Late last month, the Food and Drug Administration ruled that makers of the drug metoclopramide must put the strongest so-called black-box warning on the product's package insert. Also sold as Reglan, Octamide and Maxolon, metoclopramide is used to treat certain gastrointestinal problems. If taken chronically, it can cause a serious neurological disorder called tardive dyskinesia (TD).
What's metoclopramide?
Metoclopramide is used to treat the slow stomach-emptying that can occur in diabetes, and as a second-line treatment for heartburn caused by gastroesophageal reflux. It's sometimes used for the nausea and vomiting that accompany cancer treatment, and migraines.
The drug stimulates the stomach to move things along, reducing fullness and reflux of the stomach's contents. It also quashes the urge to vomit. It works by blocking dopamine, a neurochemical that induces vomiting and stomach-slowing.
What is TD?
Tardive dyskinesia is a disorder in which the tongue, mouth and jaw move uncontrollably in abnormal ways. Movements can include eye-blinking and face-jerking, and can occur elsewhere on the body. The movements are "pretty much constant," says Dr. Jeff Bronstein, a neurologist at UCLA's David Geffen School of Medicine, except during sleep.
The disorder can persist for months and years, and in some cases appears to be permanent. Severity can vary, Bronstein says. "Some people can get so bad it's hard for them to eat and swallow because of their tongue movements. And obviously, cosmetically, it's horrible."
Tardive dyskinesia occurs as a side effect of drugs that block dopamine. Once diagnosed, patients are usually taken off the drug. "In some patients, the symptoms get better," says Dr. Joseph Jankovic, a neurologist at Baylor College of Medicine in Houston. "But in many cases, it becomes a permanent neurological disorder." No standard therapy exists, but various drugs have been used as treatments.
Do other drugs cause it?
Antipsychotics such as Haldol and Thorazine also block dopamine receptors, and their long-term use has long been known to cause TD. Studies estimate that the disorder ultimately occurs in up to 25% of patients taking dopamine-blocking drugs.
These days, psychiatrists reach for newer drugs called atypical antipsychotics, such as Zyprexa and Clozaril, which have a lower propensity to cause tardive dyskinesia.
