How does ondansetron work to prevent nausea and vomiting. What are the common side effects of ondansetron. When should ondansetron be taken for maximum effectiveness. Who should avoid taking ondansetron. How long does it take for ondansetron to start working.

Understanding Ondansetron: An Overview of the Anti-Nausea Medication

Ondansetron, commonly known by its brand name Zofran, is a powerful anti-emetic medication used to prevent and treat nausea and vomiting. This drug belongs to a class of medications called serotonin 5-HT3 receptor antagonists, which work by blocking the action of serotonin, a natural substance in the body that can trigger nausea and vomiting.

Ondansetron is available in various forms, including tablets, orally disintegrating tablets (ODT), oral solution, and injectable formulations. The ODT form, also known as Zofran ODT, is particularly convenient for patients who have difficulty swallowing pills or those who experience sudden onset of nausea.

How does ondansetron work?

Ondansetron works by selectively blocking serotonin receptors in the brain and gut. By inhibiting these receptors, it prevents the transmission of signals that trigger nausea and vomiting. This mechanism of action makes ondansetron highly effective in managing various types of nausea and vomiting, including those associated with chemotherapy, radiation therapy, and post-operative recovery.

Primary Uses of Ondansetron: From Cancer Treatment to Motion Sickness

Ondansetron has a wide range of applications in medical practice. Its versatility makes it a valuable tool in managing nausea and vomiting across various conditions and situations.

• Chemotherapy-induced nausea and vomiting (CINV)
• Radiation therapy-induced nausea and vomiting
• Postoperative nausea and vomiting (PONV)
• Severe morning sickness in pregnant women (hyperemesis gravidarum)
• Gastroenteritis-related nausea and vomiting
• Motion sickness

Is ondansetron effective for all types of nausea? While ondansetron is highly effective for many causes of nausea and vomiting, its efficacy can vary depending on the underlying cause. It is particularly effective for CINV and PONV but may be less effective for nausea caused by vestibular disorders or certain gastrointestinal conditions.

Dosage and Administration: How to Take Ondansetron Correctly

The correct dosage of ondansetron depends on several factors, including the patient’s age, weight, medical condition, and the specific form of the medication being used. It’s crucial to follow the prescribing physician’s instructions or the guidelines provided on the medication label.

Typical dosage for adults:

• For prevention of CINV: 8 mg taken 30 minutes before chemotherapy, followed by 8 mg 12 hours later
• For prevention of PONV: 16 mg taken 1 hour before anesthesia
• For treatment of established nausea and vomiting: 4 mg or 8 mg every 8 hours as needed

How should ondansetron ODT be taken? Ondansetron ODT (orally disintegrating tablets) should be placed on the tongue and allowed to dissolve without chewing. It can be taken with or without water. For best results, it should be taken on an empty stomach, about 1 hour before or 2 hours after meals.

Side Effects and Precautions: What to Watch Out For

While ondansetron is generally well-tolerated, like all medications, it can cause side effects in some individuals. It’s important to be aware of these potential side effects and to report any severe or persistent symptoms to a healthcare provider.

Common side effects:

• Headache
• Constipation
• Feeling flushed or warm
• Dizziness
• Fatigue

Serious side effects (rare but require immediate medical attention):

• Irregular heartbeat
• Chest pain
• Shortness of breath
• Severe dizziness or fainting
• Signs of an allergic reaction (rash, itching, swelling, severe dizziness, difficulty breathing)

Can ondansetron cause long-term side effects? While most side effects of ondansetron are short-term and resolve after discontinuing the medication, there is limited data on long-term use. Some studies suggest a potential link between ondansetron use during pregnancy and a slight increase in birth defects, but more research is needed to confirm this association.

Drug Interactions: Understanding Potential Risks

Ondansetron can interact with various medications, potentially altering its effectiveness or increasing the risk of side effects. It’s crucial to inform your healthcare provider about all medications, supplements, and herbal products you are taking before starting ondansetron.

Notable drug interactions:

• Apomorphine: Can cause severe hypotension and loss of consciousness
• QT-prolonging drugs: Can increase the risk of irregular heart rhythms
• Tramadol: May reduce the pain-relieving effects of tramadol
• Rifampicin: Can decrease the effectiveness of ondansetron
• SSRIs and SNRIs: May increase the risk of serotonin syndrome

Does ondansetron interact with alcohol? While there is no direct interaction between ondansetron and alcohol, consuming alcohol can worsen nausea and vomiting, potentially counteracting the effects of ondansetron. It’s generally advisable to avoid alcohol while taking this medication.

