ONDANSETRON

The active ingredient of Ondansetron Injection, USP is ondansetron hydrochloride, the racemic form of ondansetron and a selective blocking agent of the serotonin 5-HT3 receptor type. Chemically it is (±) 1, 2, 3, 9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one, monohydrochloride dihydrate. It has the following structural formula: Ondansetron is a white to off-white powder that is sparingly soluble in water. Each mL of the preservative-free aqueous solution in the 2 mL single use vial contains 2 mg of ondansetron as the hydrochloride; 9 mg of sodium chloride; and 0.5 mg of citric acid monohydrate and 0.25 mg of sodium citrate dihydrate as buffers in water for injection. Each mL of the preserved aqueous solution in the 20 mL multiple dose vial contains 2 mg of ondansetron as the hydrochloride; 8.3 mg of sodium chloride; 0.5 mg of citric acid monohydrate and 0.25 mg of sodium citrate dihydrate as buffers; and 1.2 mg of methylparaben and 0.15 mg of propylparaben as preservatives in water for injection. Ondansetron Injection is a clear, colorless, nonpyrogenic, sterile solution for intravenous use. The pH of the injection solution is 3.3 to 4.0. STRUCTURE

INDICATIONS & USAGE 1.1 Prevention of Nausea and Vomiting Associated with Initial and Repeat Courses of Emetogenic Cancer Chemotherapy Ondansetron injection is indicated for the prevention of nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy, including high-dose cisplatin [see CLINICAL STUDIES (14.1)]. Ondansetron is approved for patients aged 6 months and older. 1.2 Prevention of Postoperative Nausea and/or Vomiting Ondansetron injection is indicated for the prevention of postoperative nausea and/or vomiting. As with other antiemetics, routine prophylaxis is not recommended for patients in whom there is little expectation that nausea and/or vomiting will occur postoperatively. In patients in whom nausea and/or vomiting must be avoided postoperatively, ondansetron injection is recommended even when the incidence of postoperative nausea and/or vomiting is low. For patients who do not receive prophylactic ondansetron injection and experience nausea and/or vomiting postoperatively, ondansetron injection may be given to prevent further episodes [see CLINICAL STUDIES (14.3)]. Ondansetron is approved for patients aged 1 month and older.

2.1 Prevention of Nausea and Vomiting Associated with Initial and Repeat Courses of Emetogenic Chemotherapy Ondansetron injection should be diluted in 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection before administration. Adults: The recommended adult intravenous dosage of ondansetron is three 0.15 mg/kg doses up to a maximum of 16 mg per dose [see CLINICAL PHARMACOLOGY (12.2)]. The first dose is infused over 15 minutes beginning 30 minutes before the start of emetogenic chemotherapy. Subsequent doses (0.15 mg/kg up to a maximum of 16 mg per dose) are administered 4 and 8 hours after the first dose of ondansetron. Pediatrics: For pediatric patients 6 months through 18 years of age, the intravenous dosage of ondansetron is three 0.15 mg/kg doses up to a maximum of 16 mg per dose [see CLINICAL STUDIES (14.1) and CLINICAL PHARMACOLOGY (12.2, 12.3)]. The first dose is to be administered 30 minutes before the start of moderately to highly emetogenic chemotherapy. Subsequent doses (0.15 mg/kg up to a maximum of 16 mg per dose) are administered 4 and 8 hours after the first dose of ondansetron. The drug should be infused intravenously over 15 minutes. 2.2 Prevention of Postoperative Nausea and Vomiting Ondansetron injection should not be mixed with solutions for which physical and chemical compatibility have not been established. In particular, this applies to alkaline solutions as a precipitate may form. Adults: The recommended adult intravenous dosage of ondansetron is 4 mg undiluted administered intravenously in not less than 30 seconds, preferably over 2 to 5 minutes, immediately before induction of anesthesia, or postoperatively if the patient did not receive prophylactic antiemetics and experiences nausea and/or vomiting occurring within 2 hours after surgery. Alternatively, 4 mg undiluted may be administered intramuscularly as a single injection for adults. While recommended as a fixed dose for patients weighing more than 40 kg, few patients above 80 kg have been studied. In patients who do not achieve adequate control of postoperative nausea and vomiting following a single, prophylactic, preinduction, intravenous dose of ondansetron 4 mg, administration of a second intravenous dose of 4 mg ondansetron postoperatively does not provide additional control of nausea and vomiting. Pediatrics: For pediatric patients 1 month through 12 years of age, the dosage is a single 0.1 mg/kg dose for patients weighing 40 kg or less, or a single 4 mg dose for patients weighing more than 40 kg. The rate of administration should not be less than 30 seconds, preferably over 2 to 5 minutes immediately prior to or following anesthesia induction, or postoperatively if the patient did not receive prophylactic antiemetics and experiences nausea and/or vomiting occurring shortly after surgery. Prevention of further nausea and vomiting was only studied in patients who had not received prophylactic ondansetron. 2.3 Stability and Handling After dilution, do not use beyond 24 hours. Although ondansetron injection is chemically and physically stable when diluted as recommended, sterile precautions should be observed because diluents generally do not contain preservative. Ondansetron injection is stable at room temperature under normal lighting conditions for 48 hours after dilution with the following intravenous fluids: 0.9% Sodium Chloride Injection, 5% Dextrose Injection, 5% Dextrose and 0.9% Sodium Chloride Injection, 5% Dextrose and 0.45% Sodium Chloride Injection, and 3% Sodium Chloride Injection. Note: Parenteral drug products should be inspected visually for particulate matter and discoloration before administration whenever solution and container permit. Precaution: Occasionally, ondansetron precipitates at the stopper/vial interface in vials stored upright. Potency and safety are not affected. If a precipitate is observed, resolubilize by shaking the vial vigorously. 2.4 Dosage Adjustment for Patients with Impaired Hepatic Function In patients with severe hepatic impairment (Child-Pugh score of 10 or greater), a single maximal daily dose of 8 mg infused over 15 minutes beginning 30 minutes before the start of the emetogenic chemotherapy is recommended. There is no experience beyond first-day administration of ondansetron in these patients [see CLINICAL PHARMACOLOGY (12.3)].

