EMESET Tablets (Ondansetron hydrochloride)

Table of Content

Composition

EMESET 4 Tablets
Each film coated tablet contains
Ondansetron hydrochloride
Equivalent to Ondansetron ….....................4 mg

EMESET 8 Tablets
Each film coated tablet contains
Ondansetron hydrochloride
Equivalent to Ondansetron ……………… 8 mg

EMESET SYRUP
Each 5 ml contains
Ondansetron hydrochloride USP
Equivalent to Ondansetron..... 2 mg
In a flavoured base....................q.s.

Colours: Sunset Yellow FCF & Carmoisine

Dosage Form/S

Tablets and syrup for oral use

Pharmacology

Pharmacodynamics

Ondansetron is a selective 5-HT3 receptor antagonist. While its mechanism of action has not been fully characterized, ondansetron is not a dopamine-receptor antagonist. Serotonin receptors of the 5-HT3 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-HIAA (5-hydroxyindoleacetic acid) excretion increases after cisplatin administration in parallel with the onset of emesis. The released serotonin may stimulate the vagal afferents through the 5-HT3 receptors and initiate the vomiting reflex.

In animals, the emetic response to cisplatin can be prevented by pretreatment with an inhibitor of serotonin synthesis, bilateral abdominal vagotomy and greater splanchnic nerve section, or pretreatment with a serotonin 5-HT3 receptor antagonist.

In normal volunteers, single intravenous doses of 0.15 mg/kg of ondansetron had no effect on esophageal motility, gastric motility, lower esophageal sphincter pressure, or small intestinal transit time. Multiday administration of ondansetron has been shown to slow colonic transit in normal volunteers. Ondansetron has no effect on plasma prolactin concentrations.

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.

Pharmacokinetics

Ondansetron is well absorbed from the gastrointestinal tract and undergoes some first-pass metabolism. Mean bioavailability in healthy subjects, following administration of a single 8-mg tablet, is approximately 56%.

Ondansetron systemic exposure does not increase proportionately to dose. AUC from a 16-mg tablet was 24% greater than predicted from an 8-mg tablet dose. This may reflect some reduction of first-pass metabolism at higher oral doses. Bioavailability is also slightly enhanced by the presence of food but unaffected by antacids.

Ondansetron is extensively metabolized in humans, with approximately 5% of a radiolabeled dose recovered as the parent compound from the urine. The primary metabolic pathway is hydroxylation on the indole ring followed by subsequent glucuronide or sulfate conjugation. Although some nonconjugated metabolites have pharmacologic activity, these are not found in plasma at concentrations likely to significantly contribute to the biological activity of ondansetron.

In vitro metabolism studies have shown that ondansetron is a substrate for human hepatic cytochrome P-450 enzymes, including CYP1A2, CYP2D6, and CYP3A4. In terms of overall ondansetron turnover, CYP3A4 played the predominant role. Because of the multiplicity of metabolic enzymes capable of metabolizing ondansetron, it is likely that inhibition or loss of one enzyme (e.g., CYP2D6 genetic deficiency) will be compensated by others and may result in little change in overall rates of ondansetron elimination. Ondansetron elimination may be affected by cytochrome P-450 inducers. In a pharmacokinetic study of 16 epileptic patients maintained chronically on CYP3A4 inducers, carbamazepine, or phenytoin, reduction in AUC, Cmax, and t½ of ondansetron was observed. This resulted in a significant increase in clearance. However, on the basis of available data, no dosage adjustment for ondansetron is recommended.

In humans, carmustine, etoposide, and cisplatin do not affect the pharmacokinetics of ondansetron.

Gender differences were shown in the disposition of ondansetron given as a single dose. The extent and rate of ondansetron's absorption is greater in women than men. Slower clearance in women, a smaller apparent volume of distribution (adjusted for weight), and higher absolute bioavailability resulted in higher plasma ondansetron levels. These higher plasma levels may in part be explained by differences in body weight between men and women. It is not known whether these gender-related differences were clinically important. More detailed pharmacokinetic information is contained in Table 1 taken from a study.

Table 1. Pharmacokinetics in normal volunteers: single 8-mg ondansetron tablet dose
Age-group
(years)
Mean
Weight
(kg)
n
Peak Plasma
Concentration
(ng/mL)
Time of
Peak Plasma
Concentration
(h)
Mean
Elimination
Half-life
(h)
Systemic
Plasma
Clearance
L/h/kg
Absolute
Bioavailability
18-40
M
F

69.0
62.7

6
5

26.2
42.7

2.0
1.7

3.1
3.5

0.403
0.354

0.483
0.663
61-74
M
F

77.5
60.2

6
6

24.1
52.4

2.1
1.9

4.1
4.9

0.384
0.255

0.585
0.643
≥ 75
M
F

78.0
67.6

5
6

37.0
46.1

2.2
2.1

4.5
6.2

0.277
0.249

0.619
0.747

A reduction in clearance and increase in elimination half-life are seen in patients over 75 years of age. In clinical trials with cancer patients, safety and efficacy were similar in patients over 65 years of age and those under 65 years of age; there was an insufficient number of patients over 75 years of age to permit conclusions in that age-group. No dosage adjustment is recommended in the elderly.

