Ondansetron

What is Ondansetron?

• Ondansetron (Zofran; Zofran ODT; Zuplenz) is a 5-HT3 receptor antagonist used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery.

Ondansetron skeletal

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What are the uses of this medicine?

Ondansetron (Zofran; Zofran ODT; Zuplenz) is used 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.

• Ondansetron tablets are also indicated for the prevention of postoperative nausea and/or vomiting.

How does this medicine work?

• The hydrochloride salt of the racemic form of ondansetron, a carbazole derivative and a selective, competitive serotonin 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist with antiemetic activity.
• Although its mechanism of action has not been fully characterized, ondansetron appears to competitively block the action of serotonin at 5HT3 receptors peripherally in the gastrointestinal tract as well as centrally in the area postrema of the CNS, where the chemoreceptor trigger zone (CTZ) for vomiting is located, resulting in the suppression of chemotherapy- and radiotherapy-induced nausea and vomiting.

Who Should Not Use this medicine ?

This medicine cannot be used in patients with:

• known to have hypersensitivity (e.g., anaphylaxis) to ondansetron or any of the components of the formulation.
• receiving concomitant apomorphine.

What drug interactions can this medicine cause?

• Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Be sure to mention any of the following:

• certain medications for seizures such as carbamazepine (Carbatrol, Epitol, Equetro, Tegretol) or phenytoin (Dilantin)
• clarithromycin (Biaxin, in Prevpac)
• erythromycin (E.E.S., Erythrocin, others)
• fentanyl (Abstral, Actiq, Duragesic, Fentora, Lazanda, Onsolis, Subsys)
• lithium (Lithobid)
• medications for irregular heart beat
• medications for mental illness
• medications to treat migraines such as almotriptan (Axert), eletriptan (Relpax), frovatriptan (Frova), naratriptan (Amerge), rizatriptan (Maxalt), sumatriptan (Imitrex), and zolmitriptan (Zomig)
• methylene blue
• mirtazapine (Remeron)
• monoamine oxidase (MAO) inhibitors including isocarboxazid (Marplan), linezolid (Zyvox), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate)
• moxifloxacin (Avelox)
• selective serotonin reuptake inhibitors (SSRIs) such as citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac, Sarafem, in Symbyax), fluvoxamine (Luvox), paroxetine (Brisdelle, Paxil, Pexeva), and sertraline (Zoloft)
• tramadol (Conzip, Ultram, in Ultracet)
• apomorphine (Apokyn)

Is this medicine FDA approved?

• Ondansetron was patented in 1984 and approved for medical use in 1990.

How should this medicine be used?

Recommended dosage:

Adult Recommended Dosage:

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.

Pediatric Recommended Dosage:

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 8 hours after the first dose.
• Then administer 8 mg twice a day a day (every 12 hours) 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.

Administration:

• Ondansetron comes as a tablet, a rapidly disintegrating tablet, film, and an oral solution to take by mouth.
• The first dose of ondansetron is usually taken 30 minutes before the start of chemotherapy, 1 to 2 hours before the start of radiation therapy, or 1 hour before surgery.
• Additional doses are sometimes taken one to three times a day during chemotherapy or radiation therapy and for 1 to 2 days after the end of treatment.
• Do not chew the film.
• If you are taking the rapidly disintegrating tablet, remove the tablet from the package just before you take your dose.
• To open the package, do not try to push the tablet through the foil backing of the blister.
• Instead, use dry hands to peel back the foil backing.
• Gently remove the tablet and immediately place the tablet on the top of your tongue.
• The tablet will dissolve in a few seconds and can be swallowed with saliva.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As a tablet, a rapidly disintegrating tablet, film, and an oral solution

This medicine is available in fallowing brand namesː

• Zofran; Zofran ODT; Zuplenz

What side effects can this medication cause?

The most common side effects of this medicine include:

In prevention of chemotherapy-induced are:

• headache, malaise/fatigue, constipation, diarrhea.

In prevention of radiation-induced nausea and vomiting are:

• headache, constipation, and diarrhea.

In prevention of postoperative nausea and vomiting are:

• headache and hypoxia.

