Armour’s Back- a return of an old or maybe a new friend?

Hurray, Hurrah Armour thyroid is available again!
For those like me that prescribe Armour™, this puts an end to the pain of having to change people from Armour to one of the various types of thyroid supplementation available. In the past 6 months, I've changed people from Armour to Synthroid™, generic T4, Cytomel™, generic T3 (now available hurrah again), Nature-throid™, Westhroid™, compounded desiccated thyroid, T4 and T3, and every combination possible. We've dealt with dosages that were too much and too little from people who were perfectly controlled on their Armour prior to it not being available on the marketplace. But happily, we now seem to have a steady supply of our medications.

Of course, it's important to know that Armour isn't quite the same as it was, say 2 years ago. The company made some changes to the fillers in Armour. They decreased the dextrose (a sugar) and replaced it with cellulose (a fiber) and added cornstarch (fiber). They did this to try to increase the absorbability of the tablet by improving its properties of disintegration. Unfortunately, thyroid is very picky. When you change the fillers or binders in thyroid supplementation it will change absorption by 20%. Up or down. We know this because even going from brand name Synthroid to generic T4 (same dosage) may change absorption for patients. This was quite the nightmare before it was discovered. Patients were getting generics by different companies every month or were regularly changed from Synthroid to generic to Synthroid again. Symptoms would be great, then worsen (which led to lab testing showing inadequate or excessive dosing), which then would be altered, only to be completely problematic when they next filled their prescription. With generic brands being made by multiple companies, the label would stay the same - T4, but the colors of the pills would give it away - pink, then green, then pink again. Thankfully, someone finally realized that the fillers and binders in thyroid make all the difference - approximately 20% in fact.

So, Armour changed their fillers and what happened? Search for Armour reformulation and you can read the horrors. Patients who were stable on 60mg all of a sudden were hypothyroid again. Now, they needed 90mg or more; rarely they needed less. Basically, it was like changing to a completely different thyroid medication. Some patients have actually had such a hard time metabolizing their tablets that even increasing the dosage didn't help. This should not have been a surprise to Forest Pharmaceuticals the manufacturers of Armour. Individuals with thyroid dysfunction often have problems with digestion. Most triggers for Hashimoto’s (the most common reason for becoming hypothyroid) are gastrointestinal triggers and 50% of patients with Hashimoto’s have antibodies to their own gastric cells (http://www.thyroidmanager.org/Chapter10/chapter10.html) which means that digestion is compromised. For those people, changes in fillers and binders make huge differences. For many this meant a return of old symptoms, but for people on multiple medications this may have had severe consequences as other medication potency increased from a severely decreased metabolic clearance. How many problems due to this is unknown.

This formulation change took place in the spring of 2009 and was unpublished at the time. No doctors or pharmacies were notified. Then, while I was still trying to figure this out, Armour disappeared. I personally wondered if it was due to the change in formulation. The rumors started flowing; implicating the FDA, new drug applications, permanent stop in manufacturing, stop in all desiccated thyroid products etc. However, it soon became clear that the raw materials were unavailable, but why? Good question. The fact that Armour is from pigs and H1N1 (swine flu) was rampant at the time seems a bit suspicious, but unconfirmed. But the sad result was this thyroid supplementation was gone and soon all other desiccated thyroid products followed. For patients who have doctors who love the thyroid, this was an inconvenience, but generally easily switched to some combination of T4 and T3. Since any change requires some fiddling, it commonly took another 1-2 months before we were both sure that this was the right dosage. But, since once again we were changing fillers, the likelihood of increasing or decreasing dosages was common. For patients who don't have healthcare providers that understand thyroid, they have had to put up with T4 only therapy being told it will do the same thing (which it isn't) and is better (debatable). For those individuals who don’t convert well between T4 and T3, they have suffered. So, I'm thrilled that Armour and Naturethroid and Westhroid (same product with two names) are back. Although I think that there is no such thing as the right way to treat hypothyroidism, I personally find these forms to be well tolerated, inexpensive, very effective, and convenient for many patients.

