FDA Opens Door for Generic Synthroid

But Will You Want It?

Instead, the FDA decided to add a baseline correction to its current protocol for levothyroxine bioequivalence. According to Abbott experts, the correction factor still leaves a risk of as much as a 12.5% difference between one brand and its generic at the same dosage.

In an interview with Mary Shomon, Jeff Leshay, Abbott Laboratories' Director of Public Affairs for the Pharmaceutical Products Division, expressed the company's disappointment at the outcome of the FDA meeting, but felt that the baseline correction was an important step forward.

Said Leshay: "We continue to feel that even this adjustment to the guidelines is not sufficient because our studies showed that differences in doses of up to 12 .5% could still be judged the same, and therefore be judged as therapeutically interchangeable. The slight differences in doses can have adverse health consequences for patients. That is of particular concern to us."

Abbott is also interested in seeing the TSH test, rather than T4 measurements, as part of the bioequivalence criteria.

Says Abbott's Leshay: "Based on our data we think there is a need to test TSH as part of the approach to determine bioequivalence, and that's not currently part of the methodology."

Is It a Synthroid Marketing Ploy?

Synthroid has been a highly profitable drug for Abbott, generating $520 million in global sales in 2002, up 11.3 percent from the previous year. As of 2002, it was the second-most prescribed medication in the United States and among Abbott's top-selling drugs. It has consistently been the top-selling thyroid drug in the U.S.

So, is the latest move by Abbott's labs just another in a string of efforts to delay competition for Synthroid?

Abbott's Leshay insists that the motives are purely altruistic. Says Leshay: "We know that generic competition is a fact of life. But we want to ensure that as a leader in this therapeutic area, in the interest of patient safety, that true bioequivalence is achieved, within a very tight range, so that patients who are particularly sensitive to dosage amounts and titration get exactly the dose that they need."

But critics note that this is not the first time that Abbott has used what appear to be stalling tactics to try to protect its market share for Synthroid.

In 1997, the FDA called for all levothyroxine drugs to go through the new drug application (NDA) process by August of 2000. Synthroid's manufacturers stalled the process, deluging the FDA with numerous Freedom of Information Act (FOIA) requests for every document pertaining to levothyroxine. This resulted in an extension of the original deadline to August of 2001. After the deadline extension was denied, Synthroid's makers then insisted that the drug did not need to go through the FDA's NDA process, because the drug should be grandfathered in under "Generally Recognized as Safe and Effective (GRAS/GRE) status.

The FDA denied Synthroid's request, issuing a scathing 9-page letter that outlined what the FDA said was Synthroid's long history of manufacturing problems, subpotency concerns, and stability and reliability issues.

Abbott then turned to arguing that the August 2001 deadline was to submit an application, not approval of the application. The FDA, however, ruled against the company once again, and ordered a mandatory stepped ramp-down of sales of unapproved Synthroid, leading up to a complete ban on sales of Synthroid by August of 2003, unless the product received full FDA approval.

Synthroid also came up against the bioequivalence issue back in the 1990s, when its manufacturer at the time, Boots Pharmaceutical, commissioned a research study to prove a marketing claim that competitive products were not bioequivalent to Synthroid, and that justified Synthroid's substantially higher prices. When the study results showed that the competitive products were in fact bioequivalent to Synthroid, the company allegedly attempted to suppress the findings of the study. Eventually, the Journal of the American Medical Association published the study against the wishes of the manufacturer, which was then Knoll Pharmaceuticals and multinational parent company BASF. Based on those findings, a multi-million dollar class action lawsuit was filed against the manufacturer, claiming that millions of patients had been overcharged for Synthroid during the years that the research study went unpublished. The lawsuit was quickly settled in 1997 by the manufacturer for a small percentage of the estimated overpayments, but the final approval of the settlement has remained in legal limbo since that time, and patients who filed to be part of the settlement have yet to receive any payments.

Meanwhile, Synthroid still charges substantially more than its competition. (See Thyroid Drug Prices, February 2003.)