Special Populations: Considerations for Pregnancy, Breastfeeding, and Pediatric Use

The use of ondansetron in special populations requires careful consideration and should be done under close medical supervision.

Pregnancy:

Ondansetron is classified as Pregnancy Category B by the FDA, meaning animal studies have not shown a risk to the fetus, but there are no adequate studies in pregnant women. It is sometimes used to treat severe morning sickness (hyperemesis gravidarum) when the potential benefits outweigh the risks.

Breastfeeding:

Small amounts of ondansetron can pass into breast milk. While no adverse effects have been reported in nursing infants, it’s important to discuss the risks and benefits with a healthcare provider before using ondansetron while breastfeeding.

Pediatric use:

Ondansetron is approved for use in children as young as 4 years old for the prevention of CINV. The dosage is typically based on the child’s weight or body surface area.

Is ondansetron safe for children under 4 years old? The safety and efficacy of ondansetron in children younger than 4 years have not been established. Off-label use in younger children should be done with caution and only under the guidance of a pediatric specialist.

Alternatives to Ondansetron: Exploring Other Anti-Nausea Options

While ondansetron is highly effective for many patients, there are situations where alternative anti-nausea medications may be preferred or necessary. These alternatives may be used when ondansetron is contraindicated, ineffective, or unavailable.

Common alternatives to ondansetron include:

• Granisetron (Kytril): Another 5-HT3 receptor antagonist with similar efficacy
• Palonosetron (Aloxi): A newer 5-HT3 receptor antagonist with a longer duration of action
• Metoclopramide (Reglan): A dopamine antagonist that also increases gastrointestinal motility
• Promethazine (Phenergan): An antihistamine with anti-nausea properties
• Dexamethasone: A corticosteroid often used in combination with ondansetron for CINV

How do these alternatives compare to ondansetron in terms of efficacy? The effectiveness of these alternatives can vary depending on the cause of nausea and individual patient factors. For CINV, newer 5-HT3 receptor antagonists like palonosetron have shown comparable or slightly superior efficacy to ondansetron in some studies. For other types of nausea, the choice of medication depends on the underlying cause and patient-specific considerations.

Ondansetron in Clinical Practice: Current Trends and Future Directions

Ondansetron has become a mainstay in the management of nausea and vomiting across various medical specialties. Its widespread use has led to ongoing research into its potential applications and long-term effects.

Current trends in ondansetron use:

• Increased use in emergency departments for undifferentiated nausea and vomiting
• Growing off-label use for morning sickness in pregnancy
• Exploration of its potential in treating opioid-induced nausea and vomiting
• Investigation of its efficacy in managing nausea associated with migraines

Future directions:

Ongoing research is exploring new formulations of ondansetron, including long-acting preparations and novel delivery methods. Additionally, studies are investigating the potential use of ondansetron in other conditions, such as irritable bowel syndrome and alcohol use disorder.

What new developments can we expect in anti-nausea medications? Future anti-nausea medications may target multiple receptor types simultaneously or utilize advanced drug delivery systems for more precise and prolonged effect. Personalized medicine approaches, considering genetic factors that influence drug metabolism and response, may also play a role in optimizing anti-nausea therapy.

In conclusion, ondansetron remains a crucial tool in the management of nausea and vomiting across various medical conditions. Its effectiveness, relatively good safety profile, and versatility make it a valuable option for many patients. However, as with any medication, its use should be carefully considered in light of individual patient factors, potential side effects, and alternative treatment options. Ongoing research continues to refine our understanding of ondansetron’s optimal use and explore new possibilities for improving the management of nausea and vomiting in diverse patient populations.

Ondansetron (Generic for Zofran, Disintegrating Oral Tablet)

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Ondansetron for sickness | Patient

Ondansetron for nausea and vomiting

Setofilm, Zofran

In this article

• About ondansetron
• Before taking ondansetron
• How to take ondansetron
• Getting the most from your treatment
• Can ondansetron cause problems?
• How to store ondansetron
• Important information about all medicines

About ondansetron

Ondansetron is an anti-sickness medicine, also known as an antiemetic. It is a serotonin receptor antagonist. It is prescribed to stop you from feeling sick (nauseated). It works by blocking the effect of a naturally produced chemical in your body, called serotonin. Serotonin is also referred to as 5HT₃.

Chemotherapy, radiotherapy and surgery can all cause the release of an increased amount of serotonin in your body. There are tiny areas in your small intestine and brain called 5HT₃ receptors. Serotonin acts on these receptors and causes you to feel sick. Ondansetron works by blocking serotonin from acting on the receptors, and this stops you from feeling sick or being sick (vomiting).

