Thyroid Experts Speak Out Against the FDA’s Decision to Approve Generic Levothyroxine Preparations
FDA approval of generic levothyroxine preparations as equivalent to branded products is major concern of thyroid experts
June 28, 2004
(FALLS CHURCH, VA)—Three organizations whose members specialize in the treatment of endocrine disorders recently voiced concern and dismay at the Food and Drug Administration’s (FDA) decision to approve generic substitutes for levothyroxine products, which are used to treat hypothyroidism, or an underactive thyroid, without input from clinical endocrinologists, the recognized experts who care for thyroid patients.
These generic drugs are now judged to have the same clinical effect and safety profile as the branded product, allowing a pharmacist to substitute one drug for the other without physician approval. In a June 24, 2004, statement, the American Thyroid Association (ATA), The Endocrine Society (TES), and the American Association of Clinical Endocrinologists (AACE) outlined their concerns for the health of the millions of Americans using levothyroxine products while alerting physicians about this change to prepare them to advise their thyroid patients.
The organizations explain that the FDA had previously indicated that it would seek input from clinical endocrinologists and would carefully consider standards of thyroxine bioequivalence and testing before making such a decision.
“Our organizations established a dialogue with the FDA over the past year about this matter and other issues of assessing levothyroxine therapy,” says Gregory Brent, MD, ATA Secretary, “only to have the FDA make this decision without our input. The goal of the more than 4,600 clinical endocrinologist members of our groups continues to be the development of a responsible and scientifically informed approach to levothyroxine therapeutic substitution for the 13 million Americans who take these products,” adds Dr. Brent. “The FDA’s recent actions will result in patients being switched among a number of levothyroxine preparations, often without their or their doctors’ knowledge, with the possibility of an increase in adverse events.”
Levothyroxine is a drug recognized to have a narrow toxic to therapeutic ratio with significant clinical consequences of excessive or inadequate treatment, says the statement. Some of the potential adverse events include the recurrence of symptoms, osteoporosis, atrial fibrillation, worsening of ischemic heart disease, preterm delivery in pregnancy, and high cholesterol.
The statement goes on to warn that those especially susceptible to incorrect titration of levothyroxine products include the elderly, pregnant women and their developing fetuses, and those with thyroid cancer.
The current recommendation by the FDA and these organizations is that patients switching between branded levothyroxine products have repeat thyroid function testing, which will allow for dose retitration if the therapeutic target is not being achieved with the new preparation. “Under a policy of allowing generic levothyroxine substitution,” the statement concludes, “more frequent thyroid function testing will be necessary.” Furthermore, the statement cautions, the patient and doctor may not be aware of a change in preparation before adverse events occur.
As a result of the FDA decision, the ATA, TES, and AACE advise physicians caring for patients on levothyroxine therapy to —
1. Alert their patients that their levothyroxine preparation may be switched at the pharmacy,
2. Encourage their patients to ask to remain on their current levothyroxine preparation, and
3. Make sure their patients understand that if they receive a new levothyroxine preparation that they will need to be retested with a serum TSH to determine if they need dose retitration.
The statement can be found on the ATA’s web site
Founded in 1923, the ATA is a professional society of 900 U.S. and international physicians and scientists who specialize in the research and treatment of thyroid diseases. The Association is dedicated to promoting scientific and public understanding of the biology of the thyroid gland and its disorders, so as to improve methods for their revention, diagnosis, and management. The ATA fosters excellence in research, patient care, and education of patients, the public, and the medical and scientific communities while guiding public policy about the prevention and management of thyroid diseases.
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