The metoclopramide black box warning for tardive dyskinesia: effect on clinical practice, adverse event reporting, and prescription drug lawsuits.

OBJECTIVES: We examined the effects of the black box warning about the risk of tardive dyskinesia (TD) with chronic use of metoclopramide on management of gastroparesis within a single clinical practice, and on reporting of adverse events.

METHODS: Medical records of gastroparesis patients were evaluated for physician management choices. The FDA Adverse Event Reporting System (FAERS) was analyzed for event reports, and for lawyer-initiated reports, with metoclopramide from 2004 to 2010. Google Scholar was searched for court opinions against metoclopramide manufacturers.

RESULTS: Before the black box warning, 69.8% of patients received metoclopramide for gastroparesis, compared with 23.7% after the warning. Gastroenterologists prescribed domperidone more often after than before the warning. Metoclopramide prescriptions decreased after 2008. Adverse event reporting increased after the warning. Only 3.6% of all FAERS reports but 70% of TD reports were filed by lawyers, suggesting a distortion in signal. Forty-seven legal opinions were identified, 33 from 2009-2010.

CONCLUSIONS: The black box warning for metoclopramide has decreased its usage and increased its rate of adverse event reporting. Lawyer-initiated reports of TD hinder pharmacovigilance.