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SILARX/LANNETT
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54838055550

ondansetron 4 mg/5 ml solution (generic zofran)

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Uses

Cancer Chemotherapy-induced Nausea and Vomiting

Ondansetron is used orally or IV for the prevention of nausea and vomiting associated with emetogenic cancer chemotherapy. The drug is used IV with initial and repeat courses of emetogenic cancer chemotherapy, including high-dose cisplatin therapy. Ondansetron is used orally with highly emetogenic cancer chemotherapy (including cisplatin at a dosage of 50 mg/m or greater). Ondansetron also is used orally with initial and repeat courses of moderately emetogenic cancer chemotherapy. The drug has been used effectively for the prevention of chemotherapy-induced emesis in patients receiving cisplatin alone or in combination with other antineoplastic agents and in those receiving other antineoplastic regimens (e.g., cyclophosphamide plus fluorouracil, doxorubicin, methotrexate, and/or vincristine) that did not include cisplatin.

To prevent chemotherapy-induced nausea and vomiting associated with highly emetogenic chemotherapy regimens (including an anthracycline plus cyclophosphamide), the American Society of Clinical Oncology (ASCO) currently recommends a 3-drug antiemetic regimen consisting of a neurokinin-1 (NK1) receptor antagonist (e.g., either oral aprepitant or IV fosaprepitant dimeglumine), a type 3 serotonin (5-HT3) receptor antagonist (e.g., dolasetron, granisetron, ondansetron, palonosetron, ramosetron [not commercially available in the US], tropisetron [not commercially available in the US]), and dexamethasone. ASCO states that the oral, fixed-combination of netupitant and palonosetron plus dexamethasone is an additional antiemetic treatment option in this setting.

For patients receiving moderately emetogenic chemotherapy regimens, ASCO recommends a 2-drug antiemetic regimen preferably consisting of palonosetron and dexamethasone. If palonosetron is not available, a first-generation 5-HT3 receptor antagonist (preferably granisetron or ondansetron) may be substituted. Limited evidence suggests that aprepitant may be added to this regimen; in such cases, ASCO states that any of the 5-HT3 receptor antagonists is appropriate.

For patients receiving chemotherapy regimens with a low emetogenic risk, ASCO recommends administration of a single dose of dexamethasone prior to chemotherapy.

In patients receiving chemotherapy regimens with a minimal emetogenic risk, antiemetics should not be routinely administered prior to or following chemotherapy.

Postoperative Nausea and Vomiting

Ondansetron is used orally or IV for the prevention of postoperative nausea and vomiting. Oral or IV ondansetron has been used effectively to prevent nausea and vomiting in surgical patients where nausea and vomiting must be avoided postoperatively; IV ondansetron also has been used effectively to prevent further episodes of nausea and vomiting in patients who did not receive prophylactic antiemetic therapy and developed postoperative nausea and/or vomiting. Studies of oral ondansetron for the prevention of postoperative nausea and vomiting to date have included only women undergoing inpatient surgical procedures; no studies have been performed in males. Controlled studies comparing oral versus IV administration of ondansetron have not been performed to date. The manufacturer states that as with other antiemetics, routine prophylaxis with ondansetron is not recommended in patients in whom there is little expectation that nausea and/or vomiting will occur postoperatively. However, use of the drug is recommended for patients in whom nausea and/or vomiting must be avoided postoperatively, even when the anticipated incidence of such nausea and/or vomiting is low.

Radiation-induced Nausea and Vomiting

Ondansetron is used orally for the prevention of radiation-induced nausea and vomiting. The drug has been used effectively to prevent nausea and vomiting in patients receiving total body irradiation or single high-dose fraction or daily fractionated radiation to the abdomen.

Dosage and Administration

Reconstitution and Administration

Ondansetron hydrochloride generally is administered orally or IV; the manufacturer states that, alternatively, the drug may be administered undiluted by IM injection in adults for prevention of postoperative nausea and vomiting.(See Dosage: Postoperative Nausea and Vomiting.) For prevention of cancer chemotherapy-induced nausea and vomiting, ondansetron hydrochloride injection should be diluted in 50 mL of 5% dextrose injection or 0.9% sodium chloride injection and infused IV over 15 minutes.

