Dosage and administration

2 DOSAGE AND ADMINISTRATION •See full prescribing information for the recommended dosage in adults and pediatrics. (2) •Patients with severe hepatic impairment: do not exceed a total daily dose of 8 mg. (2.2, 8.6) 2.1 Dosage The recommended dosage regimens for adult and pediatric patients are described in Table 1 and Table 2, respectively. Corresponding doses of ZOFRAN tablets, ZOFRAN ODT® orally disintegrating tablets and ZOFRAN oral solution 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/m2 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. Postoperative 16 mg administered 1 hour before induction of anesthesia. Table 2: Pediatric Recommended Dosage Regimen for Prevention of Nausea and Vomiting Indication Dosage Regimen Moderately Emetogenic Cancer Chemotherapy 12 to 17 years of age: 8 mg administered 30 minutes before the start of chemotherapy, with a subsequent 8-mg dose 4 and 8 hours after the first dose. Then administer 8 mg three times a day for 1 to 2 days after completion of chemotherapy. 4 to 11 years of age: 4 mg administered 30 minutes before the start of chemotherapy, with a subsequent 4-mg dose 4 and 8 hours after the first dose. Then administer 4 mg three times a day for 1 to 2 days after completion of chemotherapy. 2.2 Dosage in Hepatic Impairment In patients with severe hepatic impairment (Child-Pugh score of 10 or greater), do not exceed a total daily dose of 8 mg [see Use in Specific Populations (8.6), Clinical Pharmacology (12.3)]. 2.3 Administration Instructions for ZOFRAN ODT Orally Disintegrating Tablets Do not attempt to push ZOFRAN ODT tablets through the foil backing. With dry hands, PEEL BACK the foil backing of 1 blister and GENTLY remove the tablet. IMMEDIATELY place the ZOFRAN ODT tablet on top of the tongue where it will dissolve in seconds, then swallow with saliva. Administration with liquid is not necessary.

Pregnancy

8.1 Pregnancy Risk Summary Available data do not reliably inform the association of ZOFRAN and adverse fetal outcomes. Published epidemiological studies on the association between ondansetron and fetal outcomes have reported inconsistent findings and have important methodological limitations hindering interpretation [see Data]. 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, respectively [see Data]. The background risk of major birth defects and miscarriage for the indicated population is unknown. 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 Methodological limitations of the epidemiology studies preclude a reliable evaluation of the potential risk of adverse fetal outcomes with the use of ondansetron in pregnancy. Two large retrospective cohort studies of ondansetron use in pregnancy have been published. In one study with 1,349 infants born to women who reported the use of ondansetron or received an ondansetron prescription in the first trimester, no increased risk for major congenital malformations was seen in aggregate analysis. In this same study, however, a sub-analysis for specific malformations reported an association between ondansetron exposure and cardiovascular defect (odds ratio (OR) 1.62 [95% CI (1.04, 2.14)]) and cardiac septal defect (OR 2.05 [95% CI (1.19, 3.28)]). The second study examined 1970 women who received ondansetron prescription during pregnancy and reported no association between ondansetron exposure and major congenital malformations, miscarriage or stillbirth, and infants of low birth weight or small for gestational age. Important methodological limitations with these studies include the uncertainty of whether women who filled a prescription actually took the medication, the concomitant use of other medications or treatments, and other unadjusted confounders that may account for the study findings. A case-control study evaluating associations between several common non-cardiac malformations and multiple antiemetic drugs reported an association between maternal use of ondansetron and isolated cleft palate (reported adjusted OR = 2.37 [95% CI (1.18, 4.76)]). However, this association could be a chance finding, given the large number of drugs-birth defect comparisons in this study. 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) or whether mothers of infants with cleft palate used other medications or had other risk factors for cleft palate in the offspring. In addition, no cases of isolated cleft palate were identified in the aforementioned two large retrospective cohort studies. At this time, there is no clear evidence that ondansetron exposure in early pregnancy can cause cleft palate. 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 maximum recommended human oral dose of 24 mg/day, respectively, based on body surface area. In a pre- and postnatal developmental toxicity study, pregnant rats received oral doses of ondansetron up to 15 mg/kg/day from Day 17 of pregnancy to litter Day 21. With the exception of a slight reduction in maternal body weight gain, there were no effects upon the pregnant rats and the pre- and postnatal development of their offspring, including reproductive performance of the mated F1 generation. At a dose of 15 mg/kg/day in rats, the maternal exposure margin was approximately 6 times the maximum recommended human oral dose of 24 mg/day, based on body surface area.

