The pharmacokinetics of oral metronidazole in patients with metronidazole‐induced encephalopathy undergoing maintenance hemodialysis

Background Metronidazole‐induced encephalopathy (MIE) is a rare disease caused by an adverse reaction to metronidazole (MNZ). Furthermore, the pharmacokinetics of MNZ during hemodialysis (HD) treatment have not been revealed. Case presentation In a 70‐year‐old woman undergoing maintenance HD, MNZ was administered intermittently for the treatment of recurrent hepatic cyst infections. She complained of vomiting, dizziness, and dysarthria after 65 consecutive days of MNZ administration. In brain fluid‐attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI), we found a high signal intensity in the cerebellar dentate nuclei and splenium of the corpus callosum. We diagnosed the patient with MIE. MNZ administration was withdrawn immediately, and HD treatment was performed for 3 consecutive days. Accompanying the remarkable decrease in serum MNZ levels, MIE symptoms were attenuated after three consecutive days of HD. In a brain MRI at 9 days, the high‐intensity areas in the cerebellar dentate nuclei and splenium of the corpus callosum had disappeared. Conclusion In this patient, we diagnosed MIE in the early stage using MRI, and 3 consecutive days of HD rapidly attenuated the symptoms associated with MIE, accompanied by a significant decrease in serum MNZ levels.