Before taking ondansetron

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking ondansetron it is important that your doctor knows:

• If you are pregnant or breastfeeding.
• If you have any problems with the way your liver works.
• If you have been told you have an irregular heartbeat.
• If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
• If you have ever had an allergic reaction to a medicine.

How to take ondansetron

• Before you start the treatment, read the manufacturer’s printed information leaflet from inside the pack. It will give you more information about ondansetron, and it will also provide you with a full list of the side-effects which you could experience from taking it.
• Take ondansetron exactly as your doctor tells you to. The way you have been told to take it will depend upon the reason why you are taking it:
• If you are due to have a chemotherapy or radiotherapy treatment that could cause you to feel sick, your doctor will prescribe you a dose of ondansetron to take an hour or so before the treatment. You will then be asked to continue to take ondansetron for up to five more days – tablets and liquid medicine are usually prescribed to take twice daily (every 12 hours), whereas suppositories are inserted just once daily.
• If you are being prescribed ondansetron because you are due to have surgery, you will be given a dose to take shortly before the operation.
• Ondansetron can also be given by injection. If this is the treatment prescribed for you, a doctor or nurse will administer the injections to you.
• If you have been prescribed a melt-in-the-mouth (orodispersible) medicine, these are designed to dissolve very quickly in your mouth when you put them on the top of your tongue. It helps to have a few sips of water before taking your medicine so that your mouth is moist:
• Zofran® Melt: take out a tablet from the packaging – the tablets are quite fragile so you need to peel off the foil rather than try to push the tablet through it. Place the tablet on the top of your tongue and allow it to dissolve there for a few moments before you swallow.
• Setofilm®: slowly open the sachet at the tear tag, do not use scissors to cut it. Using dry fingers, remove the film from the sachet, taking care not to damage it. Place the film on your tongue where it should dissolve in a few seconds.

How to use ondansetron suppositories

1. Remove the suppository from the wrapping.
2. You may find that inserting the suppository is easier if you squat or bend forward.
3. Using a finger, gently push the suppository into your back passage (rectum).
4. Remove your finger and then remain still for a little while to help you hold the suppository in place.
5. Then, wash your hands.

Getting the most from your treatment

• Ondansetron should start to work within an hour or so. If you are taking tablets or liquid medicine and you are sick (vomiting) within one hour of taking a dose, you should take the same dose again. This does not apply, however, if you are using suppositories or if you have been given an injection, as being sick will not prevent these from being absorbed by your body.
• Even if you do not feel like eating or drinking, try to sip water regularly to prevent you from becoming lacking in fluids (dehydrated). Also, rather than trying to eat three main meals a day, try eating small, simple but nourishing snacks, every few hours.

Can ondansetron cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with ondansetron. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer’s printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer’s information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.

How to store ondansetron

• Keep all medicines out of the reach and sight of children.
• Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

• Manufacturer’s PIL, Zofran® Tablets 4 mg, 8 mg; Novartis Pharmaceuticals UK Ltd The electronic Medicines Compendium. Dated April 2021.

• Manufacturer’s PIL, Zofran® Melt 4 mg, 8 mg; Novartis Pharmaceuticals UK Ltd, The electronic Medicines Compendium. Dated April 2021.

• Manufacturer’s PIL, Ondansetron 4 mg/5 ml oral solution; Transdermal Ltd, The electronic Medicines Compendium. Dated February 2022.

• Medicines Complete BNF 85th Edition; British Medical Association and Royal Pharmaceutical Society of Great Britain, London.

Zofran instructions, price in pharmacies of Ukraine The drug contains the active component ondansetron, a selective blocker of serotonin 5HT3 receptors. The drug may show an anti-diabetic effect. The mechanism of drug administration until the end of the term, it is therapeutically effective for the drug due to the influence of serotonin 5HT3 receptors in the central and peripheral nervous system, stimulation of these receptors during chemotherapy, which improves serotonin.

The drug does not have a sedative effect and does not affect plasma prolactin levels.

After oral administration, the drug is well absorbed in the intestinal tract. For ondansetron, the characteristic effect is the first passage through the liver. The peak plasma concentration of the active ingredient is observed 1.5 years after oral ingestion of the drug and 6 years after rectal ingestion. When taking the drug at once, the bioavailability of ondansetron is increased.

Metabolized in the liver, excreted most importantly in the presence of metabolites, about 5% of the drug is excreted in the unchanged form.

