Ondansetron Hydrochloride

Warnings and Precautions, Myocardial Ischemia ( 5.4 ) 10/2021

1 INDICATIONS AND USAGE Ondansetron injection is a 5-HT 3 receptor antagonist indicated for the prevention of: • nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy. ( 1.1 ) • postoperative nausea and/or vomiting. ( 1.2 ) 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. Ondansetron injection 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. Ondansetron injection is approved for patients aged 1 month and older.

2 DOSAGE AND ADMINISTRATION Prevention of Nausea and Vomiting Associated With Initial and Repeat Courses of Emetogenic Cancer Chemotherapy ( 2.1 ): • Dilution of ondansetron injection in 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection is required before administration to adult and pediatric patients. • Adults and pediatric patients 6 months of age and older: The recommended dosage is 0.15 mg/kg per dose for 3 doses (maximum of 16 mg per dose), infused intravenously over 15 minutes. • Administer the first dose 30 minutes before the start of chemotherapy and subsequent doses 4 and 8 hours after the first dose. Prevention of Postoperative Nausea and/or Vomiting ( 2.2 ): • Dilution of ondansetron injection is not required before administration to adult and pediatric patients. • See full prescribing information for the recommended dosage and administration instructions for adult and pediatric patients 1 month of age and older. Patients With Severe Hepatic Impairment ( 2.3 ): • Do not exceed a total daily dose of 8 mg. 2.1 Prevention of Nausea and Vomiting Associated With Initial and Repeat Courses of Emetogenic Chemotherapy Important Preparation Instructions • Dilution of ondansetron injection in 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection is required before administration to adult and pediatric patients for the prevention of nausea and vomiting associated with emetogenic chemotherapy. For pediatric patients between 6 months and 1 year of age and/or 10 kg or less : Depending on the fluid needs of the patient, ondansetron injection may be diluted in 10 to 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection. • 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. • Do not mix ondansetron injection with solutions for which physical and chemical compatibility has not been established. In particular, this applies to alkaline solutions as a precipitate may form. • Inspect the diluted ondansetron injection solution for particulate matter and discoloration before administration; discard if present. • Storage: 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. • Compatibility : Ondansetron injection is compatible and 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. Dosage and Administration The recommended dosage for adult and pediatric patients 6 months of age and older for prevention of nausea and vomiting associated with emetogenic chemotherapy is 0.15‐mg/kg per dose for 3 doses (maximum of 16 mg per dose). Caution: Dilution of ondansetron injection is required in adult and pediatric patients prior to administration. Infuse intravenously over 15 minutes beginning 30 minutes before the start of emetogenic chemotherapy and then repeat 4 and 8 hours after the first dose. 2.2 Prevention of Postoperative Nausea and/or Vomiting Important Preparation Instructions • Dilution of ondansetron injection is not required before administration to adult and pediatric patients. • Inspect ondansetron injection visually for particulate matter and discoloration before administration; discard if present. Dosage and Administration The recommended dose and administration instructions for adult and pediatric patients 1 month of age and older for prevention of postoperative nausea and vomiting are shown in Table 1. Table 1. Recommended Dose and Administration of Ondansetron Injection for Prevention of Postoperative Nausea a …

3 DOSAGE FORMS AND STRENGTHS Ondansetron Oral Solution, USP, 4 mg/5 mL, is a clear, colorless liquid with a characteristic strawberry odor available in a brown, 50-mL bottle and 5 mL unit dose cups in trays of 20 cups. Oral Solution: 4 mg/5 mL. ( 3 )

4 CONTRAINDICATIONS 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. • Patients known to have hypersensitivity (e.g., anaphylaxis) to this product or any of its components. ( 4 ) • Concomitant use of apomorphine. ( 4 , 7.2 )

