Unusual reactions to 5‐HT3 receptor antagonists in a child with rhabdomyosarcoma

Abstract

Ondansetron and granisetron are 5‐HT3 receptor antagonists commonly used for prevention of chemotherapy‐induced nausea and vomiting. Rare acute dystonic reactions to ondansetron have been reported previously. We report a case of abnormal facial movements associated with granisetron.A boy with prostatic rhabdomyosarcoma and lung and bone metastases developed abnormal facial movements while receiving ondansetron 4 mg po q8h (5 mg/m2/dose). These movements consisted of involuntary blinking of the eyes, pursing of the lips, forward thrusting of the jaw and protrusion of the tongue. After excluding other potential causes, the diagnosis of ondansetron‐induced movement disorder was made. These movements decreased when the dose of ondansetron was reduced and resolved with its discontinuation. On admission for a subsequent cycle of chemotherapy, the patient was treated with granisetron 480 µg iv q12h (20 µg/kg/dose). On day 3, the patient developed repeated forward thrusting of the jaw and simultaneous blinking of the eyes, which were self‐limiting and less severe than those associated with ondansetron use. As vomiting was effectively prevented, granisetron was continued until completion of therapy. Health professionals need to be aware of these possible, albeit rare, reactions to ondansetron and granisetron in paediatric oncology patients.Supported by Hospital for Sick Children Research Institute (CL, GK)