Drug Interactions

7 DRUG INTERACTIONS 7.1 Serotonergic Drugs Serotonin 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). Monitor for the emergence of serotonin syndrome. If symptoms occur, discontinue ZOFRAN 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)]. 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. 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 ZOFRAN is recommended for patients on these drugs [see Clinical Pharmacology (12.3)]. 7.3 Tramadol Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small trials indicate that when used together, ZOFRAN may increase patient-controlled administration of tramadol. Monitor patients to ensure adequate pain control when ondansetron is administered with tramadol. 7.4 Chemotherapy Carmustine, etoposide, and cisplatin do not affect the pharmacokinetics of ondansetron. In a crossover trial in 76 pediatric patients, intravenous ondansetron did not increase systemic concentrations of high-dose methotrexate. 7.5 Alfentanil and Atracurium ZOFRAN 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.

Indications And Usage

1 INDICATIONS AND USAGE ZOFRAN® is indicated for the prevention of nausea and vomiting associated with: •highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m2. •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. ZOFRAN is also indicated for the prevention of postoperative nausea and/or vomiting. ZOFRAN is a 5-HT3 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/m2. (1) •nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy. (1) •nausea and vomiting associated with radiotherapy in patients receiving either total body irradiation, single high-dose fraction to the abdomen, or daily fractions to the abdomen. (1) •postoperative nausea and/or vomiting. (1)

