Rate of administration of intravenous ondansetron.

Sir,

Ondansetron, a selective 5- HT3 receptor antagonist, is a popular drug for prevention and treatment of postoperative nausea and vomiting (PONV) because of its efficacy, safety and lack of drug interactions. Although rare, cardiovascular adverse effects such as sinus bradycardia, atrial fibrillation, prolongation of QTc interval and fatal ventricular tachycardia have been reported following administration of ondansetron.[1-4] A case of severe bradycardia with respiratory arrest and loss of consciousness has been described.[5] Most of the case reports regarding serious adverse effects, including that reported in Indian Journal of Anaesthesia by Sahu et al.,[4] do not describe the rate at which ondansetron had been administered to the patient. It is not uncommon for residents to administer ondansetron as a bolus perioperatively. Not many clinicians are aware that ondansetron 4 to 8 mg iv should be administered over 2 to 5 min[6] and certainly not as a bolus or in less than 30 s. Perhaps slow administration of ondansetron as recommended over 2-5 min would decrease the incidence of potentially life-threatening adverse effects associated with ondansetron.