The period of administration of the drug is 3 years, in patients with a frail age – 5 years, after rectal ingestion of the drug – close to 6 years (as a result of greater absorption of the drug in the rectum). In patients with severe impairment of function, the period of drinking increases to 15-20 years.

The pharmacokinetics of the drug is the same for single and repeated doses.

In patients with impaired function, the systemic clearance and the volume of distribution of the active ingredient are reduced. The period of administration in patients with impaired blood function and creatinine clearance of 15 to 60 ml / hv reaches 5.4 years.

In patients who are on hemodialysis, the pharmacokinetics of the drug are similar to those in patients with normal functioning of the drug.

In patients with severely impaired liver function, a decrease in systemic clearance of the active component of the drug, an increase in the period of ingestion (15-32 years) and oral bioavailability (100%) are indicated.

In women, systemic clearance and volume of ondansetron was lower, lower in humans.

Indications before congestion:

The drug is indicated for the treatment and prevention of vomiting in patients who are undergoing a course of cytostatic chemotherapy or radiotherapy.

The drug is also prescribed for the prevention and treatment of nausea and vomiting in patients who have undergone surgery. For the therapy of patients in the postoperative period, do not stop the drug Zofran in the form of suppositories.

Injection method:

Injection retailer

Prescription drug for parenteral infusion. The ampoule with the preparation should be taken out without delay before the infusion, in case, even though not all of the varieties are broken, I decide to dispose of it. Ready rozchin for infusion introduction is allowed to be taken at a temperature of 2 to 8 degrees Celsius for a duration of not more than 24 years. The drug in a dose of 8 mg and less is allowed to be administered intravenously, intravenously and at the same time as intravenous infusion. If the dose is higher than 8 mg, then the drug should be administered only in case of intravenous infusion. Intravenously, the drug should be injected regularly at the upper upper quadrant of the sydnychny m’yaza.

For preparation of a brand for internal infusion as a retailer, a variety is allowed:

• 0.9% sodium chloride brand;
• Ringer’s rozchin;
• 10% manitol;
• 5% glucose solution;
• 0. 3% potassium chloride and 0.9% sodium chloride;
• 0.3% potassium chloride and 5% glucose. 0.9% sodium chloride, as well as the drug in other total sizes for intravenous administration is stable in polypropylene syringes.

  One-hour injection of a drug with a concentration of 16 to 160 µg / ml (8 mg / 500 ml and 8 mg / 50 ml) through a Y-shaped injector is allowed:

  • ia 0.48 mg / ml) for 1-8 years;
  • 5-fluorouracil (concentration 0.8 mg/ml) with a dose not exceeding 20 ml per year;
  • Carboplatin (concentration 0.18-9.9 mg / ml) with a stretch of 10-60 strands;
  • Etoposide (concentration 0.14-0.25 mg/ml) 30-60 strands;
  • Ceftazidime (dose 250-2000mg), administered in water for injection according to the recommended instructions, stretching 5 strands at a time of intravenous bolus injection;
  • Cyclophosphamide (dose 100-1000mg) is varied in water for injections according to the recommended instructions, with a stretch of 5 strands at the same time as an internal bolus injection;
  • Doxorubicin (dose 10-100mg) is administered in water for injections according to the recommended instructions, with a stretch of 5 strands at a glance for internal bolus injections;
  • The drug can also be mixed in the same urticaria with dexamethasone phosphate sodium sill (dose of ondansetron in a range of 8 µg/ml up to 1 mg/ml, dose of dexamethasone phosphate in a range of 32 µg/ml up to 2. 5 g/ml) entry hour 50- 100ml rozchin not less than 15 quills.

  The validity of the course of treatment and the dose of the drug is determined by the drug individually for the skin patient.

  Older, if you want to take a course of chemotherapy or radiotherapy, with nausea and vomiting, prescribe a proper injection of 8 mg of the drug before the start of therapy. In times like nudota or vomit, try for more than 24 years after the start of therapy, patients are prescribed the drug Zofran in medicinal forms for oral or rectal congestion.

  Let’s grow up, if you want to avoid therapy with highly methogenic drugs, in case of nausea and vomiting, prescribe a proper injection of 8 mg of the drug before chemotherapy. The dose of the drug should be increased as a fallow drug (maximum dose 32 mg) and administered as an intravenous infusion.

  In addition, during therapy with highly methogenic drugs, patients may be given the administration of ondansetron according to the regimen: 8 mg intravenously before chemotherapy, after which 2 repeated administrations of 8 mg of the drug with an interval of 2-4 godini. It is also possible to recognize ondansetron for intravenous infusion of 1 mg/year for 24 years.