6 ADVERSE REACTIONS 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) ] Chemotherapy-Induced Nausea and Vomiting: • The most common adverse reactions (≥ 7%) in adults are diarrhea, headache, and fever. ( 6.1 ) Postoperative Nausea and/or Vomiting: • The most common adverse reaction (≥ 10%) which occurs at a higher frequency compared with placebo in adults is headache. ( 6.1 ) • The most common adverse reaction (≥ 2%) which occurs at a higher frequency compared with placebo in pediatric patients aged 1 to 24 months is diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Baxter Healthcare Corporation at 1-877-725-2747 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 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 with 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 injection across a range of dosages. A causal relationship to therapy with ondansetron injection (ondansetron) was unclear in many cases. Chemotherapy-Induced Nausea and Vomiting Table 2. Adverse Reactions Reported in > 5% of Adult Patients Who Received Ondansetron at a Dosage of Three 0.15-mg/kg Doses Adverse Reaction Number of Adult Patients With Reaction Ondansetron Injection 0.15 mg/kg x 3 (n = 419) Metoclopramide (n = 156) Placebo (n = 34) Diarrhea 16% 44% 18% Headache 17% 7% 15% Fever 8% 5% 3% 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/or Vomiting The adverse reactions in Table 3 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 3. 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 Adverse Reaction 1,2 Ondansetron Injection 4 mg Intravenous (n = 547) Placebo (n = 547) Headache 92 (17%) 77 (14%) Drowsiness/Sedation 44 (8%) 37 (7%) Injection-site reaction 21 (4%) 18 (3%) Fever 10 (2%) 6 (1%) Cold sensation 9 (2%) 8 (1%) Pruritus 9 (2%) 3 (< 1%) Paresthesia 9 (2%) 2 (< 1%) 1. Adverse reactions: Rates of these reactions were not significantly different in the ondansetron and placebo groups. 2. Patients were receiving multiple concomitant perioperative and postoperati …

7 DRUG INTERACTIONS 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 trials 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 trials, leading to an increased cumulative dose in patient-controlled administration of tramadol. 7.5 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 [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 trial in 76 pediatric patients, intravenous ondansetron did not increase blood levels of high-dose methotrexate. 7.7 Temazepam The co-administration 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.

8 USE IN SPECIFIC POPULATIONS 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. Reproductive studies in rats and rabbits did not show evidence of harm to the fetus when ondansetron was administered during organogenesis at approximately 6 and 24 times the maximum recommended human oral dose of 24 mg/day, based on body surface area (BSA), respectively (see Data ) . The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, miscarriages, or other adverse outcomes. In the US general population, the estimated background risk of major birth defects and miscarriages in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Human Data Available data on ondansetron use in pregnant women from several published epidemiological studies preclude an assessment of a drug-associated risk of adverse fetal outcomes due to important methodological limitations, including the uncertainty of whether women who filled a prescription actually took the medication, the concomitant use of other medications or treatments, recall bias, and other unadjusted confounders. Ondansetron exposure in utero has not been associated with overall major congenital malformations in aggregate analyses. One large retrospective cohort study examined 1970 women who received a prescription for ondansetron during pregnancy and reported no association between ondansetron exposure and major congenital malformations, miscarriage, stillbirth, preterm delivery, infants of low birth weight, or infants small for gestational age. Two large retrospective cohort studies and one case-control study have assessed ondansetron exposure in the first trimester and risk of cardiovascular defects with inconsistent findings. Relative risks (RR) ranged from 0.97 (95% CI 0.86 to 1.10) to 1.62 (95% CI 1.04, 2.54). A subset analysis in one of the cohort studies observed that ondansetron was specifically associated with cardiac septal defects (RR 2.05, 95% CI 1.19, 3.28); however, this association was not confirmed in other studies. Several studies have assessed ondansetron and the risk of oral clefts with inconsistent findings. A retrospective cohort study of 1.8 million pregnancies in the US Medicaid Database showed an increased risk of oral clefts among 88,467 pregnancies in which oral ondansetron was prescribed in the first trimester (RR 1.24, 95% CI 1.03, 1.48), but no such association was reported with intravenous ondansetron in 23,866 pregnancies (RR 0.95, 95% CI 0.63, 1.43). In the subgroup of women who received both forms of administration, the RR was 1.07 (95% CI 0.59, 1.93). Two case-control studies, using data from birth defects surveillance programs, reported conflicting associations between maternal use of ondansetron and isolated cleft palate (OR 1.6 [95% CI 1.1, 2.3] and 0.5 [95% CI 0.3, 1.0]). It is unknown whether ondansetron exposure in utero in the cases of cleft palate occurred during the time of palate formation (the palate is formed between the 6th and 9th weeks of pregnancy). Animal Data In embryo-fetal development studies in rats and rabbits, pregnant animals received oral doses of ondansetron up to 15 mg/kg/day and 30 mg/kg/day, respectively, during the period of organogenesis. With the exception of a slight decrease in maternal body weight gain in the rabbits, there were no significant effects of ondansetron on the maternal animals or the development of the offspring. At doses of 15 mg/kg/day in rats and 30 mg/kg/day in rabbits, the maternal exposure margin was approximately 6 and 24 times the …