Clinical Studies

14 CLINICAL STUDIES 14.1 Prevention of Chemotherapy-induced Nausea and Vomiting Highly Emetogenic Chemotherapy In two randomized, double-blind, monotherapy trials, a single 24-mg oral dose of ZOFRAN was superior to a relevant historical placebo control in the prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m2. Steroid administration was excluded from these clinical trials. More than 90% of patients receiving a cisplatin dose greater than or equal to 50 mg/m2 in the historical placebo comparator experienced vomiting in the absence of antiemetic therapy. The first trial compared oral doses of ondansetron 24 mg as a single dose, 8 mg every 8 hours for 2 doses, and 32 mg as a single dose in 357 adult cancer patients receiving chemotherapy regimens containing cisplatin greater than or equal to 50 mg/m2. The first or single dose was administered 30 minutes prior to chemotherapy. A total of 66% of patients in the ondansetron 24-mg once-a-day group, 55% in the ondansetron 8‑mg twice-a-day group, and 55% in the ondansetron 32‑mg once-a-day group completed the 24-hour trial period with 0 emetic episodes and no rescue antiemetic medications, the primary endpoint of efficacy. Each of the 3 treatment groups was shown to be statistically significantly superior to a historical placebo control. In the same trial, 56% of patients receiving a single 24-mg oral dose of ondansetron experienced no nausea during the 24-hour trial period, compared with 36% of patients in the oral ondansetron 8‑mg twice-a-day group (P = 0.001) and 50% in the oral ondansetron 32-mg once-a-day group. Dosage regimens of ZOFRAN 8 mg twice daily and 32 mg once daily are not recommended for the prevention of nausea and vomiting associated with highly emetogenic chemotherapy [see Dosage and Administration (2.1)]. In a second trial, efficacy of a single 24-mg oral dose of ZOFRAN for the prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m2, was confirmed. Moderately Emetogenic Chemotherapy A randomized, placebo-controlled, double‑blind trial was conducted in the US in 67 patients receiving a cyclophosphamide‑based chemotherapy regimen containing doxorubicin. The first 8-mg dose of ZOFRAN was administered 30 minutes before the start of chemotherapy, with a subsequent dose 8 hours after the first dose, followed by 8 mg of ZOFRAN twice a day for 2 days after the completion of chemotherapy. ZOFRAN was significantly more effective than placebo in preventing vomiting. Treatment response was based on the total number of emetic episodes over the 3-day trial period. The results of this trial are summarized in Table 7: Table 7: Emetic Episodes: Treatment Response in Patients Receiving Moderately Emetogenic Chemotherapy (Cyclophosphamide-based Regimen Containing Doxorubicin) ZOFRAN (n = 33) Placebo (n = 34) P Value Treatment response 0 Emetic episodes 20 (61%) 2 (6%) <0.001 1 to 2 Emetic episodes 6 (18%) 8 (24%) More than 2 emetic episodes/withdrawn 7 (21%) 24 (71%) <0.001 Median number of emetic episodes 0.0 Undefineda Median time to first emetic episode (hours) Undefinedb 6.5 aMedian undefined since at least 50% of the patients were withdrawn or had more than 2 emetic episodes. bMedian undefined since at least 50% of patients did not have any emetic episodes. In a double‑blind US trial in 336 patients receiving a cyclophosphamide‑based chemotherapy regimen containing either methotrexate or doxorubicin, ZOFRAN 8 mg administered twice a day was as effective as ZOFRAN 8 mg administered 3 times a day in preventing nausea and vomiting. ZOFRAN 8 mg three times daily is not a recommended regimen for the treatment of moderately emetogenic chemotherapy [see Dosage and Administration (2.1)]. Treatment response was based on the total number of emetic episodes over the 3-day trial period. See Table 8 for the details of the dosage regimens studied and results of this trial. Table 8: Emetic Episodes: Treatment Response after ZOFRAN Tablets Administered Twice a Day and Three Times a Day ZOFRAN Tablets 8 mg Twice Dailya (n = 165) 8 mg Three Times a Dayb (n = 171) Treatment response 0 Emetic episodes 101 (61%) 99 (58%) 1-2 Emetic episodes 16 (10%) 17 (10%) More than 2 emetic episodes/withdrawn 48 (29%) 55 (32%) Median number of emetic episodes 0.0 0.0 Median time to first emetic episode (h) Undefinedc Undefinedc Median nausea scores (0-100)d 6 6 aThe first 8-mg dose was administered 30 minutes before the start of emetogenic chemotherapy, with a subsequent 8-mg dose 8 hours after the first dose, followed by 8 mg administered twice a day for 2 days after the completion of chemotherapy. bThe first 8-mg dose was administered 30 minutes before the start of emetogenic chemotherapy, with subsequent 8-mg doses at 4 hours and 8 hours after the first dose, followed by 8 mg administered 3 times a day for 2 days after the completion of chemotherapy. cMedian undefined since at least 50% of patients did not have any emetic episodes. dVisual analog scale assessment: 0 = no nausea, 100 = nausea as bad as it can be. Re‑treatment In single-arm trials, 148 patients receiving cyclophosphamide‑based chemotherapy were re‑treated with ZOFRAN 8 mg three times daily during subsequent chemotherapy for a total of 396 re‑treatment courses. No emetic episodes occurred in 314 (79%) of the re-treatment courses, and only 1 to 2 emetic episodes occurred in 43 (11%) of the re‑treatment courses. Pediatric Trials Three open‑label, single-arm, non-US trials have been performed with 182 pediatric patients aged 4 to 18 years with cancer who were given a variety of cisplatin or noncisplatin regimens. The initial dose of ZOFRAN injection ranged from 0.04 to 0.87 mg per kg (total dose of 2.16 mg to 12 mg) followed by the administration of oral doses of ZOFRAN ranging from 4 to 24 mg daily for 3 days. In these trials, 58% of the 170 evaluable patients had a complete response (no emetic episodes) on Day 1. In two trials the response rates to ZOFRAN 4 mg three times a day in patients younger than 12 years was similar to ZOFRAN 8 mg three times daily in patients 12 to 18 years. Prevention of emesis in these pediatric patients was essentially the same as for adults. 14.2 Radiation-induced Nausea and Vomiting Total Body Irradiation In a randomized, placebo-controlled, double‑blind trial in 20 patients, 8 mg of ZOFRAN administered 1.5 hours before each fraction of radiotherapy for 4 days was significantly more effective than placebo in preventing vomiting induced by total body irradiation. Total body irradiation consisted of 11 fractions (120 cGy per fraction) over 4 days for a total of 1,320 cGy. Patients received 3 fractions for 3 days, then 2 fractions on Day 4. Single High‑dose Fraction Radiotherapy In an active-controlled, double‑blind trial in 105 patients receiving single high‑dose radiotherapy (800 to 1,000 cGy) over an anterior or posterior field size of greater than or equal to 80 cm2 to the abdomen, ZOFRAN was significantly more effective than metoclopramide with respect to complete control of emesis (0 emetic episodes). Patients received the first dose of ZOFRAN (8 mg) or metoclopramide (10 mg) 1 to 2 hours before radiotherapy. If radiotherapy was given in the morning, 8 mg of ZOFRAN or 10 mg of metoclopramide was administered in the late afternoon and repeated again before bedtime. If radiotherapy was given in the afternoon, patients took 8 mg of ZOFRAN or 10 mg of metoclopramide only once before bedtime. Patients continued the doses of oral medication three times daily for 3 days. Daily Fractionated Radiotherapy In an active-controlled, double‑blind trial in 135 patients receiving a 1- to 4- week course of fractionated radiotherapy (180 cGy doses) over a field size of greater than or equal to 100 cm2 to the abdomen, ZOFRAN was significantly more effective than prochlorperazine with respect to complete control of emesis (0 emetic episodes). Patients received the first dose of ZOFRAN (8 mg) or prochlorperazine (10 mg) 1 to 2 hours before the first daily radiotherapy fraction, with subsequent 8-mg doses approximately every 8 hours on each day of radiotherapy. 14.3 Postoperative Nausea and Vomiting In two placebo-controlled, double-blind trials (one conducted in the US and the other outside the US) in 865 females undergoing inpatient surgical procedures, ZOFRAN 16 mg as a single dose or placebo was administered one hour before the induction of general balanced anesthesia (barbiturate, opioid, nitrous oxide, neuromuscular blockade, and supplemental isoflurane or enflurane), ZOFRAN tablets was significantly more effective than placebo in preventing postoperative nausea and vomiting. No trials have been performed in males.