  To improve the effectiveness of the drug, a single intravenous injection of 20 mg of dexamethasone phosphate sodium salt is given to current patients before chemotherapy on the cob.

  In times of nausea or vomiting, try for more than 24 years after the beginning of therapy, patients are prescribed the drug Zofran in medicinal forms for oral or rectal congestion.

  Children should be given an intravenous dose of 5 mg/m2 before chemotherapy. After 12 years after parenteral administration, the drug should be administered orally 4 mg of ondansetron 2 times a day. The oral form of the drug should be taken for 5 days after completion of the course of chemotherapy.

  Let’s grow up before the operative intervention for the prevention of nausea and vomit, administer 4 mg of the drug intravenously properly or internally during the period of induction anesthesia.

  For the treatment of vomiting in the postoperative period, it is necessary to prescribe a one-time intravenous injection of 4 mg of the drug.

  For children before surgery to prevent nausea and vomiting, prescribe the drug at a dose of 0.1 mg/kg of body weight intravenously properly during the period of induction anesthesia (it is also possible to introduce the drug before or after induction anesthesia).

  For the treatment of vomit in the postoperative period, children should be prescribed a single intravenous injection of the drug at a dose of 0.1 mg/kg body weight.

  The maximum dose of the drug for children with postoperative vomiting should be 4 mg of ondansetron.

  The maximum additional dose of the drug for patients who suffer from impaired liver function is 8 mg.

  Syrup, coated tablets, lingual tablets:

  Indication for oral administration. Tablets, covered with a shell, are recommended to be taken in whole, not rotting and not touching, drinking down the necessary amount of water. It is recommended to take lingual tablets in the mouth empty until they are full (1-2 quills) after which they are swallowed. The syrup is recommended to be taken in an undiluted form, dosing the drug in the form of a syrup is carried out with the help of a special peaceful spoon, which is put into the pack at once with the bottle. The validity of the course of treatment and the dose of the drug depends on the drug individually for the skin patient.

  Older, if you want to take a course of chemotherapy or radiotherapy, with nausea and vomiting, prescribe 8 mg of the drug 1-2 years before the start of therapy. After which the drug is taken again after 12 years at a dose of 8 mg. For the prevention of piznyoї vomit, we grow up to sound, prescribe 8 mg of the drug 2 times a day. The drug should be taken for 5 days after completion of the course of chemotherapy or radiotherapy.

  Doroslimy, yakі otrimuyut therapy with highly methogenic drugs, with nausea and vomiting, prescribe 24 mg of the drug in combination with 12 mg of dexamethasone sodium sill phosphate 1-2 years before chemotherapy on the cob. For the prevention of vomit in 24 years after the first drug taken, you should prescribe 8 mg of ondansetron 2 times a day. The drug should be taken for 5 days after completion of the course of chemotherapy.

  Children should be given a parenteral drug before chemotherapy. After 12 years after parenteral administration, the drug should be administered orally 4 mg of ondansetron 2 times a day. The drug should be taken for 5 days after completion of the course of chemotherapy.

  Let’s grow up before the operative intervention for the prevention of nudity and vomit, you should prescribe 16 mg of the drug once 60 minutes before the ear of general anesthesia. For the treatment of vomiting in the postoperative period, it is recommended to stop the drug in the form of parenteral administration.

  Rectal suppositories:

  Prescription drug for rectal infusion. The validity of the course of treatment and the dose of the drug depends on the drug individually for the skin patient.

  Older, if you want to take a course of chemotherapy or radiotherapy, with nausea and vomiting, prescribe 1 suppository of the drug 1-2 years before the start of therapy. For the prevention of vomit in adulthood, prescribe 1 suppository of the drug 1 time per day.

  The drug should be given for 5 days after completion of the course of chemotherapy or radiotherapy.

  As soon as possible, if you want to avoid therapy with highly methogenic drugs, in case of nausea and vomiting, prescribe 1 suppository of the drug 1-2 years before the start of chemotherapy. To enhance the therapeutic effect of the drug, a single intravenous injection of 20 mg of dexamethasone phosphate sodium salt is prescribed before the start of chemotherapy.

  Let’s grow up for the prevention of vomiting in 24 years after the first drug taken, prescribe 1 suppository of the drug 1 time per day. The preparation should be taken for 5 days after completion of the course of chemotherapy.

