BACKGROUND: Extrapyramidal syndromes (EPS) are clinically relevant side
effects of metoclopramide which are often not anticipated. PATIENTS AND
METHODS: Two patients who received metoclopramide developed an acute
dystonic reaction. Symptoms disappeared after biperiden or trihexyphenidyl
were given. Molecular analysis of the CYP2D6 gene was performed using a
PCR-based method. RESULTS: Both patients were homozygous for inactive
CYP2D6 alleles (CYP2D6*4/*4 and CYP2D6*4/*5), which are associated with
slow drug metabolism. CONCLUSION: Metoclopramide-induced acute dystonic
reactions may occur in patients carrying a CYP2D6 genetic polymorphism