This is why many physicians strongly recommend that their thyroid patients take only a brand name levothyroxine, and will even mark "Dispense as Written (DAW)" or check "no substitutions" on a brand-name levothyroxine prescription to ensure that generics are not dispensed.
But if if many doctors believe that generics don't offer consistent potency from batch to batch, and there are known health implications of inconsistent levothyroxine potency, then why is there a controversy?
The issue, as often in medicine, comes down to money.
Millions of Americans are in HMOs and insurance programs where cost-saving measures mandate use of generic drugs in almost all circumstances. Various generic levothyroxine drugs began to receive FDA approval in since 2001, and since that time, many thyroid patients have had no choice but to take the generic levothyroxine.
To understand the cost implications, consider these numbers. As of October 2006, the cost for a typical three-month supply of levothyroxine -- 90 pills of 88 mcg Synthroid -- is $41.99 at Drugstore.com. The same quantity and dosage of generic levothyroxine is $23.63. Over a year, this cost difference represents a nearly $75 savings per year. Considering that an estimated 13 million people are taking thyroid hormone replacement drugs, this $75 a year represents a cost differential of $975 million for insurers, HMOs and patients paying out-of-pocket for their medications.
The consortium resists the idea that generics generate cost savings, however. Leonard Wartofsky, MD, MACP, the President of The Endocrine Society, points out that "although it has been suggested that switching patients to less expensive brands or generic formulations of levothyroxine could result in cost savings, such savings can be outweighed by costs associated with adverse effects and additional physician visits to measure TSH and retitrate dosage."
The consortium also takes issue with the methodology used by the FDA to establish that the generic and brand names are bioequivalent is flawed. They would like the FDA to use Thyroid Stimulating Hormone (TSH) to establish effectiveness and bioequivalence.
The Unspoken IssueOne issue that the consortium does not mention, however, which raises questions about the extent of their argument, is the financial relationship between these three organizations and the top-selling levothyroxine drug, Synthroid. Synthroid's current manufacturer, Abbott Labs, and its former manufacturers, Knoll/BASF and Boots, have been financial supporters of the three thyroid-related organizations. As one of the top five selling drugs in America, Synthroid has had a close relationship with all three organizations, providing financial support for their annual meetings, advertising in their journals, reimbursing speakers and paying honorarium for sponsored presentations at medical meetings around the country, hosting and paying for lunches, cocktail parties and various events on behalf of these organizations, and funding research projects and grants for many of the organizations' leaders. The manufacturer also provides free drug samples -- as well as merchandise including patient literature, office supplies, educational posters, etc., -- to many member doctors' offices.
So these organizations rely on the financial support of Synthroid's manufacturer for many research, operational, educational and organizational activities.
At the same time, Synthroid is feeling the heat from the availability -- and lower cost -- of the generic levothyroxine. According to RxList.com, 30,695,000 prescriptions for Synthroid were dispensed in 2005. And in 2005, for the first time, generic levothyroxine prescriptions outpaced Synthroid, with 32,465,000 prescriptions. (The nearest brand name prescribed was Levoxyl, with only 12,772,000 prescriptions in 2005.) The shift to generic is clearly coming mainly from Synthroid's market share, because in 2004, 44,056,176 prescriptions for Synthroid were written. In one year, Synthroid lost in business a total number of prescriptions equal to the total its closest competitor dispenses in a year. Clearly, if the FDA maintains its current equivalence standards, Synthroid's market share will continue to erode.