Ondansetron injection is contraindicated for patients known to have hypersensitivity (e.g., anaphylaxis) to this product or any of its components. Anaphylactic reactions have been reported in patients taking ondansetron [see ADVERSE REACTIONS (6.2)]. The concomitant use of apomorphine with ondansetron is contraindicated based on reports of profound hypotension and loss of consciousness when apomorphine was administered with ondansetron.

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. The following adverse reactions have been reported in clinical trials of adult patients treated with ondansetron, the active ingredient of intravenous ondansetron across a range of dosages. A causal relationship to therapy with ondansetron was unclear in many cases. Chemotherapy-Induced Nausea and Vomiting: Table 1: Adverse Reactions Reported in > 5% of Adult Patients Who Received Ondansetron at a Dosage of Three 0.15 mg/kg Doses Cardiovascular: Rare cases of angina (chest pain), electrocardiographic alterations, hypotension, and tachycardia have been reported. Gastrointestinal: Constipation has been reported in 11% of chemotherapy patients receiving multiday ondansetron. Hepatic: In comparative trials in cisplatin chemotherapy patients with normal baseline values of aspartate transaminase (AST) and alanine transaminase (ALT), these enzymes have been reported to exceed twice the upper limit of normal in approximately 5% of patients. The increases were transient and did not appear to be related to dose or duration of therapy. On repeat exposure, similar transient elevations in transaminase values occurred in some courses, but symptomatic hepatic disease did not occur. Integumentary: Rash has occurred in approximately 1% of patients receiving ondansetron. Neurological: There have been rare reports consistent with, but not diagnostic of, extrapyramidal reactions in patients receiving ondansetron injection, and rare cases of grand mal seizure. Other: Rare cases of hypokalemia have been reported. Postoperative Nausea and Vomiting: The adverse reactions in Table 2 have been reported in ≥ 2% of adults receiving ondansetron at a dosage of 4 mg intravenous over 2 to 5 minutes in clinical trials. Table 2: Adverse Reactions Reported in ≥ 2% (and with Greater Frequency than the Placebo Group) of Adult Patients Receiving Ondansetron at a Dosage of 4 mg Intravenous over 2 to 5 Minutes a Adverse Reactions: Rates of these reactions were not significantly different in the ondansetron and placebo groups b Patients were receiving multiple concomitant perioperative and postoperative medications Pediatric Use: Rates of adverse reactions were similar in both the ondansetron and placebo groups in pediatric patients receiving ondansetron (a single 0.1 mg/kg dose for pediatric patients weighing 40 kg or less, or 4 mg for pediatric patients weighing more than 40 kg) administered intravenously over at least 30 seconds. Diarrhea was seen more frequently in patients taking ondansetron (2%) compared to placebo (< 1%) in the 1 month to 24 month age group. These patients were receiving multiple concomitant perioperative and postoperative medications. 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of ondansetron. