Ondansetron nervous system

Ondansetron is a 5HT3 antagonist, blocking serotonin receptors in the central nervous system and the gastrointestinal tract. It is useful in the management of postoperative nausea and vomiting associated with cytotoxics. 

Ondansetron antagonizes the action of serotonin at receptors in the upper gastrointestinal tract and in the chemoreceptor trigger zone of the central nervous system. Given intravenously (IV), it prevents vomiting completely for 24 h in 40% of patients treated with high doses (>100 mg/m2) of cisplatin and in 70 to 80% of patients treated with 50 to 100 mg/m2 of cisplatin or a combination of cyclophosphamide and doxorubicin. 

Ye JH, Hunt T, Wu WH, McArdle JJ. Ondansetron modulates GABA(A) current of rat central nervous system neurons. Eur J Pharmacol 1997 337 87-94. 

Nervous system Various nervous system adverse reactions to ondansetron have been reported. 

Nervous system A 26-year-old woman undergoing emergency cesarean delivery under spinal anesthesia with bupivacaine 10 mg was pre-medicated with intravenous ranitidine 50 mg and metoclopramide 10 mg, and received intramuscular diclofenac for postoperative analgesia [32 ]. Starting at 12 hours postoperatively she was given intravenous ondansetron 6 mg every 12 hours for nausea and vomiting. About 2 hours after the first dose she developed a severe headache, which persisted for over 90 hours and was characterized by aggravation of symptoms in coincidence with doses of ondansetron. The headache resolved completely a few hours after ondansetron withdrawal. 

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