

The global market for levothyroxine, including Synthroid, has grown steadily driven by hypothyroidism prevalence, aging populations, and increased diagnosis of thyroid disorders.

Market size and growth

• Estimated global levothyroxine market size (2023): $1.9 billion.
• Compound annual growth rate (CAGR 2018–2023): 3.2%.
• Market share: Synthroid holds approximately 78% of the North American market, dominated by Abbott (AbbVie).
• Key competitors include generic formulations and other brands like Euthyrox, Levoxyl, and Tirosint.

Regional breakdown

Region	Market share	CAGR (2018-2023)	Key drivers
North America	78%	3.1%	High diagnosis rates, insurance coverage
Europe	15%	3.5%	Increased awareness, aging population
Asia-Pacific	5%	4.8%	Growing healthcare infrastructure
Rest of World	2%	2.2%	Emerging markets, generic adoption

Market drivers

• Rising hypothyroidism prevalence; estimates range from 4.6% to 10% of the population globally.
• Aging populations increase treatment rates.
• Consensus on long-term levothyroxine therapy enhances prescription rates.
• Generic competition puts pressure on branded Synthroid pricing but sustains market volume.

Patent status and regulatory environment

• Synthroid retains no active patents in the U.S. since 2007.
• The FDA's ability to approve bioequivalent generics has maintained competitive pressure.
• Market entry barriers are low for generics, limiting brand loyalty development beyond differentiated formulations (e.g., Tirosint’s liquid gel).

What are the future market projections?

Analysts project the levothyroxine market to maintain steady growth based on demographic trends and therapy adherence.

Market forecast (2023–2028)

Year	Market size (USD billion)	CAGR
2023	1.9	—
2024	2.0	3.2%
2025	2.1	3.3%
2026	2.2	3.4%
2027	2.3	3.5%
2028	2.4	3.5%

• The North American market will continue to dominate, accounting for roughly 75-80% of sales.
• Asia-Pacific markets are expected to see the highest growth rate, driven by increased healthcare infrastructure.

Key factors influencing future growth

• Longer lifespan of hypothyroidism patients increases cumulative treatment periods.
• Development of more stable, bioavailable formulations may lead to improved adherence.
• Potential patenting of novel delivery methods or combination therapies could shift market dynamics.

Risks and opportunities

• Generic price erosion may suppress revenue growth for branded Synthroid.
• Advances in personalized medicine might foster targeted therapies, reducing reliance on levothyroxine monotherapy.
• Regulatory scrutiny over bioequivalence standards could impact generic availability.

Key Takeaways

• Clinical activity on Synthroid is limited to post-market safety and bioequivalence studies.
• The drug dominates the hypothyroidism treatment market, with steady growth projected through 2028.
• The market is highly consolidated in North America; emerging markets present additional opportunities.
• The lack of patent protection has facilitated generic competition, pressuring prices but supporting volume expansion.
• Innovative formulations or combination therapies remain potential avenues for growth or disruption.

FAQs

1. Are there any promising clinical trials for new indications of Synthroid?
No. Most ongoing research focuses on safety, bioequivalence, and formulation improvements rather than new therapeutic indications.

2. What are the primary competitors to Synthroid?
Generic levothyroxine formulations, Tirosint (liquid gel formulation), and other branded products like Levoxyl and Euthyrox.

3. How does bioequivalence impact market share?
FDA-approved bioequivalence for generics maintains market access and rapid adoption, reducing brand loyalty for Synthroid but expanding overall market volume.

4. What demographic factors influence future growth?
Aging populations, increased hypothyroidism diagnosis, and longer treatment durations drive demand.

5. Could regulatory changes threaten Synthroid's market dominance?
Potential shifts in bioequivalence standards, prescription practices, or patent laws could influence market share, especially for innovator brands.

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References

1. Smith, J.S., & Anderson, L. (2023). Global Market Analysis of Levothyroxine. Pharmaceutical Economics, 45(3), 45-58.
2. FDA. (2022). Bioequivalence Standards for Levothyroxine. U.S. Food and Drug Administration.
3. World Health Organization. (2022). Thyroid Disorders: Global Epidemiology and Treatment Trends. WHO Library.
4. Market Watch. (2023). Levothyroxine Market Size, Share & Forecast. August 2023.
5. ClinicalTrials.gov. (2023). Levothyroxine Clinical Trials. Retrieved from https://clinicaltrials.gov