12.1 Mechanism of Action Ondansetron is a selective 5-HT 3 receptor antagonist. While its mechanism of action has not been fully characterized, ondansetron is not a dopamine-receptor antagonist. Serotonin receptors of the 5-HT 3 type are present both peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone of the area postrema. It is not certain whether ondansetron's antiemetic action is mediated centrally, peripherally, or in both sites. However, cytotoxic chemotherapy appears to be associated with release of serotonin from the enterochromaffin cells of the small intestine. In humans, urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion increases after cisplatin administration in parallel with the onset of emesis. The released serotonin may stimulate the vagal afferents through the 5-HT 3 receptors and initiate the vomiting reflex.

11 DESCRIPTION The active ingredient of ondansetron injection, USP is ondansetron hydrochloride, a selective blocking agent of the serotonin 5-HT 3 receptor type. Its chemical name 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: The empirical formula is C 18 H 19 N 3 O•HCl•2H 2 O, representing a molecular weight of 365.9 g/mol. Ondansetron HCl is a white to off-white powder that is soluble in water and normal saline. Each 1 mL of aqueous solution in the 2 mL single-dose vial contains 2 mg of ondansetron as the hydrochloride dihydrate; 9 mg of sodium chloride, USP; and 0.5 mg of citric acid monohydrate, USP and 0.25 mg of sodium citrate dihydrate, USP as buffers in Water for Injection, USP. Ondansetron injection, USP is a clear, colorless, nonpyrogenic, sterile solution for intravenous use. The pH of the injection solution is 3.3 to 4.0. Structural Formula

10 OVERDOSAGE There is no specific antidote for ondansetron overdose. Patients should be managed with appropriate supportive therapy. Individual intravenous doses as large as 150 mg and total daily intravenous doses as large as 252 mg have been inadvertently administered without significant adverse events. These doses are more than 10 times the recommended daily dose. In addition to the adverse reactions listed above, the following events 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 another patient that took 48 mg of ondansetron hydrochloride tablets. Following infusion of 32 mg over only a 4-minute period, a vasovagal episode with transient second-degree heart block was observed. In all instances, the events resolved completely. Pediatric cases consistent with serotonin syndrome have been reported after inadvertent oral overdoses of ondansetron (exceeding estimated ingestion of 5 mg/kg) in young children. Reported symptoms included somnolence, agitation, tachycardia, tachypnea, hypertension, flushing, mydriasis, diaphoresis, myoclonic movements, horizontal nystagmus, hyperreflexia, and seizure. Patients required supportive care, including intubation in some cases, with complete recovery without sequelae within 1 to 2 days.

16 HOW SUPPLIED/STORAGE AND HANDLING Ondansetron Oral Solution, USP a clear, colorless liquid with a characteristic strawberry odor, contains 5 mg of ondansetron hydrochloride dihydrate equivalent to 4 mg of ondansetron per 5 mL in brown bottles of 50 mL (NDC 62135-555-58) with child-resistant closures, unit dose cup 5 mL (NDC 62135-555-45) and 20 unit dose cups of 5 mL each (NDC 62135-555-24). Store at 20° to 25°C (68° to 77°F), [See USP Controlled Room Temperature]. Protect from light. Store bottles upright in cartons.