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.