Hepatic impairment
In patients with mild-to-moderate hepatic impairment, clearance is reduced 2-fold and mean half-life is increased to 11.6 hours compared to 5.7 hours in normal. In patients with severe hepatic impairment (Child-Pugh2 score of 10 or greater), clearance is reduced 2-fold to 3-fold and apparent volume of distribution is increased with a resultant increase in half-life to 20 hours. In patients with severe hepatic impairment, a total daily dose of 8 mg should not be exceeded.

Renal impairment
Due to the very small contribution (5%) of renal clearance to the overall clearance, renal impairment was not expected to significantly influence the total clearance of ondansetron. However, ondansetron oral mean plasma clearance was reduced by about 50% in patients with severe renal impairment (creatinine clearance < 30 mL/min). This reduction in clearance is variable and was not consistent with an increase in half-life. No reduction in dose or dosing frequency in these patients is warranted.

Plasma protein binding of ondansetron as measured in vitro was 70% to 76% over the concentration range of 10 to 500 ng/mL. Circulating drug also distributes into erythrocytes.

Four- and 8-mg doses of either ondansetronsyrupis bioequivalent to corresponding doses of ondansetron Tablets and may be used interchangeably.

Indications

  • Prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin ≥ 50 mg/m2
  • Prevention of nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy.
  • Prevention of nausea and vomiting associated with radiotherapy in patients receiving total body irradiation, single high-dose fraction to the abdomen, or daily fractions to the abdomen.
  • 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 where nausea and/or vomiting must be avoided postoperatively, ondansetron tablets, and syrup are recommended even where the incidence of postoperative nausea and/or vomiting is low.

Dosage and Administration

Prevention of Nausea and Vomiting Associated With Highly Emetogenic Cancer Chemotherapy

The recommended adult oral dosage of ondansetron is 24 mg given as three 8-mg tablets administered 30 minutes before the start of single-day highly emetogenic chemotherapy, including cisplatin ≥ 50 mg/m2. Multiday, single-dose administration of a 24 mg dosage has not been studied.

Pediatric Use
There is no experience with the use of a 24 mg dosage in pediatric patients.

Geriatric Use
The dosage recommendation is the same as for the general population.

Prevention of Nausea and Vomiting Associated With Moderately Emetogenic Cancer Chemotherapy

The recommended adult oral dosage is one 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup given twice a day. The first dose should be administered 30 minutes before the start of emetogenic chemotherapy, with a subsequent dose 8 hours after the first dose. One 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup should be administered twice a day (every 12 hours) for 1 to 2 days after completion of chemotherapy.

Pediatric Use
For pediatric patients 12 years of age and older, the dosage is the same as for adults. For pediatric patients 4 through 11 years of age, the dosage is one 4-mg ondansetron tablet or 5 ml (1 teaspoonful equivalent to 4 mg of ondansetron) of ondansetron syrup given 3 times a day. The first dose should be administered 30 minutes before the start of emetogenic chemotherapy, with subsequent doses 4 and 8 hours after the first dose. One 4-mg ondansetron tablet or 5 ml (1 teaspoonful equivalent to 4 mg of ondansetron) of ondansetron syrup should be administered 3 times a day (every 8 hours) for 1 to 2 days after completion of chemotherapy.

Geriatric use
The dosage is the same as for the general population.

Prevention of Nausea and Vomiting Associated With Radiotherapy, Either Total Body Irradiation, or Single High-Dose Fraction or Daily Fractions to the Abdomen

The recommended oral dosage is one 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup given 3 times a day.

For total body irradiation, one 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup should be administered 1 to 2 hours before each fraction of radiotherapy administered each day.

For single high-dose fraction radiotherapy to the abdomen, one 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup should be administered 1 to 2 hours before radiotherapy, with subsequent doses every 8 hours after the first dose for 1 to 2 days after completion of radiotherapy.

For daily fractionated radiotherapy to the abdomen, one 8-mg ondansetron tablet or 10 ml (2 teaspoonfuls equivalent to 8 mg of ondansetron) of ondansetron syrup should be administered 1 to 2 hours before radiotherapy, with subsequent doses every 8 hours after the first dose for each day radiotherapy is given.

Pediatric Use
There is no experience with the use of ondansetron tablets, or ondansetron syrup in the prevention of postoperative nausea and vomiting in pediatric patients.

Geriatric Use
The dosage is the same as for the general population.

