Gastroparesis, metoclopramide, and tardive dyskinesia: Risk revisited
BACKGROUND: receptor agonist activity, and used as an antiemetic and gastroprokinetic since almost 50 years. Regulatory authorities issued restrictions and recommendations regarding long-term use of the drug at oral doses exceeding 10 mg 3-4 times daily because of the risk for development of tardive dyskinesia. The aim of our study was to review mechanism(s) of action and pharmacokinetic-pharmacodynamic properties of metoclopramide, as well as the risk of metoclopramide-induced tardive dyskinesia, factors that may change drug exposure in humans, and to summarize the clinical context for appropriate use of the drug. METHODS: A PubMed, Google Scholar, and Cross Reference search was done using the key words and combined searches: drug-drug interaction, gastroparesis, metoclopramide, natural history, pharmacokinetics, pharmacodynamics, drug-drug interaction, outcome, risk factors, tardive dyskinesia. KEY RESULTS: Data show that the risk of tardive dyskinesia from metoclopramide is low, in the range of 0.1% per 1000 patient years. This is far below a previously estimated 1%-10% risk suggested in treatment guidelines by regulatory authorities. High-risk groups are elderly females, diabetics, patients with liver or kidney failure, and patients with concomitant antipsychotic drug therapy, which reduces the threshold for neurological complications. CONCLUSIONS & INFERENCES: The risk of tardive dyskinesia due to metoclopramide is far below approximated numbers in treatment guidelines. This risk and the influence of known risk factors should be considered when starting a course of metoclopramide for treatment of gastroparesis.