Less common, but serious side effects may include:

• Hypersensitivity Reactions
• QT Prolongation
• Serotonin Syndrome
• Myocardial Ischemia
• Masking of Progressive Ileus and Gastric Distension

What special precautions should I follow?

• Hypersensitivity reactions, including anaphylaxis and bronchospasm, have been reported in patients who have exhibited hypersensitivity to other selective 5-HT3 receptor antagonists. Discontinue ondansetron tablets if suspected. Monitor and treat promptly per standard of care until signs and symptoms resolve.
• Electrocardiogram (ECG) changes including QT interval prolongation have been seen in patients receiving ondansetron. 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.
• The development of serotonin syndrome has been reported with 5-HT3 receptor antagonists alone. If such symptoms occur, discontinue ondansetron tablets and initiate supportive treatment. If concomitant use of ondansetron tablets with other serotonergic drugs is clinically warranted, patients should be made aware of a potential increased risk for serotonin syndrome.
• The use of ondansetron tablets 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.
• Advise patients of the possibility of serotonin syndrome with concomitant use of ondansetron tablets and another serotonergic agent such as medications to treat depression and migraines. Advise patients to seek immediate medical attention if the following symptoms occur: changes in mental status, autonomic instability, neuromuscular symptoms with or without gastrointestinal symptoms.
• It is not known whether ondansetron is present in human milk. There are no data on the effects of ondansetron tablets on the breastfed infant or the effects on milk production.
• if you have phenylketonuria, you should know that the orally disintegrating tablets contain aspartame that forms phenylalanine.

What to do in case of emergency/overdose?

Symptoms of overdose may include:

• headache
• malaise/fatigue
• constipation
• diarrhea
• Sudden blindness
• constipation
• Hypotension (and faintness)
• second-degree heart block
• serotonin syndrome with symptoms somnolence, agitation, tachycardia, tachypnea, hypertension, flushing, mydriasis, diaphoresis, myoclonic movements, horizontal nystagmus, hyperreflexia, and seizure

Management of overdosage:

• In case of overdose, call the poison control helpline of your country. In the United States, call 1-800-222-1222.

• Overdose related information is also available online at poisonhelp.org/help.
• In the event that the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services. In the United States, call 911.
• There is no specific antidote for ondansetron overdose.
• Patients should be managed with appropriate supportive therapy.

Can this medicine be used in pregnancy?

• Available data do not reliably inform the association of ondansetron tablets and adverse fetal outcomes.

Can this medicine be used in children?

• The safety and effectiveness of orally administered ondansetron tablets have been established in pediatric patients 4 years and older for the prevention of nausea and vomiting associated with moderately emetogenic cancer chemotherapy.

The safety and effectiveness of orally administered ondansetron tablets have not been established in pediatric patients for:

• prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy.
• prevention of nausea and vomiting associated with radiotherapy.
• prevention of postoperative nausea and/or vomiting.

What are the active and inactive ingredients in this medicine?

Active ingredient:

• ondansetron hydrochloride

Inactive ingredients:

• microcrystalline cellulose
• croscarmellose sodium
• hypromellose, unspecified
• lactose monohydrate
• magnesium stearate
• starch, corn
• titanium dioxide
• triacetin

Who manufactures and distributes this medicine?

Distributed by:

• Sun Pharmaceutical Industries, Inc.
• Cranbury, NJ USA

Manufactured by:

• Natco Pharma Limited, Kothur, India

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F).

Antidiarrheal agents

Antidiarrheal agents include bulk forming agents, hydroscopic agents, bile acid resins, bismuth, inhibitors of intestinal motility, non-absorbed antibiotics and hormones. Bulk forming agents include methylcellulose; hydroscopic agents include pectin and kaolin; bile acid resins are cholestyramine, colestipol and colesevalam; inhibitors of intestinal motility include opioids such as diphenoxylate and loperamide. Antibiotics include rifamycin and rifaximin which are non-absorbed and are used for travelers' diarrhea. Hormones with antidiarrheal activity include octretide and somatostatin. Most antidiarrheal agents are active locally in the small intestine and colon and are largely not absorbed. Some, however, have been implicated in rare causes of liver injury (senna, cascara, cholestyramine). Telotristat is a relatively new agent that inhibits the synthesis of serotonin and is used specifically for the diarrhea of carcinoid syndrome.