Postoperative Nausea and Vomiting

The recommended dosage is 16 mg given as two 8-mg ondansetron tablets or 20 ml (4 teaspoonfuls equivalent to 16 mg of ondansetron) of ondansetron syrup 1 hour before induction of anesthesia.

Pediatric Use
There is no experience with the use of ondansetron tablets, or ondansetron syrup in the prevention of postoperative nausea and vomiting in pediatric patients.

Geriatric Use
The dosage is the same as for the general population.

Impaired Renal Function
The dosage recommendation is the same as for the general population. There is no experience beyond first-day administration of ondansetron.

Impaired Hepatic Function
In patients with severe hepatic impairment (Child-Pugh2 score of 10 or greater), clearance is reduced and apparent volume of distribution is increased with a resultant increase in plasma half-life. In such patients, a total daily dose of 8 mg should not be exceeded.

Contraindications

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.
Ondansetron tablets, and ondansetron syrup are contraindicated for patients known to have hypersensitivity to the drug.

Warnings and Precautions

Hypersensitivity reactions have been reported in patients who have exhibited hypersensitivity to other selective 5-HT3 receptor antagonists.

ECG changes including QT interval prolongation has been seen in patients receiving ondansetron. In addition, post-marketing cases of torsade de pointes have been reported in patients using ondansetron. Avoid ondansetron 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.

General

Ondansetron is not a drug that stimulates gastric or intestinal peristalsis. It should not be used instead of nasogastric suction. The use of ondansetron in patients following abdominal surgery or in patients with chemotherapy-induced nausea and vomiting may mask a progressive ileus and/or gastric distension.

Drug interactions

Ondansetron does not itself 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. On the basis of available data, no dosage adjustment is recommended for patients on these drugs.

Apomorphine
Based on reports of profound hypotension and loss of consciousness when apomorphine was administered with ondansetron, concomitant use of apomorphine with ondansetron is contraindicated.

Phenytoin, Carbamazepine, and Rifampicin
In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampicin), 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.

Tramadol
Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small studies indicate that ondansetron may be associated with an increase in patient controlled administration of tramadol.

Chemotherapy
Tumor response to chemotherapy in the P-388 mouse leukemia model is not affected by ondansetron. In humans, carmustine, etoposide, and cisplatin do not affect the pharmacokinetics of ondansetron.

In a crossover study in 76 pediatric patients, I.V. ondansetron did not increase blood levels of high-dose methotrexate.

Use in Surgical Patients

The coadministration of ondansetron had no effect on the pharmacokinetics and pharmacodynamics of temazepam.

Renal impairment

The dosage recommendation is the same as for the general population. There is no experience beyond first-day administration of ondansetron.

Hepatic impairment

In patients with severe hepatic impairment (Child-Pugh2 score of 10 or greater), clearance is reduced and apparent volume of distribution is increased with a resultant increase in plasma half-life. In such patients, a total daily dose of 8 mg should not be exceeded.

Pregnancy

Teratogenic Effects
Pregnancy Category B. Reproduction studies have been performed in pregnant rats and rabbits at daily oral doses up to 15 and 30 mg/kg/day, respectively, and have revealed no evidence of impaired fertility or harm to the fetus due to ondansetron. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Lactation

Ondansetron is excreted in the breast milk of rats. It is not known whether ondansetron is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ondansetron is administered to a nursing woman.

Pediatric Use

Little information is available about dosage in pediatric patients 4 years of age or younger.

Geriatric Use

Of the total number of subjects enrolled in cancer chemotherapy-induced and postoperative nausea and vomiting in US- and foreign-controlled clinical trials, for which there were subgroup analyses, 938 were 65 years of age and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Dosage adjustment is not needed in patients over the age of 65.

Undesirable Effects

The following have been reported as adverse events in clinical trials of patients treated with ondansetron, the active ingredient of ondansetron. A causal relationship to therapy with ondansetron has been unclear in many cases.

Chemotherapy-induced Nausea and Vomiting

The adverse events in table 2 have been reported in ≥ 5% of adult patients receiving a single 24-mg ondansetron tablet in 2 trials. These patients were receiving concurrent highly emetogenic cisplatin-based chemotherapy regimens (cisplatin dose ≥ 50 mg/m2).

Table 2. Principal adverse events in US trials: single day therapy with 24-mg ondansetron tablets (Highly Emetogenic Chemotherapy)
Adverse Event
Ondansetron
24 mg q.d.
n = 300
Ondansetron
8 mg b.i.d.
n = 124
Ondansetron
32 mg q.d.
n = 117
Headache
33 (11%)
16 (13%)
17 (15%)
Diarrhea
13 (4%)
9 (7%)
3 (3%)

The adverse events in Table 3 have been reported in ≥ 5% of adults receiving either 8 mg of ondansetron tablets 2 or 3 times a day for 3 days or placebo in 4 trials. These patients were receiving concurrent moderately emetogenic chemotherapy, primarily cyclophosphamide-based regimens.