Warnings And Cautions

5 WARNINGS AND PRECAUTIONS • Hypersensitivity reactions including anaphylaxis and bronchospasm: Discontinue ZOFRAN 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-HT3 receptor antagonists alone but particularly with concomitant use of serotonergic drugs. If such symptoms occur, discontinue ZOFRAN and initiate supportive treatment. If concomitant use of ZOFRAN with other serotonergic drugs is clinically warranted, patients should be made aware of a potential increased risk for serotonin syndrome. (5.3) • Masking of progressive ileus and/or gastric distention following abdominal surgery or chemotherapy-induced nausea and vomiting: Monitor for decreased bowel activity, particularly in patients with risk factors for gastrointestinal obstruction. (5.4) •Phenylketonuric patients should be informed that ZOFRAN ODT orally disintegrating tablets contain phenylalanine (a component of aspartame). Each 4-mg and 8-mg orally disintegrating tablet contains less than 0.03 mg phenylalanine. (5.5) 5.1 Hypersensitivity Reactions Hypersensitivity reactions, including anaphylaxis and bronchospasm, have been reported in patients who have exhibited hypersensitivity to other selective 5-HT3 receptor antagonists. If hypersensitivity reactions occur, discontinue use of ZOFRAN; treat promptly per standard of care and monitor until signs and symptoms resolve [see Contraindications (4)]. 5.2 QT Prolongation Electrocardiogram (ECG) changes including QT interval prolongation have been seen in patients receiving ondansetron. In addition, postmarketing cases of Torsade de Pointes have been reported in patients using ZOFRAN. Avoid ZOFRAN in patients with congenital long QT syndrome. ECG monitoring is recommended in patients with electrolyte abnormalities (e.g., hypokalemia or hypomagnesemia), congestive heart failure, bradyarrhythmias, or patients taking other medicinal products that lead to QT prolongation [see Clinical Pharmacology (12.2)]. 5.3 Serotonin Syndrome The development of serotonin syndrome has been reported with 5-HT3 receptor antagonists alone. Most reports have been associated with concomitant use of serotonergic drugs (e.g., selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors, mirtazapine, fentanyl, lithium, tramadol, and intravenous methylene blue). Some of the reported cases were fatal. Serotonin syndrome occurring with overdose of ZOFRAN alone has also been reported. The majority of reports of serotonin syndrome related to 5-HT3 receptor antagonist use occurred in a post-anesthesia care unit or an infusion center. Symptoms associated with serotonin syndrome may include the following combination of signs and symptoms: mental status changes (e.g., agitation, hallucinations, delirium, and coma), autonomic instability (e.g., tachycardia, labile blood pressure, dizziness, diaphoresis, flushing, hyperthermia), neuromuscular symptoms (e.g., tremor, rigidity, myoclonus, hyperreflexia, incoordination), seizures, with or without gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea). Patients should be monitored for the emergence of serotonin syndrome, especially with concomitant use of ZOFRAN and other serotonergic drugs. If symptoms of serotonin syndrome occur, discontinue ZOFRAN and initiate supportive treatment. Patients should be informed of the increased risk of serotonin syndrome, especially if ZOFRAN is used concomitantly with other serotonergic drugs [see Drug Interactions (7.1), Overdosage (10)]. 5.4 Masking of Progressive Ileus and Gastric Distension The use of ZOFRAN in patients following abdominal surgery or in patients with chemotherapy‑induced nausea and vomiting may mask a progressive ileus and/or gastric distension. Monitor for decreased bowel activity, particularly in patients with risk factors for gastrointestinal obstruction. ZOFRAN is not a drug that stimulates gastric or intestinal peristalsis. It should not be used instead of nasogastric suction. 5.5 Phenylketonuria Phenylketonuric patients should be informed that ZOFRAN ODT orally disintegrating tablets contain phenylalanine (a component of aspartame). Each 4-mg and 8-mg orally disintegrating tablet contains less than 0.03 mg phenylalanine.

Overdosage

Adverse Reactions

Mechanism

Contraindications