For prevention of postoperative nausea and vomiting, ondansetron hydrochloride injection in single- or multiple-dose vials does not require dilution. The undiluted drug is administered by IV injection over a period of at least 30 seconds and, preferably, over a period of 2-5 minutes.

Ondansetron hydrochloride occasionally precipitates at the stopper/vial interface in vials that are stored upright; the manufacturer states that potency and safety of the drug are not affected. If a precipitate is found, the drug may be resolubilized by vigorous shaking of the vial.

Patients receiving ondansetron orally disintegrating tablets should be instructed not to remove a tablet from the blister until just prior to dosing. The tablet should not be pushed through the foil. With dry hands, the blister backing should be peeled completely off the blister. The tablet should then be gently removed and immediately placed on the tongue to dissolve and be swallowed with the saliva; administration with liquid is not necessary.

Dosage

Dosage of ondansetron, which is available for oral or IV use as the hydrochloride dihydrate and also for oral use as ondansetron base (orally disintegrating tablets), is expressed in terms of ondansetron.

Cancer Chemotherapy-induced Nausea and Vomiting

Oral Dosage

For the prevention of nausea and vomiting associated with moderately emetogenic cancer chemotherapy in adults and children 12 years of age and older, an initial ondansetron dose of 8 mg is given 30 minutes before administration of an emetogenic drug and the dose is repeated 8 hours after the initial dose. An 8-mg dose should be administered at 12-hour intervals for 1-2 days following completion of the emetogenic chemotherapy.

For children 4-11 years of age, an initial ondansetron dose of 4 mg is given 30 minutes before administration of a moderately emetogenic cancer chemotherapy drug, with subsequent doses 4 and 8 hours after the initial dose. A 4-mg dose should then be administered at 8-hour intervals for 1-2 days following completion of emetogenic cancer chemotherapy. Little information currently is available regarding dosages for children younger than 4 years of age.

For the prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy in adults, a single oral 24-mg dose of ondansetron is given 30 minutes before administration of single-day chemotherapy. The manufacturer states that multiple-day, single-daily-dose oral administration of ondansetron 24 mg has not been studied to date. In addition, safety and efficacy of single-daily-dose oral administration of the 24-mg dose have not been established in pediatric patients.

The manufacturer states that dosage modification is not necessary in geriatric patients.

IV Dosage

For the prevention of cancer chemotherapy-induced nausea and vomiting in adults and pediatric patients 6 months of age and older, an initial IV ondansetron dose of 0.15 mg/kg (up to a maximum of 16 mg per dose) is given as a 15-minute infusion beginning 30 minutes before administration of an emetogenic drug and is repeated twice at 4-hour intervals following the initial dose. Because of the risk of QT interval prolongation (see Cautions: Cardiovascular Effects), an antiemetic regimen consisting of a single IV ondansetron dose of 32 mg no longer is recommended for prevention of cancer chemotherapy-induced nausea and vomiting. Efficacy and safety of alternative single-dose IV ondansetron regimens for prevention of cancer chemotherapy-induced nausea and vomiting have not been established.

The manufacturer states that dosage modification is not necessary in geriatric patients. Little information currently is available regarding dosages for pediatric patients younger than 6 months of age.

Postoperative Nausea and Vomiting

For the prevention of postoperative nausea and vomiting in adults, a single ondansetron IV dose of 4 mg is given immediately before induction of anesthesia or postoperatively if the patient experiences nausea and/or vomiting shortly after surgery. In pediatric patients 1 month to 12 years of age, the recommended dosage of ondansetron is a single IV dose of 4 mg in patients weighing more than 40 kg or a single IV dose of 0.1 mg/kg in patients weighing 40 kg or less; the dose should be given immediately before or after induction of anesthesia or postoperatively if the patient experiences nausea and/or vomiting shortly after surgery. Little information is available regarding dosages for patients weighing more than 80 kg. The manufacturer states that adults who do not achieve adequate control of postoperative nausea and vomiting with a single 4-mg IV dose of ondansetron given prior to induction of anesthesia will not obtain additional benefit from administration of a second 4-mg dose of the drug postoperatively. Efficacy of a second dose of ondansetron in pediatric patients who did not achieve adequate control of postoperative nausea and vomiting following a single prophylactic dose of the drug has not been evaluated.