• Cholestyramine
• Colesevelam
• Colestipol
• Crofelemer
• Difenoxin
• Diphenoxylate
• Kaolin
• Loperamide
• Methylcellulose
• Octreotide
• Pectin
• Rifamycin
• Rifaximin
• Somatostatin
• Telotristat

Antiemetics are a diverse group of medications that act at different points in the pathways that regulate nausea and vomiting. These include antihistamines, anticholinergic agents, phenothiazines, serotonin type 3 receptor blockers, centrally acting benzamides, cannabinoid receptor agonists, substance P antagonists and miscellaneous.

Anticholinergic Agents

• Hyoscyamine, Methscopolamine, Scopolamine

Antihistamines

• Cyclizine, Dimenhydrinate, Hydroxyzine, Meclizine, and Promethazine

Cannabinoid Receptor Agonists

• Dronabinol, Nabilone, Tetrahydrocannabinol
• Phenothiazines [See Antipsychotic Agents]
• Chlorpromazine, Prochlorperazine

Serotonin 5-HT3 Receptor Antagonists

• Alosetron, Dolasetron, Granisetron, Ondansetron, Palonosetron

Substance P/Neurokinin 1 Receptor Antagonists

• Aprepitant, Fosaprepitant, Rolapitant

Miscellaneous

• Dexamethasone, Metoclopramide, Trimethobenzamide

Acid peptic disease/antiulcer agents that include antacids, the histamine type 2 receptor blockers (H2 blockers), and the proton pump inhibitors (PPIs). These agents are some of the most commonly taken medications and are very well tolerated, most being available both by prescription and over-the-counter. While many of these drugs are approved for use in duodenal and gastric ulcer disease, their major use is for acid reflux and indigestion.

Histamine H2 Receptor Antagonists (H2 Blockers) Cimetidine, Famotidine, Nizatidine, Ranitidine

Proton Pump Inhibitors

• Dexlansoprazole, Esomeprazole, Lansoprazole, Omeprazole, Pantoprazole, Rabeprazole

Cathartics, laxatives or agents for constipation include bulk forming agents, osmotic agents, stool wetting agents, nonspecific stimulants, prokinetic agents and agents that increase fluid secretion. Many of these therapies are not systemically absorbed and none are considered particularly hepatotoxic. Naldemedine and naloxegol are opioid antagonists and are used to treat the constipation associated with opioid use.

• Bisacodyl
• Cascara Sagrada
• Castor Oil
• Docusate
• Fiber, Bran
• Lactulose
• Magnesium Sulfate
• Methylcellulose
• Naldemedine (Opioid Antagonist)
• Naloxegol (Opioid Antagonist)
• Plecanatide (for Chronic Idiopathic Constipation)
• Prucalopride (for Chronic Idiopathic Constipation)
• Senna

Inflammatory bowel disease encompasses several disorders, most commonly ulcerative colitis and Crohn colitis. Agents can be classified as 5-aminosalicyclic acid (5-ASA) based agents, immunosuppressive drugs, antitumor necrosis factor agents, corticosteroids, antibiotics and miscellaneous.

5-Aminosalicyclic Acid (5-ASA) Derivatives

• Balsalazide, Mesalamine, Olsalazine, Sulfasalazine

Immunosuppressive Agents

• Azathioprine, Mercaptopurine, Methotrexate

Tumor Necrosis Factor Antagonists

• Adalimumab, Certolizumab, Golimumab, Infliximab

Miscellaneous

• Metronidazole, Natalizumab, Vedolizumab

Irritable Bowel Syndrome Agents Antimuscarinics/Antispasmodics [See Anticholinergic agents

• Dicyclomine, Glycopyrrolate, Hyoscyamine, Methscopolamine

Prokinetic Agents - See Serotonin 5-ht4 receptor agonists Alosetron, Cisapride, Domperidone, Linaclotide, Lubiprostone, Metoclopramide, Plecanatide, Prucalopride, Tegaserod

Other

• Eluxadoline

• Dailymed label info on Ondansetron
• FDA Ondansetron

Ondansetron Resources
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