Generic vs. Brand Name Thyroid Medication -
Does it Matter?
There are many versions of Levothyroxine including generic and brand name formulations. The equivalence of these generic and brand name formulas are controversial. Many studies that have been done on the subject matter have been criticized. In fact, during the 1980s and 1990s many generic Levothyroxine tablets were recalled due to improper preparations. The American Thyroid Association, The Endocrine Society, and the American Association of Clinical Endocrinology, studied the adverse effects of thyroid medication are attributed to changes in TSH levels after patients are switched from name brand to generic formulas. In addition, many states have different regulations concerning interchanging generic and brand name medications. Most physicians agree on the importance of remaining on the same medication. However, pharmacists can prescribe generic forms at their discretion. These changes can result in bad effects on both adults and children.
Levothyroxine (L-thyroxine or LT4) is the conventional and most used thyroid medication to treat hypothyroidism. It comes in different strengths and different names. The most popular are Synthroid, Levoxyl, and Tirosint. Some product names are brand names, and others are generic ones. Brand and generic levothyroxine products may have very different contents of the active thyroid hormone even though the label indicates the same strength. Before Levothyroxine products became regulated by the Food and Drug Administration, the contents of L-thyroxine in the two main brand names were considered to be equivalent based on some research studies, although this equivalency was contested by many doctors.
In 1997, the new regulations set by the FDA required that all existing and new Levothyroxine products are approved through a drug application. However, the criteria of equivalency between products set by the FDA are not strict enough and allow for too much variation and differences between products. There is concern that a difference by as much as 12.5% of content of Levothyroxine among product names allowed by the FDA can result in treatment problems including overdose or under medication. As you can see, this opens the door to a clear misinformation concerning interchangeability and equivalency of different thyroid medication products. For instance, when Synthroid and a generic version of Levothyroxine were compared, the generic version was found to be 12.5% more potent than Synthroid, even though the two products were accepted by FDA criteria to be equivalent and interchangeable. Thyroid specialists are very concerned about this issue because when new formulations are released for the public, the FDA does not necessarily reassess the older version to establish uniformity among different products.
In a review conducted by Harvard University doctors, 31 severely hypothyroid children were given different Levothyroxine products. Half were given name brands and half were given generic forms of Levothyroxine. After a period of 8 weeks, the patients who took the generic form of Levothyroxine had significantly lower TSH levels, indicating overdose with thyroid hormone then those who took Synthroid. Such a significant difference is thought to be caused by reformulation. If you are treated with Levothyroxine, it is better to choose a brand name rather than a generic one and stick to the same product name to avoid treatment induced thyroid imbalance.
There has been considerable improvement in the quality of Levothyroxine products since the FDA regulations were implemented. Nevertheless, you need to be aware that thyroid hormone preparations can be switched by your pharmacy. Make sure you remain on the same medication at every refill. For this, you definitely need to be proactive and you also need to be retested every time the dose of Levothyroxine has been changed by your doctor.
Hypothyroidism is most commonly found in adults; however, when it affects children it can be especially damaging because of the impact thyroid hormone has on growth and development. Pregnant women with mild hypothyroidism, and not perfectly well-balanced with the right dose of medicine, can bring birth to babies with motor and brain development issues.
Children have much less of a thyroid hormone reserve in their bodies, and therefore are sensitive to the differences between brand name and generic thyroid hormone medication. In children with congenital hypothyroidism, there is worry that generic Levothyroxine has lower concentrations of T4 than brand names, which can lead to slower growth and also to mental development issues. A study published in the Journal for Clinical Endocrinology compared two forms of Levothyroxine medication and did not find a significant difference in the TSH of children who took generic and brand name forms of the drug. Due to the many concerns over the FDA’s protocol for determining equivalence, effectiveness of the generic form is still under speculation. However, when your child’s well-being is on the line it is better to be safe than to have them suffer any adverse effects on their growth and development. Insist on having brand name forms of Levothyroxine prescribed by your pediatrician.
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