  Ondansetron film-coated tablets 8 mg PJSC SPC “Borshchagovsky CPP”

  schema.org/SiteNavigationElement”>
  • Pharmacological properties
  • Readings
  • Contraindications
  • Overdose
  • Adverse reactions
  • Expiry date
  • Storage conditions
  • Diagnosis
  • Recommended alternatives
  • Trade names

  Composition:

  active ingredient: ondansetron;

  1 tablet contains ondansetron hydrochloride dihydrate (in terms of ondansetron) 4 mg or 8 mg;

  excipients: pregelatinized starch, lactose monohydrate, microcrystalline cellulose, magnesium stearate;

  film coat: hydroxypropyl methylcellulose, copovidone, polyethylene glycol, medium chain triglycerides, polydextrose, titanium dioxide (E 171), iron oxide red (E 172), iron oxide yellow (E 172).

  Dosage form

  Film-coated tablets.

  Basic physical and chemical properties: tablets are round, biconvex surface, film-coated from yellow to brown-yellow.

  Pharmacotherapeutic group

  Antiemetics and anti-nausea drugs. Antagonists of 5HT ₃ serotonin receptors.

  ATX code A04A A01.

  Pharmacological properties

  Pharmacodynamics.

  Ondansetron is a potent, highly selective 5HT ₃ (serotonin) receptor antagonist. The drug prevents or eliminates nausea and vomiting caused by cytotoxic chemotherapy and / or radiation therapy, as well as postoperative nausea and vomiting. The mechanism of action of ondansetron has not been fully elucidated. It is possible that the drug blocks the occurrence of a gag reflex, showing an antagonistic effect on 5HT ₃ receptors, which are localized in neurons of both the peripheral and central nervous systems. The drug does not reduce the psychomotor activity of the patient and does not have a sedative effect.

  Pharmacokinetics.

  After oral administration, ondansetron is completely absorbed by passive absorption from the gastrointestinal tract and undergoes primary metabolism. Approximately 1.5 hours after the use of the drug, plasma concentration reaches a maximum. Doses greater than 8 mg increase the systemic exposure of ondansetron to a greater extent than proportionally distributed doses. This may be a sign of a reduction in primary metabolism at high oral doses.

  Ondansetron is cleared from the systemic circulation by multiple enzymatic metabolism, primarily in the liver. Less than 5% of the drug is excreted unchanged in the urine. The distribution of ondansetron when administered orally, intramuscularly or intravenously is the same: the half-life is approximately 3 hours (in elderly patients – 5 hours), the volume of distribution when equilibrium concentration is reached is almost 140 liters. Binding to plasma proteins – 70-76%. In patients with moderate renal insufficiency (creatinine clearance 15-60 ml / min), both systemic clearance and volume of distribution of ondansetron are reduced, resulting in a slight and clinically insignificant increase in the half-life of the drug. The pharmacokinetics of ondansetron practically does not change in patients with severe renal failure who are on chronic hemodialysis (studies were conducted between hemodialysis sessions). In patients with severe chronic liver failure, the systemic clearance of ondansetron decreases markedly with an increase in the half-life (15-32 hours). The absence of the CYP2D6 enzyme does not affect the pharmacokinetics of ondansetron. The pharmacokinetic properties of ondansetron do not change with repeated use. Bioavailability of oral ondansetron and half-life are clinically slightly increased in elderly patients.

  In women, the absorption of the oral dose was faster and to a greater extent, and the systemic clearance and volume of distribution were less.

  The bioavailability of the drug with food is slightly higher, but antacids do not affect the bioavailability.

  Clinical characteristics

  Indications

  Prevention and treatment of nausea and vomiting caused by cytotoxic chemotherapy or radiotherapy. Prevention of nausea and vomiting in the postoperative period.

  Contraindications

  • Hypersensitivity to the components of the drug and to other selective 5HT antagonists ₃ serotonin receptors;
  • concomitant use with apomorphine;
  • severe hepatic impairment;
  • abdominal surgery.

  Interaction with other drugs and other forms of interaction.

  Ondansetron does not accelerate or inhibit the metabolism of other drugs when used concomitantly. Special studies have shown that ondansetron does not interact with ethanol , temazepam , furosemide, alfentanil, morphine, lidocaine, thiopental or propofol .

  Ondansetron is metabolized by the hepatic cytochrome P459 enzyme system: CYP3A4, CYP2D6 and CYP1A2. Due to the diversity of enzymes of ondansetron metabolism, inhibition or a decrease in the activity of one of them (for example, a genetic deficiency of CYP2D6) is normally compensated by other enzymes and will not have an effect on the overall clearance of ondansetron or this effect will be insignificant.