If ondansetron is used orally for the prevention of postoperative nausea and vomiting in adults, a single 16-mg dose is given 1 hour before induction of anesthesia. The manufacturer states that oral or IV dosage modification is not necessary in geriatric patients and that there is no experience with the use of oral ondansetron for the prevention of postoperative nausea and vomiting in children.

As an alternative to IV administration for the prevention of postoperative nausea and vomiting in adults, an ondansetron dose of 4 mg may be given IM undiluted as a single injection.

Radiation-induced Nausea and Vomiting

For prevention of radiation-induced nausea and vomiting in adults undergoing total body irradiation or single high-dose fraction or daily fractionated radiation to the abdomen, the usual oral dosage of ondansetron is 8 mg 3 times daily. Patients undergoing total body irradiation should receive one 8-mg dose 1-2 hours before each fraction of radiation therapy each day. Patients undergoing single high-dose fraction radiation therapy to the abdomen should receive one 8-mg dose 1-2 hours before radiation, with subsequent doses administered every 8 hours for 1-2 days after completion of radiation therapy. For patients undergoing daily fractionated radiation to the abdomen, one 8-mg dose should be given 1-2 hours before radiation therapy and then every 8 hours, with this regimen repeated for each day radiation therapy is given. The manufacturer states that dosage modification is not necessary in geriatric patients and that there is no experience with use of the drug for the prevention of radiation-induced nausea and vomiting in children.

Dosage in Renal and Hepatic Impairment

The manufacturer states that patients with renal impairment do not require ondansetron dosage adjustment, but there is no experience with continuing ondansetron beyond the first day of therapy in such patients. Although only about 5% of the drug is eliminated by the kidneys and renal impairment was not expected to substantially alter elimination of ondansetron, mean plasma clearance has been decreased by about 41-50% in patients with severe renal impairment (creatinine clearances less than 30 mL/minute). However, the decrease in clearance was variable and not consistent with an increase in plasma half-life of the drug. In patients with severe hepatic impairment (Child-Pugh score of 10 or greater) clearance is decreased and apparent volume of distribution of ondansetron is increased with a resultant increase in plasma half-life; therefore, the manufacturer recommends that the total daily dose not exceed 8 mg in such patients.

Cautions

Ondansetron generally is well tolerated. Most adverse effects reported in clinical trials have been mild to moderate in severity. Adverse effects rarely have resulted in discontinuance of the drug. The most frequent adverse effects of ondansetron in patients receiving the drug for the prevention of chemotherapy-induced nausea and vomiting involve the nervous system (e.g., headache) and GI tract (e.g., diarrhea, constipation). Because most patients receiving ondansetron in clinical trials for chemotherapy-induced nausea and vomiting had serious underlying disease (e.g., cancer) and were receiving toxic drugs (e.g., cisplatin), diuretics, and IV fluids concomitantly, it may be difficult to attribute various adverse effects to ondansetron. In trials comparing ondansetron and metoclopramide, adverse effects occurring substantially more frequently for one drug compared with the other included headache and constipation for ondansetron and diarrhea and extrapyramidal/dystonic manifestations for metoclopramide; adverse effects resulting in drug discontinuance were less common with ondansetron.

The adverse effect profile of ondansetron in patients receiving the drug for the prevention of radiation-induced nausea and vomiting is similar to that in patients receiving the drug for the prevention of chemotherapy-induced nausea and vomiting, although specific incidences of effects may vary; the most common adverse effects of the drug in patients undergoing radiation were headache, constipation, and diarrhea.

In clinical trials in patients receiving ondansetron for the prevention of postoperative nausea and vomiting, the incidences of adverse effects associated with ondansetron, with the exception of headache, did not differ substantially from those associated with placebo. Most such patients were receiving concomitantly multiple preoperative and postoperative drugs. Studies of oral ondansetron for the prevention of postoperative nausea and vomiting to date have included only women undergoing inpatient surgical procedures; no studies have been performed in males.