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The reactions have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to ondansetron. Cardiovascular: Arrhythmias (including ventricular and supraventricular tachycardia, premature ventricular contractions, and atrial fibrillation), bradycardia, electrocardiographic alterations (including second-degree heart block, QT/QTc interval prolongation, and ST segment depression), palpitations, and syncope. Rarely and predominantly with intravenous ondansetron, transient ECG changes including QT/QTc interval prolongation have been reported [see WARNINGS AND PRECAUTIONS (5.2)]. General: Flushing. Rare cases of hypersensitivity reactions, sometimes severe (e.g., anaphylactic reactions, angioedema, bronchospasm, cardiopulmonary arrest, hypotension, laryngeal edema, laryngospasm, shock, shortness of breath, stridor) have also been reported. A positive lymphocyte transformation test to ondansetron has been reported, which suggests immunologic sensitivity to ondansetron. Hepatobiliary: Liver enzyme abnormalities have been reported. Liver failure and death have been reported in patients with cancer receiving concurrent medications including potentially hepatotoxic cytotoxic chemotherapy and antibiotics. Local Reactions: Pain, redness, and burning at site of injection. Lower Respiratory: Hiccups. Neurological: Oculogyric crisis, appearing alone, as well as with other dystonic reactions. Transient dizziness during or shortly after intravenous infusion. Skin: Urticaria, Stevens-Johnson syndrome, and toxic epidermal necrolysis. Eye Disorders: Cases of transient blindness, predominantly during intravenous administration, have been reported. These cases of transient blindness were reported to resolve within a few minutes up to 48 hours. Transient blurred vision, in some cases associated with abnormalities of accommodation, have also been reported. ADVERSE 1 ADVERSE 2

7.1 Drugs Affecting Cytochrome P-450 Enzymes Ondansetron does not appear to induce or inhibit the cytochrome P-450 drug-metabolizing enzyme system of the liver. Because ondansetron is metabolized by hepatic cytochrome P-450 drug-metabolizing enzymes (CYP3A4, CYP2D6, CYP1A2), inducers or inhibitors of these enzymes may change the clearance and, hence, the half-life of ondansetron [see CLINICAL PHARMACOLOGY (12.3)]. On the basis of limited available data, no dosage adjustment is recommended for patients on these drugs. 7.2 Apomorphine Based on reports of profound hypotension and loss of consciousness when apomorphine was administered with ondansetron, the concomitant use of apomorphine with ondansetron is contraindicated [see CONTRAINDICATIONS (4)]. 7.3 Phenytoin, Carbamazepine, and Rifampin In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased. However, on the basis of available data, no dosage adjustment for ondansetron is recommended for patients on these drugs [see CLINICAL PHARMACOLOGY (12.3)]. 7.4 Tramadol Although there are no data on pharmacokinetic drug interactions between ondansetron and tramadol, data from two small studies indicate that concomitant use of ondansetron may result in reduced analgesic activity of tramadol. Patients on concomitant ondansetron self administered tramadol more frequently in these studies, leading to an increased cumulative dose in patient controlled administration (PCA) of tramadol. 7.5 Serotonergic Drugs Serotinin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has been described following the concomitant use of 5-HT3 receptor antagonists and other serotonergic drugs, including selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs) [see WARNINGS AND PRECAUTIONS (5.3)]. 7.6 Chemotherapy In humans, carmustine, etoposide, and cisplatin do not affect the pharmacokinetics of ondansetron. In a crossover study in 76 pediatric patients, intravenous ondansetron did not increase blood levels of high-dose methotrexate. 7.7 Temazepam The coadministration of ondansetron had no effect on the pharmacokinetics and pharmacodynamics of temazepam. 7.8 Alfentanil and Atracurium Ondansetron does not alter the respiratory depressant effects produced by alfentanil or the degree of neuromuscular blockade produced by atracurium. Interactions with general or local anesthetics have not been studied.