Zofran

Zofran Uses, Dosage, Side Effects, Food Interaction and all others data.

Zofran 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.

Zofran is a highly specific and selective serotonin 5-HT3 receptor antagonist, not shown to have activity at other known serotonin receptors and with low affinity for dopamine receptors , . The serotonin 5-HT3 receptors are located on the nerve terminals of the vagus in the periphery, and centrally in the chemoreceptor trigger zone of the area postrema , . The temporal relationship between the emetogenic action of emetogenic drugs and the release of serotonin, as well as the efficacy of antiemetic agents, suggest that chemotherapeutic agents release serotonin from the enterochromaffin cells of the small intestine by causing degenerative changes in the GI tract , . The serotonin then stimulates the vagal and splanchnic nerve receptors that project to the medullary vomiting center, as well as the 5-HT3 receptors in the area postrema, thus initiating the vomiting reflex, causing nausea and vomiting , .

Moreover, the effect of ondansetron on the QTc interval was evaluated in a double-blind, randomized, placebo and positive (moxifloxacin) controlled, crossover study in 58 healthy adult men and women . Zofran was tested at single doses of 8 mg and 32 mg infused intravenously over 15 minutes . At the highest tested dose of 32 mg, prolongation of the Fridericia-corrected QTc interval (QT/RR0.33=QTcF) was observed from 15 min to 4 h after the start of the 15 min infusion, with a maximum mean (upper limit of 90% CI) difference in QTcF from placebo after baseline-correction of 19.6 (21.5) msec at 20 min . At the lower tested dose of 8 mg, QTc prolongation was observed from 15 min to 1 h after the start of the 15-minute infusion, with a maximum mean (upper limit of 90% CI) difference in QTcF from placebo after baseline-correction of 5.8 (7.8) msec at 15 min . The magnitude of QTc prolongation with ondansetron is expected to be greater if the infusion rate is faster than 15 minutes . The 32 mg intravenous dose of ondansetron must not be administered . No treatment-related effects on the QRS duration or the PR interval were observed at either the 8 or 32 mg dose .

An ECG assessment study has not been performed for orally administered ondansetron . On the basis of pharmacokinetic-pharmacodynamic modelling, an 8 mg oral dose of ondansetron is predicted to cause a mean QTcF increase of 0.7 ms (90% CI -2.1, 3.3) at steady-state, assuming a mean maximal plasma concentration of 24.7 ng/mL (95% CI 21.1, 29.0) . The magnitude of QTc prolongation at the recommended 5 mg/m2 dose in pediatrics has not been studied, but pharmacokinetic-pharmacodynamic modeling predicts a mean increase of 6.6 ms (90% CI 2.8, 10.7) at maximal plasma concentrations .

Trade Name Zofran
Availability Prescription only
Generic Ondansetron
Ondansetron Other Names Ondansetron
Related Drugs hydroxyzine, lorazepam, Zofran, dexamethasone, meclizine, promethazine, diphenhydramine, Ativan, metoclopramide, Decadron
Weight 2mg/ml, 8mg, 4mg, , 0.8mg/ml, 32mg/50ml + d5%, 4ml
Type Injection, Tablet, Syrup, Tablets, Oral Solution, Solution For Injection, Injectable Solution, Intravenous Solution
Formula C18H19N3O
Weight Average: 293.363
Monoisotopic: 293.152812245
Protein binding

The plasma protein binding associated with ondansetron was documented as approximately 73% .

Groups Approved
Therapeutic Class Anti-emetic drugs
Manufacturer Glaxosmithkline, Novartis Pharmaceuticals Uk Ltd, Novartis Pharma Ag, Glaxosmithkline Manufacturing Spa
Available Country Pakistan, United Kingdom, Canada, Saudi Arabia, United States, Netherlands, Portugal, Spain, Italy, Nigeria,
Last Updated: September 19, 2023 at 7:00 am
Zofran
Zofran

Uses

Zofran is used for: 

  • Prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy
  • Prevention of nausea and vomiting associated with radiotherapy
  • Prevention of post operative nausea and vomiting

Zofran is also used to associated treatment for these conditions: Chemotherapy-Induced Nausea and Vomiting (CINV), Cholestatic pruritus, Post Operative Nausea and Vomiting (PONV), Uremic Pruritus, Radiation therapy induced nausea and vomiting, Severe Hyperemesis gravidarum

How Zofran works

Zofran is a selective antagonist of the serotonin receptor subtype, 5-HT3 .