Nervous System Effects

Headache is the most common adverse nervous system effect of ondansetron, occurring in 11-24% of patients receiving the drug orally or IV in recommended dosages for prevention of chemotherapy-induced nausea and vomiting and in 9-17% of those receiving the drug for postoperative nausea and vomiting in controlled clinical trials; headache occurred in 5% of patients receiving ondansetron for radiation-induced nausea and vomiting. Preliminary observations in a small number of patients suggest that headache occurs more frequently when ondansetron orally disintegrating tablets are taken with water as compared to ingestion without water. Headache generally is mild to moderate in severity and generally responds to mild analgesics. While some evidence suggests that the incidence of headache may be dose related, other evidence failed to establish a clear relationship, particularly regarding severity. Migraine headache has been reported rarely with oral or IV ondansetron.

Dizziness has been reported in 7% of patients receiving ondansetron orally in recommended dosages for prevention of postoperative nausea and vomiting in controlled clinical trials. Dizziness has occurred occasionally in patients receiving the drug IV (mainly during or shortly after IV infusion) and in 4-5% of patients receiving ondansetron orally for prevention of chemotherapy-induced nausea and vomiting; however, a direct causal relationship to the drug has not been established. Although not directly attributed to the drug, other adverse nervous system effects reported include drowsiness or sedation, which occurred in 8%, and paresthesia, which occurred in 2%, of patients receiving the drug IV in the recommended dosage for prevention of postoperative nausea and vomiting; these effects also occurred occasionally in patients receiving the drug orally or IV for prevention of chemotherapy-induced nausea and vomiting. Drowsiness/sedation occurred in 20%, and anxiety/agitation in 6%, of patients receiving oral ondansetron for prevention of postoperative nausea and vomiting in clinical trials. Anxiety or agitation also has occurred in patients receiving the drug IV for prevention of postoperative nausea and vomiting.

Although extrapyramidal reactions were not reported with ondansetron in clinical trials comparing the drug with metoclopramide, manifestations consistent with, but not necessarily diagnostic of, such reactions have been reported rarely in patients receiving ondansetron. Oculogyric crisis, appearing alone, as well as other dystonic reactions, have been reported during postmarketing experience in patients receiving IV ondansetron.

Restlessness, akathisia, ataxia, lightheadedness, and insomnia have been reported rarely with IV ondansetron. Lightheadedness was reported mainly during IV infusion of ondansetron and resolved rapidly. Panic attacks also have been reported rarely.

Seizures (including tonic-clonic seizures) have been reported rarely in patients receiving ondansetron.

GI Effects

Diarrhea is the most common adverse GI effect of ondansetron, occurring in 16% of patients receiving the drug IV in recommended dosages for prevention of chemotherapy-induced nausea and vomiting in controlled clinical trials and in 4-6% of patients receiving the drug orally in recommended dosages. Because most patients receiving ondansetron IV for chemotherapy-induced nausea and vomiting were receiving cisplatin concomitantly, which can cause diarrhea, a causal relationship to ondansetron has not been established. Constipation occurred in 3% of ondansetron-treated patients receiving single-day IV therapy, but is more common in patients receiving multiple-day therapy, occurring in 11% of patients receiving multiple-day IV therapy and in 6-9% of patients receiving multiple-day oral therapy in the recommended dosage for chemotherapy-induced nausea and vomiting. The incidence of constipation may be dose related. Dyspepsia or heartburn, thirst, flatulence, abdominal cramps, abdominal pain, abnormal taste, anorexia, xerostomia, and intestinal obstruction also have been reported with oral or IV ondansetron for prevention of chemotherapy-induced nausea and vomiting.

Hepatic Effects

Increased serum concentrations of ALT (SGPT) and AST (SGOT) exceeding twice the upper limit of normal have been reported in approximately 1-2% of patients receiving ondansetron orally for prevention of chemotherapy-induced nausea and vomiting, in approximately 5% of patients receiving the drug IV for prevention of chemotherapy-induced nausea and vomiting, and in approximately 1% of patients receiving the drug IV for prevention of postoperative nausea and vomiting. The increases were transient and appeared to be unrelated to dose or duration of ondansetron therapy; however, similar transient increases recurred in some courses of therapy with repeat exposure to the drug, but symptomatic hepatic disease did not occur. In patients with cancer, the role of cancer chemotherapy in these increases cannot be clearly determined. Hepatosplenomegaly, jaundice, and increased serum concentrations of bilirubin and γ-glutamyltransferase (GGT, γ-glutamyltranspeptidase, GGTP) also have been reported rarely.