  Phenytoin , carbamazepine and rifampicin: when treated with potential CYP3A4 inducers (e.g. phenytoin , carbamazepine and rifampicin ) the clearance of ondansetron increases and its concentration in the blood decreases.

  Tramadol: In a small number of clinical studies, ondansetron may reduce the analgesic effect.

  Apomorphine: concomitant use is contraindicated because cases of severe arterial hypotension and loss of consciousness have been observed.

  QT interval prolonging drugs: additional prolongation of the QT interval is possible.

  Cardiotoxic drugs (eg anthraccyclines): possible increased risk of arrhythmias.

  Serotonergics (eg SSRIs and SNRIs). Serotonin syndrome (including changes in mental status, autonomic instability and neuromuscular disorders) has been described after the simultaneous use of ondansetron and other serotonergic drugs, incl. selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) (see section “Peculiarities of use”).

  Application features.

  Ondansetron is not effective in preventing nausea and vomiting in motion sickness.

  Cases of cross-hypersensitivity to various 5HT receptor antagonists have been described. ₃ . Therefore, in the presence of hypersensitivity to one of the 5HT ₃ receptor antagonists, a similar reaction to other antagonists may be more pronounced as a result of cross-reactions. If there is even a mild hypersensitivity reaction to one of the 5HT antagonist drugs ₃ receptors, it is not recommended to change it to another, given the possibility of enhancing the hypersensitivity reaction.

  Ondansetron increases the QT interval in a dose dependent manner. There have been reports of ventricular flutter/flicker (“torsade de pointes”) with ondansetron. Ondansetron should be avoided in patients with congenital long QT syndrome. Ondansetron should be used with caution in patients who have or may develop QT prolongation, including patients with electrolyte imbalance, congestive heart failure, bradyarrhythmias, and patients treated with other drugs that may cause QT interval prolongation or electrolyte imbalance. Hypokalemia and hypomagnesemia should be corrected before use.

  Since ondansetron reduces intestinal motility, careful monitoring of patients with signs of subacute intestinal obstruction is required when using the drug.

  In patients undergoing adenotonsillar surgery, the use of ondansetron to prevent nausea and vomiting may mask bleeding. Therefore, such patients should be closely monitored after the use of ondansetron.

  Ondansetron does not affect the cytochrome P450 system, but the use of other drugs that can affect the activity of these enzymes may lead to a change in the clearance and half-life of ondansetron.

  Children receiving ondansetron together with hepatotoxic chemotherapy drugs should be carefully monitored for possible liver dysfunction.

  Patients with impaired carbohydrate tolerance, with rare hereditary diseases such as galactose intolerance, lactase deficiency or glucose-galactose malabsorption, should not take this drug, given that the tablets contain carbohydrates, including lactose.

  After the simultaneous use of ondansetron and other serotonergic drugs, serotonin syndrome has been described (see section “Interaction with other medicinal products and other forms of interaction”). If concomitant treatment with ondansetron and other serotonergic drugs is clinically warranted, appropriate monitoring of the patient is recommended.

  Use during pregnancy or lactation.

  Women of childbearing age using ondansetron should consider using contraception.

  Based on epidemiological studies, ondansetron is suspected to cause malformations of the maxillofacial region when used during the first trimester of pregnancy. In one cohort study of 1.8 million pregnancies, ondansetron use in the first trimester was associated with an increased risk of oral clefts (3 additional cases per 10,000 women treated with ondansetron; adjusted relative risk, 1.24, (95% CI 1.03–1.48)). The available epidemiological studies of heart disease show conflicting results. Animal studies do not indicate direct or indirect harmful effects in relation to reproductive toxicity. Ondansetron should not be used during the first trimester of pregnancy.

  Breast-feeding should be discontinued during treatment with the drug.

  The ability to influence the reaction rate when driving vehicles or operating other mechanisms.

  Taking into account the possibility of developing adverse reactions from the nervous system, patients during treatment are advised to refrain from driving vehicles or other mechanisms.

  Dosage and administration.

  The drug is to be taken orally.

  When carrying out cytostatic therapy, the dosing regimen should be set individually, depending on the severity of the emetic reaction.

  Moderate emetogenic chemotherapy and radiotherapy

  Adults by mouth: Initially 8 mg 1 to 2 hours before anticancer therapy, followed by another 8 mg 12 hours later.

  To prevent late or prolonged nausea and vomiting after the first 24 hours, continue the drug at 8 mg every 12 hours for 5 days.

  For partial high-dose abdominal irradiation, administer 8 mg every 8 hours. The drug should be taken during the entire course of chemotherapy and radiation therapy, as well as 1-2 days (if necessary – 3-5 days) after its completion.