Cytotoxic chemotherapy and radiotherapy are associated with the release of serotonin (5-HT) from enterochromaffin cells of the small intestine, presumably initiating a vomiting reflex through stimulation of 5-HT3 receptors located on vagal afferents . Zofran may block the initiation of this reflex. Activation of vagal afferents may also cause a central release of serotonin from the chemoreceptor trigger zone of the area postrema, located on the floor of the fourth ventricle . Thus, the antiemetic effect of ondansetron is probably due to the selective antagonism of 5-HT3 receptors on neurons located in either the peripheral or central nervous systems, or both .

Although the mechanisms of action of ondansetron in treating postoperative nausea and vomiting and cytotoxic induced nausea and vomiting may share similar pathways, the role of ondansetron in opiate-induced emesis has not yet been formally established .

Dosage

Zofran dosage

Prevention of chemotherapy induced nausea & vomiting (CINV):

Adult- 

  • Tablet and oral solution: The recommended adult oral dosage of Zofran is 24 mg given as three 8 mg tablets in highly emetogenic chemotherapy. In case of moderately emetogenic chemotherapy the oral dose is one 8 mg Zofran tablet or 10 ml of Zofran oral solution given twice daily.
  • Injection: The recommended i.v. dose of Zofran is a single 32 mg dose or three 0.15 mg/kg doses. A single 32 mg dose is infused over 15 minutes beginning 30 minutes before the start of emetogenic chemotherapy. Subsequent doses (0.15 mg/kg) are administered 4 and 8 hours after the first dose of Zofran.
  • Suppository: The recommended adult dose is one 16 mg suppository 1-2 hours before treatment. Zofran should be continued for upto 5 days after a course of treatment.The recommended dose is one suppository daily.

Pediatric patients- 

  • Tablet and oral solution: for pediatric patients 4 through 11 years of age the dosage is one 4 mg Zofran tablet or 5ml of Zofran solution should be administered 3 times a day for 1 to 2 days after completion of chemotherapy.
  • Injection: the dosage in pediatric patients 4 to 18 years of age should three 0.15-mg/kg doses.
  • Suppository:Not recommended.

Radiotherapy induced nausea and vomiting:

Adult- 

  • Tablet and oral solution: the recommended oral dosage is one 8mg Zofran tablet or 10ml of Zofran oral solution given 3 times daily.

Post operative nausea & vomiting (PONV):

Adult- 

  • Tablet and oral solution: The recommended dosage is 16 mg given as two 8 mg Zofran tablets or 20 ml of Zofran oral solution 1hour before induction of anesthesia.
  • Injection: The recommended I.V. dosage of Zofran for adults is 4 mg undiluted administered intravenously in not less than 30 seconds, preferably over 2 to 5 minutes, immediately before induction of anesthesia, or postoperatively if the patient experiences nausea and/or vomiting occurring shortly after surgery. Alternatively, 4 mg undiluted may be administered intramuscularly as a single injection for adults. In patients who do not achieve adequate control of postoperative nausea and vomiting following a single, prophylactic, preinduction, I.V. dose of Zofran 4 mg, administration of a second I.V. dose of 4 mg Zofran postoperatively does not provide additional control of nausea and vomiting.
  • Suppository: The recommended adult dose is one 16 mg suppository 1-2 hours before treatment. Zofran should be continued for upto 5 days after a course of treatment.The recommended dose is one suppository daily.

Pediatric patients- 

  • Injection: The recommended I.V. dosage of Zofran for pediatric patients (2 to 12 years of age) is a single 0.1-mg/kg dose for pediatric patients weighing 40 kg or less, or a single 4 mg dose for pediatric patients weighing more than 40 kg. The rate of administration should not be less than 30 seconds, preferably over 2 to 5 minutes. Little information is available about dosage in pediatric patients younger than 2 years of age.
  • Suppository: Not recommended.