Liver failure and death have been reported rarely in patients with cancer receiving ondansetron concomitantly with other drugs, including potentially hepatotoxic cytotoxic chemotherapy and antibiotics; the etiology of the liver failure is unclear.

Dermatologic and Sensitivity Reactions

Pruritus has been reported in 2% of patients receiving ondansetron IV and in 5% of those receiving the drug orally for prevention of postoperative nausea and vomiting in controlled clinical trials. Rash, which may be maculopapular and/or accompanied by pruritus, has occurred in approximately 1% of patients receiving the drug orally or IV for prevention of chemotherapy-induced nausea and vomiting in controlled clinical trials. Rarely, rash may be followed by desquamation and hyperpigmentation.

Serious hypersensitivity reactions have occurred in patients receiving ondansetron orally or IV. In patients with cancer, these reactions have been reported to occur mainly following the first dose during the second or third course of cancer chemotherapy. These reactions may include anaphylaxis/anaphylactoid reactions, angioedema, bronchospasm, cardiopulmonary arrest, hypotension, laryngeal edema, laryngospasm, shock, shortness of breath, stridor, wheezing, facial edema, and urticaria. Sensitivity reactions also have been reported in patients who have exhibited sensitivity to other selective 5-HT3-receptor antagonists. If a hypersensitivity reaction occurs during ondansetron therapy, the drug should be discontinued, and severe acute hypersensitivity reactions should be treated with appropriate therapy (e.g., epinephrine, corticosteroids, maintenance of an adequate airway, oxygen, IV fluids, antihistamines, maintenance of blood pressure) as indicated.

Cardiovascular Effects

Prolongation of the QT interval and cases of torsades de pointes have been reported in patients receiving ondansetron. Preliminary results of a randomized, double-blind, placebo- and active-controlled crossover study conducted in healthy adults to assess the drug's effects on the QT interval indicate that ondansetron prolongs the QT interval in a dose-dependent manner. Following IV infusion of ondansetron 8 or 32 mg over 15 minutes, the maximum mean baseline-corrected increase in the QTc interval (QT interval corrected for heart rate using Fridericia's formula) relative to placebo was 5.8 or 19.6 milliseconds, respectively. Other studies in postoperative patients or healthy individuals also suggest that ondansetron can prolong the QT interval. Based on these findings, an antiemetic regimen consisting of a single IV ondansetron dose of 32 mg given prior to emetogenic cancer chemotherapy no longer is recommended. Individual IV doses of the drug should not exceed 16 mg.(See Cautions: Precautions and Contraindications.)

Hypotension has occurred in 5% of patients receiving oral ondansetron for prevention of postoperative nausea and vomiting. Unspecified chest pain and hypotension have been reported in patients receiving ondansetron IV for prevention of postoperative nausea and vomiting in controlled clinical trials, but these effects have not been directly attributed to the drug.

Angina (chest pain), hypotension, flushing, tachycardia, ECG alterations (including arrhythmias and prolongation of PR, QRS, and QT intervals), and vascular occlusive events (e.g., myocardial infarction, cerebrovascular accident, pulmonary embolism, deep-vein thrombosis) have been reported rarely during clinical trials or postmarketing experience in patients receiving ondansetron orally or IV for prevention of chemotherapy-induced nausea and vomiting; a definite causal relationship to the drug has not been established. Arrhythmias (including ventricular and supraventricular tachycardia, premature ventricular complexes, and atrial fibrillation), bradycardia, ECG alterations (including second-degree heart block and ST-segment depression), hypertension, syncope, and palpitations have been reported in patients receiving IV ondansetron, although these effects have not been directly attributed to the drug. Transient ECG alterations including QT-interval prolongation have been reported rarely, mainly in patients receiving the drug IV; cases of torsades de pointes have been reported during postmarketing experience in patients receiving ondansetron. Bradycardia also was reported in 6% of patients receiving oral ondansetron in clinical trials for prevention of postoperative nausea and vomiting.