  Highly emetogenic chemotherapy

  Adults administer ondansetron 24 mg orally (simultaneously with dexamethasone phosphate) 1 to 2 hours before starting chemotherapy. For the prevention of late vomiting in the following days – 8 mg 2 times a day during the entire course of chemotherapy, as well as 5 days after its completion.

  Children. In this dosage form, the drug should not be used in children under 4 years of age. Doses for children are calculated based on body surface area or body weight. If it is necessary to use ondansetron at a dose of 2 mg, the drug should be used with the appropriate dosage or in another dosage form.

  Dosage calculation based on body surface area. Immediately prior to chemotherapy, give ondansetron (injection) as a single intravenous injection at a dose of 5 mg/m ² ; intravenous dose should not exceed 8 mg. Oral administration should begin after 12 hours and continue for up to 5 days. The total daily dose of ondansetron should not exceed 32 mg.

  Calculation of dosing by body weight. Immediately before chemotherapy, give ondansetron (injection) as a single intravenous injection at a dose of 0.15 mg/kg; intravenous dose should not exceed 8 mg. In the future, it is possible to introduce two intravenous injections at intervals of 4 hours. The total daily dose of ondansetron should not exceed 32 mg. Oral administration should begin after 12 hours and continue for up to 5 days.

  Weight	1 day	2-6 days
  10 kg	Up to 3 doses of 0.15 mg/kg IV every 4 hours	Oral 4 mg every 12 hours

  Postoperative nausea and vomiting

  Adults administer 16 mg 1 hour before anesthesia.

  The maximum daily dose of ondansetron is 32 mg, for patients with impaired liver function – 8 mg.

  For children , ondansetron injection is recommended for this indication.

  For all therapies

  Elderly patients

  There is no need to change the dosage in patients over 65 years of age.

  Patients with renal insufficiency

  There is no need to change the dosage regimen or route of administration of the drug in patients with impaired renal function.

  Patients with moderate hepatic insufficiency

  In patients with moderate hepatic impairment, the clearance of ondansetron is significantly reduced and the serum half-life is increased. In such patients, the maximum daily dose of the drug should not exceed 8 mg.

  Patients with impaired sparteine/debrisoquin metabolism

  The half-life of ondansetron in patients with impaired sparteine ​​and debrisoquin metabolism does not change. In such patients, after repeated administration, the concentration of the drug is the same as in patients with normal metabolism. Therefore, there is no need to change the dosing regimen for this group of patients.

  Children.

  Do not administer the drug in this dosage form to children under 4 years of age.

  Overdose

  Symptoms: blurred vision, constipation, arterial hypotension, vasovagal disorders with transient atrioventricular blockade. Ondansetron increases the QT interval in a dose-dependent manner. In case of overdose, ECG monitoring is recommended.

  Treatment: drug withdrawal, symptomatic and supportive therapy. The use of antiemetic measures is not recommended due to the antiemetic effect of the drug itself. There is no specific antidote.

  Adverse reactions

  Immune system: allergic reactions of immediate type, sometimes severe, including anaphylactic reactions, angioedema, anaphylactic shock, bronchospasm, vascular edema, pruritus, skin rashes, urticaria.

  Nervous system: headache, myoclonus, convulsions, movement disorders (including extrapyramidal reactions such as oculogeric crisis, dystonic reactions and dyskinesia without sustained clinical consequences), gait disturbance, chorea, restlessness, burning sensation, tongue protrusion, diplopia , depression of the central nervous system, paresthesia; dizziness, mainly during rapid intravenous administration of the drug.

  Organs of vision: transient visual disturbances (blurred vision), transient blindness, mainly during intravenous administration. In most cases, blindness resolves within 20 minutes.

  Cardiovascular: chest pain and discomfort, cardiac pain (with or without ST segment depression), arrhythmias, extrasystoles, tachycardia including ventricular and supraventricular tachycardia, atrial fibrillation, palpitations, bradycardia, arterial hypotension , arterial hypertension, prolongation of the QT interval (including flutter / flicker of the ventricles (“torsade de pointes”), a feeling of warmth, hot flashes, syncope, ECG changes.

  Respiratory system: hiccups, cough.

  Digestive tract: constipation, diarrhea, dry mouth.

  Hepatobiliary system: asymptomatic increase in liver function tests, liver failure.

  General disorders: weakness, loss of consciousness.

  These cases occur mainly in patients treated with chemotherapy drugs containing cisplatin.