The FDA recently announced that Acella Pharmaceuticals was recalling lots of NP Thyroid found to be “super potent.” NP Thyroid is a version of Thyroid USP, also called natural desiccated thyroid or porcine thyroid. The products were said to have up to 115% the labeled about of T3 hormone. The recall is only for specific lots manufactured before May 2019, and did not affect 15mg or 120mg tablets.  Detailed information from NP Thyroid can be found on their website here: https://npthyroid.com/product-updates/.

How Much More Potent is the Recalled Product?

It is important to note that it is considered acceptable to have a range of 90% to 110% of the labeled amount of thyroid hormone in natural desiccated thyroid. This is because of the method of making the product from animal thyroid glands. Since all animals can have different levels of thyroid hormone within a certain range, there can be some variation between batches even with rigorous testing.

The 115% of expected T3 potency, with a correct T4 potency, likely will not result in negative side effects for the majority of patients. However for some patients it may result in adverse effects. Adverse effects of receiving the super potent thyroid medication may include signs and symptoms of hyperthyroidism (overactive thyroid) such as “weight loss, heat intolerance, fatigue, muscle weakness, hypertension, chest pain, rapid heart rate, or heart rhythm disturbances.” In addition, “Pregnant women who take superpotent NP Thyroid may also experience negative maternal and fetal outcomes including miscarriage and/or impairment to fetal development.” Two adverse patient events have been reported from the super potent lots to-date.

What is Natural Desiccated Thyroid?

Natural desiccated thyroid extract is made from the thyroid glands of animals – usually pigs but also cows and sheep. NDT was actually the first type of thyroid hormone replacement and has been used for over 100 years. Because it was used before the FDA started regulating medications, it was effectively “grandfathered” in and continues to be available without official FDA approval. This may change in the future as the FDA may require manufacturers to submit New Drug Applications (NDAs) for their desiccated thyroid products. There is a balance between making sure that patients using these medications can still get their treatment and also making sure there is consistency in the quality and potency of the manufactured drugs.

Why Use Natural Desiccated Thyroid?

If natural desiccated thyroid has the potential for variances in potency between batches, then why do doctors continue to prescribe it? For the majority of patients these slight variations do not have an effect. The benefits of NDT cited by doctors include the fact that it contains all forms of the thyroid hormone, including T4 and T3, as well as thyroid co-factors. NDT has a high patient satisfaction rate, and many patients who have tried synthetic T4 find that it is not enough to alleviate their symptoms. It is estimated that up to 10-25% of patients with hypothyroidism use NDT instead of a synthetic product.

While the benefits of each type of thyroid therapy continue to be debated, patients continue to choose NDT for their hypothyroidism treatment. In one study, 34 patients (48.6%) preferred NDT, 13 (18.6%) preferred synthetic T4, and 23 (32.9%) had no preference. The increase in patients using NDT is partially due to the fact that many did not experience symptom relief when taking synthetic products. It may also be related to patients desiring a more natural treatment that is not made synthetically in a lab.

Compounded NDT

A compounding pharmacy can make natural desiccated thyroid capsules using the same active ingredient (Thyroid USP) as all of the brand-name thyroid medications. Because of slight variations in how each brand makes their product, such as the composition of inactive ingredients, most doctors recommend sticking with one brand as much as possible. Switching back and forth between brands can cause disruptions in hormone levels that result in a return of hypothyroid symptoms or possibly hyperthyroidism. Some patients have made the switch to a compounded NDT and stick with it because their brand experiences shortages or recalls. An example of this is the Nature Throid and WP Thyroid shortages that occurred recently, which have since been mostly resolved. Patients were left trying to find sources for their medication and many switched to other brands or to compounded alternatives as a result.

NP Thyroid and Future of NDT

Acella seems to have their issues with NP Thyroid under control, and all batches made after May 2019 are not affected by the recall. However in recent years there have been several issues with different NDT brands that have lead to disruptions in treatment for many patients. Compounded NDT remains an option for patients who are looking for a consistently available product that is custom made for them.

Links

FDA Announcement – Recalls, Market Withdrawals, Safety Alerts

NP Thyroid Recall – Notice to Patients

Desiccated Thyroid Extract Compared With Levothyroxine in the Treatment of Hypothyroidism: A Randomized, Double-Blind, Crossover Study – PubMed