Table 3. Principal adverse events in us trials: 3 days of therapy with 8-mg ondansetron tablets (moderately emetogenic chemotherapy)
Adverse Event
Ondansetron 8
mg b.i.d.
n = 242
Ondansetron 8
mg t.i.d.
n = 415
Placebo
n = 262
Headache
58 (24%)
113 (27%)
34 (13%)
Malaise/fatigue
32 (13%)
37 (9%)
6 (2%)
Constipation
22 (9%)
26 (6%)
1 (
Diarrhea
15 (6%)
16 (4%)
10 (4%)
Dizziness
13 (5%)
18 (4%)
12 (5%)

Central Nervous System
There have been rare reports consistent with, but not diagnostic of, extrapyramidal reactions in patients receiving ondansetron.

Hepatic
In 723 patients receiving cyclophosphamide-based chemotherapy in US clinical trials, AST and/or ALT values have been reported to exceed twice the upper limit of normal in approximately 1% to 2% of patients receiving ondansetron tablets. 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. The role of cancer chemotherapy in these biochemical changes cannot be clearly determined.
There have been reports of liver failure and death in patients with cancer receiving concurrent medications including potentially hepatotoxic cytotoxic chemotherapy and antibiotics. The etiology of the liver failure is unclear.

Integumentary
Rash has occurred in approximately 1% of patients receiving ondansetron.

Other
Rare cases of anaphylaxis, bronchospasm, tachycardia, angina (chest pain), hypokalemia, electrocardiographic alterations, vascular occlusive events, and grand mal seizures have been reported. Except for bronchospasm and anaphylaxis, the relationship to ondansetron was unclear.

Radiation-Induced Nausea and Vomiting

The adverse events reported in patients receiving ondansetron tablets and concurrent radiotherapy were similar to those reported in patients receiving ondansetron tablets and concurrent chemotherapy. The most frequently reported adverse events were headache, constipation, and diarrhea.

Postoperative Nausea and Vomiting

The adverse events in Table 4 have been reported in ≥ 5% of patients receiving ondansetron tablets at a dosage of 16 mg orally in clinical trials. With the exception of headache, rates of these events were not significantly different in the ondansetron and placebo groups. These patients were receiving multiple concomitant perioperative and postoperative medications.

Table 4. Frequency of adverse events from controlled studies with ondansetron tablets (Postoperative Nausea and Vomiting)
Advese Event
Ondansetron 16 mg
(n = 550)
Placebo
(n = 531)
Wound problem
152 (28%)
162 (31%)
Drowsiness/sedation
112 (20%)
122 (23%)
Headache
49 (9%)
27 (5%)
Hypoxia
49 (9%)
35 (7%)
Pyrexia
45 (8%)
34 (6%)
Dizziness
36 (7%)
34 (6%)
Gynecological disorder
36 (7%)
33 (6%)
Anxiety/agitation
33 (6%)
29 (5%)
Bradycardia
32 (6%)
30 (6%)
Shiver(s)
28 (5%)
30 (6%)
Urinary retention
28 (5%)
18 (3%)
Hypotension
27 (5%)
32 (6%)
Pruritus
27 (5%)
20 (4%)

Preliminary observations in a small number of subjects suggest a higher incidence of headache when ondansetron ODT are taken with water, when compared to without water

Observed During Clinical Practice

In addition to adverse events reported from clinical trials, the following events have been identified during post-approval use of oral formulations of ondansetron. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. The events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to ondansetron.

Cardiovascular
Rarely and predominantly with intravenous ondansetron, transient ECG changes including QT interval prolongation have been reported.

General
Flushing,rare cases of hypersensitivity reactions, sometimes severe (e.g., anaphylaxis/anaphylactoid reactions, angioedema, bronchospasm, shortness of breath, hypotension, laryngeal edema, stridor) have also been reported. Laryngospasm, shock, and cardiopulmonary arrest have occurred during allergic reactions in patients receiving injectable ondansetron.

Hepatobiliary
Liver enzyme abnormalities

Lower Respiratory
Hiccups

Neurology
Oculogyric crisis, appearing alone, as well as with other dystonic reactions

Skin
Urticaria

Special Senses
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.

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 events 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 1 patient that was administered 72 mg of ondansetron intravenously as a single dose. Hypotension (and faintness) occurred in a patient that took 48 mg of ondansetron tablets. 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.

Storage and Handling Instructions

Store in a cool and dry place. Protect from light.

Packaging Information

EMESET 4:Strip of 10 tablets
EMESET 8:Strip of 10 tablets
EMESET-2 ODT: Blister pack of 10 tablets
EMESET:Bottle of 30 mlsyrup