Prior to IV infusion, dilute in 50 ml dextrose 5% inj or normal saline.

Side Effects

The most common adverse effects include headache, constipation, diarrhea. In chemotherapy induced nausea and vomiting rash has occurred in approximately 1% of patients receiving Zofran. Blurred vision, chest pain with or without ST segment depression, cardiac arrhythmias, hypotension and bradycardia have been rarely reported.

Toxicity

At present, there is little information concerning overdosage with ondansetron . Nevertheless, there have been certain cases of somewhat idiosyncratic adverse effects associated with particular dosages of ondansetron used .

“Sudden blindness” (amaurosis) of 2 to 3 minutes duration plus severe constipation occurred in one patient that was administered 72 mg of ondansetron intravenously as a single dose . Hypotension (and faintness) occurred in another patient that took 48 mg of oral ondansetron . Following infusion of 32 mg over only a 4-minute period, a vasovagal episode with transient second-degree heart block was observed . Neuromuscular abnormalities, autonomic instability, somnolence, and a brief generalized tonic-clonic seizure (which resolved after a dose of benzodiazepine) were observed in a 12-month-old infant who ingested seven or eight 8-mg ondansetron tablets (approximately forty times the recommended 0.1-0.15 mg/kg dose for a pediatric patient) . In all instances, however, the events resolved completely .

The safety of ondansetron for use in human pregnancy has not been established . Zofran is not teratogenic in animals . However, as animal studies are not always predictive of human response, the use of ondansetron in pregnancy is not recommended .

Zofran is excreted in the milk of lactating rats . It is not known if it is excreted in human milk, however, nursing is not recommended during treatment with ondansetron .

Insufficient information is available to provide dosage recommendations for children 3 years of age or younger .

Precaution

Hypersensitivity reactions have been reported in patients who have exhibited hypersensitivity to other 5-HT3 receptor antagonists. Zofran is not a drug that stimulates gastric or intestinal peristalsis. It should not be used instead of nasogastric suction. 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.

Interaction

In patients treated with potent inducers of CYP3A4 (i.e Phenytoin, Carbamazepine or Rifampicin), the oral clearance of Zofran was increased and Zofran blood concentrations were decreased. Data from small studies indicate that Zofran may reduce the analgesic effect of tramadol.

Food Interaction

  • Take with or without food. The absorption is unaffected by food.

Volume of Distribution

The volume of distribution of ondansetron has been recorded as being approximately 160L .

Elimination Route

Zofran is absorbed from the gastrointestinal tract and undergoes some limited first-pass metabolism . Mean bioavailability in healthy subjects, following administration of a single 8-mg tablet, was recorded as being approximately 56% to 60% . Bioavailability is also slightly enhanced by the presence of food .

Zofran systemic exposure does not increase proportionately to dose . The 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 .

Half Life

The half-life of ondansetron after either an 8 mg oral dose or intravenous dose was approximately 3-4 hours and could be extended to 6-8 hours in the elderly .

Clearance

The clearance values determined for ondansetron in various patient age groups were recorded as approximately 0.38 L/h/kg in normal adult volunteers aged 19-40 yrs, 0.32 L/h/kg in normal adult volunteers aged 61-74 yrs, 0.26 L/h/kg in normal adult volunteers aged >=75 yrs .

Elimination Route

Following oral or IV administration, ondansetron is extensively metabolised and excreted in the urine and faeces .

Pregnancy & Breastfeeding use

In pregnancy: Pregnancy category B. Reproduction studies at daily oral dose up to 10 and 30 mg/kg/day have been performed in animals and have revealed no evidence of impaired fertility harm to the fetus due to Zofran. There are, however, no adequate and well-controlled studies in pregnant women. So the drug should be used in pregnancy only if clearly needed.

In lactation: Zofran excretes in milk of lactating animals. Caution should be exercised when Zofran is administered to nursing mother.

