Metoclopramide, an Increasingly Recognized Cause of Tardive Dyskinesia

T dyskinesia (TD), a hyperkinetic movement disorder causally related to dopamine receptorblocking drug (DRBD) exposure, is a well-recognized iatrogenic disorder in adults and less commonly seen in children and infants. Although the literature on TD mainly focuses on patients treated with DRBDs used as antipsychotics, DRBDs are also used to treat a wide array of medical, chiefly gastrointestinal, conditions. Although most of the drugs that cause TD are DRBDs that antagonize dopamine D2 receptors, other classes of drugs have the potential to cause TD, including antidepressants and calcium channel blockers. The reported lifetime prevalence of TD in patients treated with traditional DRBDs has varied greatly, with an average of about 25% of exposed adults. Risk factors associated with the development of TD include advanced age, female gender, and, more important, total cumulative drug exposure. We sought to determine which drugs most commonly cause TD in patients referred to our clinic.