Ocular Effects

Transient blurred vision, occasionally associated with abnormalities of accommodation, has been reported rarely in patients during or shortly after IV infusion of ondansetron. This adverse effect may be ameliorated with a slower infusion rate or following discontinuance of the infusion. Transient blindness, which resolved within a few minutes to 48 hours, also has been reported, generally during IV administration of the drug.

Other Adverse Effects

Fever occurred in 8% of patients receiving ondansetron IV for prevention of chemotherapy-induced nausea and vomiting and in 2% of patients receiving the drug IV for prevention of postoperative nausea and vomiting in controlled clinical trials. Malaise or fatigue was reported in 9-13% and weakness was reported in up to 2% of patients receiving ondansetron orally for prevention of chemotherapy-induced nausea and vomiting. Pyrexia was reported in 8% of patients receiving oral ondansetron for prevention of postoperative nausea and vomiting in controlled trials. Shivers have been reported in 5% of patients receiving ondansetron orally for prevention of postoperative nausea and vomiting in controlled clinical trials, and occasionally in patients receiving the drug orally for prevention of chemotherapy-induced nausea and vomiting. However, these effects have not been directly attributed to the drug. Sweating also has been reported rarely with IV ondansetron.

Injection site reactions (including pain, erythema, swelling, and burning) occurred in 4% of patients receiving ondansetron IV for prevention of postoperative nausea and vomiting and occasionally in patients receiving the drug IV for prevention of chemotherapy-induced nausea and vomiting in controlled clinical trials. Wound problems were reported in 28% of patients receiving ondansetron orally for postoperative nausea and vomiting in controlled trials. Throat problems and hemorrhage also have been reported in patients receiving ondansetron orally or IV for prevention of postoperative nausea and vomiting.

Cold sensation occurred in 2% of patients receiving ondansetron IV for prevention of postoperative nausea and vomiting in controlled clinical trials, although a causal relationship has not been established. Urinary retention has occurred in 5%, and gynecologic disorder in 7%, of patients receiving oral ondansetron for prevention of postoperative nausea and vomiting. Sensation of cold has been reported in patients receiving ondansetron IV for prevention of chemotherapy-induced nausea and vomiting; sensation of warmth also has been reported rarely with IV ondansetron therapy. Musculoskeletal pain has been reported in patients receiving IV ondansetron. Hypoxia has been reported in 9% of those receiving the drug orally for postoperative nausea and vomiting. Dyspnea, hypoxia, and hiccups also have been reported with ondansetron.

Although a definite causal relationship to ondansetron has not been established, hypokalemia has been reported rarely in patients receiving the drug orally or IV for prevention of cancer chemotherapy-induced nausea and vomiting.

Precautions and Contraindications

Because of the risk of QT-interval prolongation, ondansetron should be avoided in patients with congenital long QT syndrome. ECG monitoring is recommended in patients with electrolyte abnormalities such as hypokalemia or hypomagnesemia, congestive heart failure, or bradyarrhythmias and in those receiving other drugs known to prolong the QT interval. Electrolyte abnormalities should be corrected prior to IV administration of ondansetron. Because effects of ondansetron on the QT interval are dose related, use of single IV doses exceeding 16 mg should be avoided. Patients receiving ondansetron should be advised to seek immediate medical care if feelings of faintness, lightheadedness, irregular heartbeat, shortness of breath, or dizziness occur.

Like other antiemetics, ondansetron may mask a progressive ileus and/or gastric distention in patients undergoing abdominal surgery or in patients with chemotherapy-induced nausea and vomiting.

Because ondansetron does not stimulate gastric or intestinal peristalsis, it should not be used as a substitute for nasogastric suction.

Because clearance of ondansetron is decreased and apparent volume of distribution and plasma half-life are increased in patients with severe hepatic impairment, the drug should be used with caution and at reduced dosage in such patients.(See Dosage and Administration: Dosage in Renal and Hepatic Impairment.)

Ondansetron rarely may cause serious hypersensitivity reactions, and patients should be advised of this possibility and instructed to discontinue the drug and contact their clinician at the first sign of rash or any other sign of hypersensitivity.(See Cautions: Dermatologic and Sensitivity Reactions.) Ondansetron is contraindicated in patients with known hypersensitivity to the drug or any ingredient in the formulation.

