Hypersensitivity Reactions

Inform patients that Ondansetron Injection may cause hypersensitivity reactions, some as severe as anaphylaxis and bronchospasm. The patient should report any signs and symptoms of hypersensitivity reactions, including fever, chills, rash, or breathing problems [see Warnings and Precautions (5.1)]

QT Prolongation

Patients should be informed that Ondansetron Injection may cause serious cardiac arrhythmias, such as QT prolongation. Patients should be instructed to tell their healthcare provider right away if they perceive a change in their heart rate, if they feel lightheaded, or if they have a syncopal episode.

Patients should be informed that the chances of developing severe cardiac arrhythmias, such as QT prolongation and Torsade de Pointes are higher in the following people:

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Patients with a personal or family history of abnormal heart rhythms, such as congenital long QT syndrome;

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Patients who take medications, such as diuretics, which may cause electrolyte abnormalities;

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Patients with hypokalemia or hypomagnesemia.

Ondansetron Injection should be avoided in these patients, since they may be more at risk for cardiac arrhythmias, such as QT prolongation and Torsade de Pointes [see Warnings and Precautions (5.2)].

Drug Interactions

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Instruct the patient to report the use of all medications, especially apomorphine, to their healthcare provider. Concomitant use of apomorphine and Ondansetron Injection may cause a significant drop in blood pressure and loss of consciousness.

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Advise patients of the possibility of serotonin syndrome with concomitant use of Ondansetron Injection and another serotonergic agent, such as medications to treat depression and migraines. Advise patients to seek immediate medical attention if the following symptoms occur: changes in mental status, autonomic instability, neuromuscular symptoms with or without gastrointestinal symptoms [see Warnings and Precautions (5.3)].

Myocardial Ischemia

Inform patients that Ondansetron Injection may cause myocardial ischemia during or after the administration. Advise patients to seek immediate medical help if any symptoms suggestive of a myocardial ischemia occur, such as sudden chest pain or chest tightness [see Warnings and Precautions (5.4)].

Masking of Progressive Ileus and Gastric Distension

Inform patients following abdominal surgery or those with chemotherapy-induced nausea and vomiting that Ondansetron Injection may mask signs and symptoms of bowel obstruction. Instruct patients to immediately report any signs or symptoms consistent with a potential bowel obstruction to their healthcare provider [see Warnings and Precautions (5.5)].