Because psychiatrists have experience using dopamine-blocking drugs, they know of the risk of tardive dyskinesia and watch for its symptoms, Jankovic says. Metoclopramide, on the other hand, "is prescribed by internists or gastroenterologists who are not necessarily familiar with the recognition of tardive dyskinesia."
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How big is the risk?
Jankovic analyzed all 443 tardive dyskinesia patients seen over 25 years at his Baylor clinic. Prior to 2000, the antipsychotic Haldol was the main culprit; since then, metoclopramide has moved to first place.
"It is a public health problem," Jankovic says. "Many of these patients who have metoclopramide-induced movement disorders aren't recognized until . . . they're at pretty advanced stages of the disease."
The main way to limit the risk is by limiting how long the drug is used. The drug is already labeled for short-term use, defined as four to 12 weeks. But a 2007 FDA study found that 20% of patients were prescribed the drug for longer than this.
These studies provide, in part, the basis for the FDA's decision to require a boxed warning, which is aimed at alerting physicians, says FDA spokeswoman Rita Chappelle. "We've known for years that tardive dyskinesia was a concern with this drug, but what we're trying to highlight in the box is the risk of chronic use."
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Are there alternatives?
Yes. Unlike metoclopramide, the antinausea drug Zofran doesn't block dopamine. There are prescription-strength drugs for reflux that reduce gastric acid rather than increase motility, such as the H2 blockers Zantac and Tagamet and the proton pump inhibitors Prilosec and Prevacid.
"Metoclopramide, clearly, is an effective drug," Jankovic says. "But if the drug has to be used for longer than a few weeks, then I think it's prudent to switch the patient to these other drugs -- even if they're less effective."