I believe that this fiasco has brought to clear attention how delicate and dependant we all are on the flow of medications. I think that it also brings to clear attention the "inactive" ingredients so commonly ignored by myself and other prescribers. They are the reasons that generics and brand names may be very different. I would also like to see Forest Laboratories and others make a policy of notifying pharmacies in the future that their product fillers have changed and therefore dosages may need adjustment. It also brings to light the helpfulness in the internet in linking people with common complaints. It is of course, how I,a physician, found out what was going on. I know that the researchers at Forest thought that this would be a small change, not noticed and of no significance, and I'm sure that some didn't. But for those that did - Hurrah, Hurrah your Armour is back, it just might need some dose adjustments.

Now, what happened to Thyrolar™?
Alison McAllister, ND
PS. Please note this is not about which is the right thyroid or why one is better than another or all the options available. This is about fillers and the impacts they have on what should essentially be the same medication.

• http://www.armourthyroid.com/ - Forest Laboratories; has a handy calculator if you are switching from T4 to Armour. Fun fact, Armour got its name from the animal processing plant that harvested the thyroid glands.


• Westhroid- a look at inactive ingredients put into supplements. A nice review from Westhroid a T4/T3 combination medication


• http://thyroid.about.com/ - I highly recommend this site to my patients as well as other healthcare professionals. As a blog about thyroid, Ms Shomon has provided invaluable information about the changes to Armour. She continues to watch the situation closely.


• http://www.thyroidmanager.org/ - for those that love the deep gory biochemical details. Fabulous. Dr DeGroot and her team have done an amazing job in putting together the best thyroid textbook I've seen yet (If you know of a better let me know!).

Proof that stability is a big issue in ALL THYROID BRANDS.

Thyroid. 2009 Feb;19(2):103-10.
TSH-based protocol, tablet instability, and absorption effects on L-T4 bioequivalence.
Eisenberg M, Distefano JJ.
Biocybernetics Laboratory, Departments of Computer Science , Medicine and Biomedical Engineering, UCLA, Los Angeles, California.

BACKGROUND: FDA Guidance for pharmacokinetic (PK) testing of levothyroxine (L-T(4)) for interbrand bioequivalence has evolved recently. Concerns remain about efficacy and safety of the current protocol, based on PK analysis following supraphysiological L-T(4) dosing in euthyroid volunteers, and recent recalls due to intrabrand manufacturing problems also suggest need for further refinement. We examine these interrelated issues quantitatively, using simulated what-if scenarios testing efficacy of a TSH-based protocol and tablet stability and absorption, to enhance precision of L-T(4) bioequivalence methods. METHODS: We use an updated simulation model of human thyroid hormone regulation quantified and validated from data that span a wide range of normal and abnormal thyroid system function. Bioequivalence: We explored a TSH-based protocol, using normal replacement dosing in simulated thyroidectomized patients, switching brands after 8 weeks of full replacement dosing. We simulated effects of tablet potency differences and intestinal absorption differences on predicted plasma TSH, T(4), and triiodothyronine (T(3)) dynamics. Stability: We simulated effects of potency decay and lot-by-lot differences in realistic scenarios, using actual tablet potency data spanning 2 years, comparing the recently reduced 95-105% FDA-approved potency range with the original 90-110% range. RESULTS: A simulated decrease as small as 10-15% in L-T(4) or its absorption generated TSH concentrations outside the bioequivalence target range (0.5-2.5 mU/L TSH), whereas T(3) and T(4) plasma levels were maintained normal. For a 25% reduction, steady-state TSH changed 300% (from 1.5 to 6 mU/L) compared with but tablets of the same dose strength and brand were not bioequivalent between lots and between fresh and near-expired tablets. CONCLUSIONS: A pharmacodynamic TSH-measurement bioequivalence protocol, using normal L-T(4) replacement dosing in athyreotic volunteers, is likely to be more sensitive and safer than current FDA Guidance based on T(4) PK. The tightened 95-105% allowable potency range for L-T(4) tablets is a significant improvement, but otherwise acceptable potency differences (whether due to potency decay or lot-by-lot inconsistencies) may be problematic for some patients, for example, those undergoing high-dose L-T(4) therapy for cancer. PMID: 19191742 [PubMed - indexed for MEDLINE]Pasted from