The Food and Drug Administration wants to add its sternest warning to heartburn drug metoclopramide after cases of muscle spasms were reported in people taking it for long periods of time or at high doses.

 

“The chronic use of metoclopramide therapy should be avoided in all but rare vases where the benefit is believed to outweigh the risk,” said Dr. Janet Woodcock, director of FDA’s drug center.

 

Metoclopramide comes in a variety forms, including injections and edible syrups. The drug works by speeding up the muscles used in digestion and relieving painful stomach acid reflux. It is used as a short-term treatment of gastroesophageal reflux disease in patients who have not responded to other therapies, and to treat diabetic gastroparesis.

 

Current labeling of the drug already mentions risks of developing the spasms, called dyskinesia, a neurological disorder that can be a side effect of some types of drugs. Now the FDA wants to strengthen the idea by adding a black box warning, which appears at the top of drug labels.

 

The FDA said the elderly and people who have been on the drug for a long time are at highest risk.

 

Metoclopramide is currently used by more than two million Americans. The drug is sold under brand names including Reglan Tablets, Reglan Oral Disintegrating Tablets, Metoclopramide Oral Solution and Reglan Injection.