FDA may take regulatory action against Synthroid
Natural alternatives are available
The U.S. Food and Drug Administration (FDA) has told Abbott Laboratories of Abbott Park, IL that its thyroid drug Synthroid may be taken off the market after years of regulatory disputes, but a Florida physician is reminding health care practitioners that if this should happen, there is a safe, effective alternative that comes from natural sources.
"Armour Thyroid, taken from bovine and porcine thyroids, has been around for 50 years. I have used it in thousands of patients without incident in my 40 years of practice," says Sanford Siegel, MD, DO, a Miami physician. In fact, Siegel says, Armour Thyroid may be superior to synthetic thyroid hormones because research has shown patients who have taken the natural version have clear improvements in neuropsychological function, cognition, and mood.1,2
Some are unfamiliar with older treatments
Extracts of animal thyroid tissue, first used in 1892, contain both thyroxine and triiodothyronine and were the only available treatment for hypothyroidism for 50 years. Because of concern about their variable potency, animal-based thyroid extracts have fallen into disuse since synthetic thyroid hormones became available.
"Younger doctors haven’t even heard of natural thyroid," Siegel says. "Yet, there are thousands of patients who swear they do far better on the natural hormone than on the synthetic. There is no need for anyone to panic. If Synthroid becomes unavailable, the patient can easily be switched to natural thyroid, and in my opinion, they will respond even better."
The FDA’s concerns about Synthroid, which has been in use for 42 years and is the third most frequently prescribed drug in the United States, raise the possibility that regulatory action could be taken against the manufacturers of the drug as early as mid-August. Eight million Americans use Synthroid (levothyroxine), but it has never been subjected to the FDA testing and approval process.
FDA asking for new drug application
The FDA said four years ago that makers of thyroid medications like Synthroid needed to get FDA approval to continue marketing them. Abbott Laboratories, which acquired Synthroid manufacturer, BASF Pharma/Knoll in March, was informed by the FDA in April that it must file its own petitions to give Synthroid the generally recognized as safe and effective designation.
For its part, Abbott Laboratories says it intends to submit a new drug application to the FDA. "Like other drugs that were marketed before 1962, Synthroid and all other levothyroxine sodium products did not receive formal approval from the FDA. . . . In 1997, Knoll, the manufacturer of Synthroid at the time, filed a citizen petition requesting that FDA acknowledge that Synthroid be given a legal designation generally recognized as safe and effective,’" the company said in a written statement in early June. The statement says Abbott intends to submit similar applications.
"The safety and efficacy of Synthroid has been extensively studied and validated. . . . The place of Synthroid in clinical practice is well-established as a trusted therapy by physicians," the Abbott statement continues.
Albuquerque, NM, endocrinologist John Seibel, MD, FACP, MACE, says he prefers synthetic thyroid because it is 100% T4 hormones, compared to Armour thyroid, which is composed of T3 and T4. "T3 has a half-life of seven hours, and T4 has a half-life of seven days. Since you never know exactly how much T4 you are getting, it could cause a problem, especially in patients with angina. To be sure, patients on Armour Thyroid should take half their dosage in the morning and half at night," says Seibel.
References
1. Bunevicius R, et al. Effects of thyroxine as compared with thyroxine plus triidothyronine in patients with hypothyroidism. N Engl J Med 1999; 340:424-429.
2. Bunevicius R, Prange AJ. Mental improvement after replacement therapy with thyroxine plus triiodothyronine: Relationship to cause of hypothyrdoisim. Int J Neruopsycho-pharmacol 2000; 3:167-174.
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