What is the difference between Armour, Thyrolar and the levothyroxine sodium drugs? Primarily, Armour and Thyrolar are drugs that provide BOTH T4 and T3 thyroid hormones, instead of just providing T4, as levothyroxine sodium drugs like Synthroid do.
Current endocrinology practice believes that T4-only drugs are the ONLY appropriate thyroid hormone replacement drugs. The prevailing opinion is that everyone converts all the T4 needed into T3 automatically, and that drugs such as Armour and Thyrolar are outdated and old-fashioned at best. Some doctors are even vehement about this, and swear that Armour has consistency problems or is dangerous, despite the fact that is was the primary thyroid replacement hormone drug for years, until Synthroid came on the market. Also, in terms of consistency problems, the levothyroxine sodium drugs have recently come under heavy FDA fire for problems with stability and potency. (See my article "Synthroid and other Levothyroxine Drugs Have Significant Stability and Potency Problems," located at http://thyroid.about.com/library/weekly/aa090197.htm.)
Generally, most people do fine on levothyroxine sodium T4-only drugs. But some people do not. These people may be candidates for Armour or Thyrolar.
My Own Experience:
After diagnosis, I spent a year and half on Thyrolar, as prescribed by my osteopathic MD, and was doing pretty well. After reading constantly about how the T4 only drugs were the "gold standard," I asked my doctor to switch me to Synthroid. Immediately, I started to lose my hair very rapidly. Within two months, despite my TSH test as showing still in the "normal" range, my usual 28-day menstrual cycle with normal 5 day periods went to every 22 days, lasting 7 days, and were unusually heavy and painful. Then I developed an ovarian cyst, which is associated with untreated hypothyroidism. After a few more months of hair loss, menstrual irregularities, and exhaustion, despite normal TSH levels, my doctor and I decided that I should go back to the Thyrolar. Symptoms resolved themselves within two months, and I was again back to normal. I stayed on Thyrolar for several years, before switching over to Armour, which I've been on since the late 1990s. ever since.
Here is descriptive information from the package inserts:
Armour Thyroid tablets for oral use are natural preparations derived from porcine [pork] thyroid glands. Inactive ingredients are calcium stearate, dextrose, microcrystalline cellulose, sodium, starch glycolate and opadry white (titanium dioxide used as a whitening agent). Armour Thyroid is available in 1/4 grain, 1/2 grain, 1 grain, 1 1/2 grain, 2 grain, 3 grain, 4 grain and 5 grain tablet strengths.
Also, according to informational literature sent out by Forest Pharmaceuticals, Inc.,
"Because Armour Thyroid medications require a 4.22 to 1 ratio of T4 to T3, batches of desiccated thyroid are mixed until the desired ratio is obtained. This method ensures that each strength of Armour Thyroid will be consistent every time."
Thyrolar (generic name Liotrix)
Thyrolar contains triiodothyronine (T3, liothyronine) sodium and tetraiodothyronine (T4 levothyroxine) sodium. Inactive ingredients are calcium phosphate, colloidal silicon dioxide, cornstarch, lactose, magnesium stearate. The following dies are also used:
- Thyrolar 1/4 -- FD&C Blue #1 and FD&C Red #40.
- Thyrolar 1/2 -- FD&C Red #40 and D&C Yellow #10
- Thyrolar 1 -- FD&C Red #40
- Thyrolar 2 -- FD&C Blue #1, FD&C Red #40 and D&C Yellow #10
- Thyrolar 3, FD&C Red #40 and Yellow #10
For More Information on Finding a Doctor Willing to Consider Prescribing Armour or Thyrolar...
Consider finding a doctor through the Broda Barnes Foundation, or finding a holistic or naturopathic doctor, as these doctors are most often those who are familiar with working with these drugs in the treatment of thyroid disease. You can read about this in my article, "Finding the Best Doctor Who's Right for YOU! -- Referral Sources," located at http://thyroid.about.com/library/weekly/aa100697.htm.
For More Information on Armour or Thyrolar, contact:
Forest Pharmaceuticals, Inc.
Their contact information is in the Thyroid Drugs Database entry for Forest