Ondansetron

Ondansetron is indicated for the prevention of nausea and vomiting associated with: • highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m 2 • initial and repeat courses of moderately emetogenic cancer chemotherapy • radiotherapy in patients receiving either total body irradiation, single high-dose fraction to the abdomen, or daily fractions to the abdomen Ondansetron is also indicated for the prevention of postoperative nausea and/or vomiting. Ondansetron is a 5-HT 3 receptor antagonist indicated for the prevention of: • nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m 2 . …

• See full prescribing information for the recommended dosage
• In adults and pediatrics. • Patients with severe hepatic impairment: do not exceed a total daily dose of 8 mg
• Recommended Dosage The recommended dosage regimens for adult and pediatric patients are described in Table 1 and Table 2, respectively
• Corresponding doses of ondansetron tablets, and ondansetron orally disintegrating tablets may be used interchangeably
• Table 1: Adult Recommended Dosage Regimen
• For Prevention of Nausea and Vomiting Indication Dosage Regimen Highly Emetogenic Cancer Chemotherapy A single 24-mg dose administered 30 minutes before the start of single-day highly emetogenic chemotherapy, including cisplatin greater than or equal to 50 mg/m 2
• Moderately Emetogenic Cancer Chemotherapy 8 mg administered 30 minutes before the start of chemotherapy, with a subsequent 8-mg dose 8 hours after the first dose
• Then administer 8 mg twice a day (every 12 hours) for 1 to 2 days after completion of chemotherapy
• Radiotherapy For total body irradiation: 8 mg administered 1 to 2 hours before each fraction of radiotherapy each day
• For single high-dose fraction radiotherapy to the abdomen: 8 mg administered 1 to 2 hours before radiotherapy, with subsequent 8-mg doses every 8 hours after the first dose for 1 to 2 days after completion of radiotherapy
• For daily fractionated radiotherapy to the abdomen: 8 mg administered 1 to 2 hours before radiotherapy, with subsequent 8-mg doses every 8 hours after the first dose for each day radiotherapy is given. …

Ondansetron Tablets, USP are oval, standard convex, film-coated tablets and are available in the following strengths: • 4 mg - white tablet with ‘4’ on one side and ‘G1’ logo on the other side • 8 mg - yellow tablet with ‘8’ on one side and ‘G1’ logo on the other side Ondansetron Orally Disintegrating Tablets, USP are white, circular, flat faced, uncoated tablets and are available in the following …

• The safety and effectiveness of orally administered ondansetron have been established
• In pediatric patients 4 years and older for the prevention of nausea and vomiting associated with moderately emetogenic cancer chemotherapy
• Use of ondansetron in these age-groups is supported by evidence from adequate and well-controlled studies of ondansetron
• In adults with additional data from 3 open-label, uncontrolled, non-US trials in 182
• Pediatric patients aged 4 to 18 years with cancer who were given a variety of cisplatin or noncisplatin regimens [see Dosage and Administration , Clinical Studi …

Of the total number of subjects enrolled in cancer chemotherapy-induced and postoperative nausea and vomiting in US- and foreign-controlled clinical trials, for which there were subgroup analyses, 938 (19%) were aged 65 years and older. No overall differences in safety or effectiveness were observed between subjects 65 years of age and older and younger subjects. …

• Hypersensitivity Reactions Inform patients that ondansetron may cause hypersensitivity reactions, some as severe as anaphylaxis and bronchospasm
• Instruct patients to immediately report any signs and symptoms of hypersensitivity reactions, including fever, chills, rash, or breathing problems to their healthcare provider [see Warnings and Precautions ]
• QT Prolongation Inform patients that ondansetron may cause serious cardiac arrhythmias, such as QT prolongation
• Instruct patients 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 [ see Warnings and Precautions ]. …

Ondansetron is contraindicated in patients: • known to have hypersensitivity (e.g., anaphylaxis) to ondansetron or any of the components of the formulation [see Adverse Reactions ( 6.2 )] • receiving concomitant apomorphine due to the risk of profound hypotension and loss of consciousness Patients known to have hypersensitivity (e.g., anaphylaxis) to ondansetron or any components of the formulation. ( 4 ) • Concomitant use of apomorphine. ( 4 )

7.1 Serotonergic Drugs Serotonin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has been described following the concomitant use of 5-HT 3 receptor antagonists and other serotonergic drugs, including SSRIs and SNRIs. Monitor for the emergence of serotonin syndrome. If symptoms occur, discontinue ondansetron and initiate supportive treatment [see Warnings and Precautions ( 5.3 )] . 7.2 Drugs Affecting Cytochrome P-450 Enzymes Ondansetron does not itself appear to induce or inhibit the cytochrome P‑450 drug‑metabolizing enzyme system of the liver [see Clinical Pharmacology ( 12.3 )] . …

• Hypersensitivity Reactions Including Anaphylaxis and Bronchospasm : Discontinue ondansetron if suspected. Monitor and treat promptly per standard of care until signs and symptoms resolve. ( 5.1 ) • QT Interval Prolongation and Torsade de Pointes : Avoid in patients with congenital long QT syndrome; monitor with electrocardiograms (ECGs) if concomitant electrolyte abnormalities, cardiac failure or arrhythmias, or use of other QT prolonging drugs. ( 5.2 ) • Serotonin Syndrome : Reported with 5-HT 3 receptor antagonists alone but particularly with concomitant use of serotonergic drugs. If such symptoms occur, discontinue ondansetron and initiate supportive treatment. …

The following clinically significant adverse reactions are described elsewhere in the labeling: • Hypersensitivity Reactions [see Warnings and Precautions ( 5.1 )] • QT Prolongation [see Warnings and Precautions ( 5.2 )] • Serotonin Syndrome [see Warnings and Precautions ( 5.3 )] • Myocardial Ischemia [see Warnings and Precautions ( 5.4 )] • Masking of Progressive Ileus and Gastric Distension [see Warnings and Precautions ( 5.5 )] The most common adverse reactions in adults for the: • prevention of chemotherapy-induced (≥5%) are: headache, malaise/fatigue, constipation, diarrhea. ( 6.1 ) • prevention of radiation-induced nausea and vomiting (≥2%) are: headache, constipation, and diarrhea. …

8.1 Pregnancy Risk Summary Published epidemiological studies on the association between ondansetron use and major birth defects have reported inconsistent findings and have important methodological limitations that preclude conclusions about the safety of ondansetron use in pregnancy (see Data) . Available postmarketing data have not identified a drug-associated risk of miscarriage or adverse maternal outcomes. …

There is no specific antidote for ondansetron overdose. Patients should be managed with appropriate supportive therapy. In addition to the adverse reactions listed above, the following adverse reactions have been described in the setting of ondansetron overdose: “Sudden blindness” (amaurosis) of 2 to 3 minutes’ duration plus severe constipation occurred in one patient that was administered 72 mg of ondansetron intravenously as a single dose. Hypotension (and faintness) occurred in a patient that took 48 mg of ondansetron tablets. …

Animal studies have shown that ondansetron is not discriminated as a benzodiazepine nor does it substitute for benzodiazepines in direct addiction studies.

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.