Contraindication

Zofran is contraindicated in patients with known hypersensitivity to the drug.

Special Warning

Pediatric use: Can be given in children 1 month of age and above. 

Geriatric use: No dosage adjustment is necessary in the elderly.Dosage adjustment for patients with impaired hepatic function:

  • Tablet and Oral Solution: The total daily dose of 8 mg should not be exceeded.
  • Injection: A single maximal dose of 8 mg to be infused over 15 minutes beginning 30 minutes before the start of the emetogenic chemotherapy is recommended.
  • Suppository: Not recommended

Acute Overdose

There is no specific antidote for Zofran overdose. In addition to the adverse events, hypotension (and faintness) occurred in a patient that took 48 mg of AVONA tablets. In all instances, the events resolved completely.

Storage Condition

Store in a cool and dry place, protected from light and moisture. For suppository- Store below 25º c.

Innovators Monograph

You find simplified version here Zofran

Zofran contains Ondansetron see full prescribing information from innovator Zofran Monograph, Zofran MSDS, Zofran FDA label

FAQ

What is Zofran used for?

Zofran is used to prevent nausea and vomiting that may be caused by surgery, cancer chemotherapy, or radiation treatment.

How safe is Zofran?

Zofran may increase the risk of developing abnormal changes in the electrical activity of the heart, which can result in a potentially fatal abnormal heart rhythm. 

How does Zofran work?

Zofran works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.

What are the common side effects of Zofran?

Common side effects of Zofran are include :

  • headache.
  • constipation.
  • weakness.
  • tiredness.
  • chills.
  • drowsiness.

Is Zofran safe during pregnancy?

Zofran is safe to use during the first trimester when most women experience morning sickness.

Is Zofran safe during breastfeeding?

Zofran appears to be compatible with breastfeeding and has limited adverse effects in normal use.

Can I drink alcohol with Zofran?

Zofran and alcohol do not directly interact, Zofran has many common side effects that could be worsened by alcohol, such as drowsiness or dizziness.

Can I drive after taking Zofran ?

Zofran may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely.

When should be taken of Zofran?

The first dose of Zofran 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.

How often should Zofran be taken?

Zofran may be taken up to 3 times a day for 1 to 2 days after your chemotherapy or radiation treatment is finished. If you are taking this medication on a prescribed schedule, take it regularly in order to get the most benefit from it. To help you remember, take it at the same times each day.

How long does it take for Zofran to start working?

Zofran should start to work within 30 minutes to an hour.

Does barnd work better on an empty stomach?

Medicines generally work faster on an empty stomach, an hour before food or 2 hours after.

How long does Zofran stay in my system?

Zofran has a half-life of three to four hours in healthy adults, but this may be increased to six to eight hours in older adults.

Does Zofran build up in my system?

Taking Zofran while you are using certain other medicines can cause high levels of serotonin to build up in your body, a condition called serotonin syndrome which can be fatal.

How long can I take Zofran?

Zofran may be taken up to 3 times a day for 1 to 2 days after your chemotherapy or radiation treatment is finished. If you are taking this medication on a prescribed schedule, take it regularly in order to get the most benefit from it.

Who should not take Zofran?

You should not use Zofran if you are also using apomorphine or you are allergic to Zofran or similar medicines.

What happens if I miss a dose of Zofran?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose of Zofran?

Seek emergency medical attention.Overdose symptoms may include sudden loss of vision, severe constipation, feeling light-headed, or fainting.

What happen If I stop taking Zofran?

If you stop taking the drug suddenly or don't take it at all.You could have nausea and vomiting that's not controlled.

Does Zofran stop stomach pain?

Zofran taken at higher doses might also relieve pain.

Does Zofran stop vomiting?

Zofran is used to prevent nausea and vomiting that may be caused by surgery, cancer chemotherapy, or radiation treatment.

Does Zofran cause heart palpitations?

Zofran can cause erratic heartbeats and high serotonin levels, which may be life-threatening.

*** Taking medicines without doctor's advice can cause long-term problems.
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