Because profound hypotension and loss of consciousness have been reported when ondansetron was administered concomitantly with apomorphine, concomitant use of these drugs is contraindicated.

Individuals with phenylketonuria (i.e., homozygous genetic deficiency of phenylalanine hydroxylase) and other individuals who must restrict their intake of phenylalanine should be warned that each 4- and 8-mg Zofran ODT orally disintegrating tablet contains aspartame (NutraSweet), which is metabolized in the GI tract to provide less than 0.03 mg of phenylalanine following oral administration.

Pediatric Precautions

The manufacturer states that little information is available on IV use of ondansetron for the prevention of postoperative nausea and vomiting in pediatric patients younger than 1 month of age or for the prevention of cancer chemotherapy-induced nausea and vomiting in pediatric patients younger than 6 months of age. Little information is available on oral dosage of ondansetron in pediatric patients 4 years of age or younger. Efficacy of the single 24-mg oral dose of ondansetron for the prevention of nausea and vomiting induced by highly emetogenic cancer chemotherapy in pediatric patients younger than 18 years of age has not been established. Efficacy of oral ondansetron for prevention of radiation-induced and postoperative nausea and vomiting in pediatric patients younger than 18 years of age has not been established. In prevention of cancer chemotherapy-induced emesis, safety and efficacy of the drug orally and IV generally are comparable to that observed in older children and adults.

In placebo-controlled trials evaluating IV ondansetron for prevention of postoperative nausea and vomiting in pediatric patients, adverse effects occurred at similar frequencies in pediatric patients receiving recommended dosages of ondansetron and those receiving placebo; however, among pediatric patients 1-24 months of age, diarrhea occurred more frequently in those receiving ondansetron compared with those receiving placebo (2 versus less than 1%).

Pediatric cancer or surgical patients younger than 18 years of age generally tend to have higher clearances and shorter half-lives of ondansetron compared with adults. However, in infants 1-4 months of age, clearance of the drug is reduced and half-life is prolonged (by approximately 2.5-fold relative to values in infants older than 4 months up to 24 months of age); thus, the manufacturer recommends that infants younger than 4 months of age receiving ondansetron therapy be closely monitored.

Geriatric Precautions

While safety and efficacy of ondansetron have not been established specifically in geriatric patients, a large proportion of patients treated with the drug for chemotherapy-induced nausea and vomiting and prevention of postoperative nausea and/or vomiting have been 65 years of age or older. Plasma clearance of ondansetron may be decreased and elimination half-life increased in patients older than 75 years of age. In clinical studies with ondansetron that included patients 65 years of age and older, no overall differences in efficacy or safety were observed between patients in this age group and younger patients. However, the possibility that some older patients may exhibit increased sensitivity to the drug cannot be ruled out.

Mutagenicity and Carcinogenicity

Ondansetron was not mutagenic in standard tests performed for mutagenicity. In rats and mice receiving oral dosages up to 10 and 30 mg/kg daily, respectively (approximately 3.6 and 5.4 times, respectively, the recommended human IV dosage of 0.15 mg/kg given 3 times daily [calculated on the basis of body surface area]), ondansetron did not produce evidence of carcinogenicity.

Pregnancy, Fertility, and Lactation

Pregnancy

Reproduction studies in rats and rabbits receiving oral ondansetron dosages up to 15 and 30 mg/kg daily, respectively, and IV ondansetron dosages up to 4 mg/kg daily (approximately 1.4 and 2.9 times, respectively, the recommended human IV dosage of 0.15 mg/kg given 3 times daily [calculated on the basis of body surface area]) have not revealed evidence of harm to the fetus. There are no adequate and controlled studies to date using ondansetron in pregnant women, and the drug should be used during pregnancy only when clearly needed.

Fertility

Reproduction studies in male and female rats using oral ondansetron dosages up to 15 mg/kg daily (approximately 3.8 times the recommended human IV dosage based on body surface area) have not revealed evidence of impaired fertility.

Lactation

It is not known whether ondansetron is distributed into human milk; however, the drug is distributed into the milk of lactating rats. Because many drugs are distributed in human milk, ondansetron should be used with caution in nursing women.

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