Ondansetron - Benefits, dosage and side effects

Ondansetron is a drug used to prevent and treat nausea and vomiting that can be caused by side effects of chemotherapy, radiotherapy, or surgery. This medicine should only be taken with a doctor's prescription

Ondansetron is an antiemetic (anti-nausea) which belongs to the group of serotonin receptor antagonists (5HT_{3 receptors). Serotonin is a chemical that is naturally produced by the body for various purposes. One of them is to regulate bowel movements and the digestive tract as a whole.}

In certain conditions, such as during chemotherapy, radiotherapy, or surgery, the body's serotonin levels will increase. Likewise, the amount of serotonin that binds to 5HT_{3 receptors. This can cause nausea and vomiting.}

Ondansetron works by blocking the effects of serotonin (5HT_{3). That way, the effects of nausea and vomiting in the conditions above can be overcome or even prevented.}

Ondansetron trademarks: Ceteron, Fudanton, Maxtron, Narfoz, Nausimex, Ondansetron HCl 2H20, Ondansetron HCI Dihydrate, Ondansetron Hydrochloride Dihydrate, Vometron, Zetral

What is Ondansetron?

Class	Prescription drugs
Categories	Antiemetic serotonin receptor antagonist
Benefits	Prevent and treat nausea and vomiting.
Used by	Adults and children
Ondansetron for pregnant and lactating women	Category B: Animal studies have not shown any risk to the fetus, but there have been no controlled studies in pregnant women. It is not yet known whether ondansetron can be absorbed into breast milk or not. If you are breastfeeding, do not use this medicine before consulting your doctor first.
Medicine form	Tablets, dissolving tablets, syrups, injections, and infusions

Warning Before Using Ondansetron

Pay attention to the following points before using this medicine:

• Tell your doctor if you have a history of allergies, especially to ondasentron or other serotonin-blocking drugs, such as granisetron.
• Tell your doctor if you have liver disease, indigestion, severe diarrhea or vomiting, hypokalemia, magnesium deficiency, heart failure, heart rhythm disturbances, especially prolonged cardiac QT interval on the EKG, or bradycardia.
• Tell your doctor if you have recently had surgery on your stomach or digestive tract.
• Notify your doctor if anyone in your family has a prolonged cardiac QT interval or sudden cardiac arrest.
• Tell your doctor if you plan or are taking any other medications, including supplements or herbal products.
• Tell your doctor if you are pregnant, breastfeeding, or planning a pregnancy.
• Do not drive or do activities that require alertness when taking ondansetron, because this drug can cause dizziness and drowsiness.
• Do not drink alcoholic beverages while undergoing treatment with ondansetron because it can increase the risk of side effects.
• See a doctor immediately if you have an allergic reaction or overdose.

Dosage and Rules for Using Ondansetron

The dosage of ondansetron varies, depending on the purpose of the treatment being undertaken, the dosage form of the drug, and the age of the patient. Here is the explanation:

1. Prevent nausea and vomiting due to radiotherapy

Form of medicine: Drinking medicine

Adult

• Total radiotherapy (whole body): 8 mg, taken 1-2 hours before radiotherapy.
• High-dose single abdominal radiotherapy: 8 mg, taken 1-2 hours before therapy, then every 8 hours for 1-2 days after therapy.
• Daily abdominal radiotherapy: 8 mg, taken 1-2 hours before radiotherapy, then every 8 hours during radiotherapy.

Forms of medicine: Injection and infusion

Adult

• 8 mg, injected into a vein (intravenous/IV) or muscle (intramuscular/IM) just before radio

Elderly 75 years old

• 8 mg, IV infusion over 15 minutes, may be followed by 2 further doses of 8 mg, given 4 hours and 8 hours after the initial dose.

2. Prevent nausea and vomiting due to chemotherapy

Form of medicine: Drinking medicine

Adult patients and children aged >12 years

• Chemotherapy with usual emetogenic (nausea-inducing) effects: 8 mg, given 30 minutes to 2 hours before chemotherapy, followed by 8 hours or 12 hours later as much as 8 mg.
• Chemotherapy with severe emetogenic effects: 24 mg single dose, given 30 minutes to 2 hours before chemotherapy.
• Continuation after chemotherapy is completed: 8 mg, 2 times daily, up to 5 days after chemotherapy.

Children aged 4–11 years

• Chemotherapy with usual emetogenic effect: 4 mg, given 30 minutes before chemotherapy. The same dose will be given again 4 hours and 8 hours after the initial dose.

Form of medicine: Injection or infusion

Adult

• Chemotherapy with usual emetogenic effects: 8 mg or 0.15 mg/kgBW via slow IV injection.
• Chemotherapy with severe emetogenic effects: 8 mg IV or IM injection before chemo The maintenance dose can be given by infusion at 1 mg/hour for 24 hours, or by injection of 8 mg given 4 hours and 8 hours after the initial dose.

Elderly age < 75 years

• The maximum dose is 16 mg IV infusion over 15 minutes.

Elderly aged 75 years

• Initial dose 8 mg IV infusion over 15 minutes. The follow-up dose is 8 mg given 4 hours and 8 hours after the initial dose.

Child 6 months

• 0, 15 mg/kgBW (maximum dose 8 mg) via IV infusion, given 30 minutes before chemotherapy. The dose can be repeated 4 hours and 8 hours after the initial dose.

3. Overcoming nausea and vomiting after surgery

Form of medicine: Drinking medicine

Adult

• 16 mg, given 1 hour before anesthetic administration.

Children with weight 40 kg

• 4 mg, given 1 hour before anesthetic administration. Continued dose 4 mg after 12 hours.

Form of medicine: Injection

Adult

• 4 mg, given by IV or IM injection before administration of anesthesia.

Child with weight >40 kg

• 4 mg, given by IV injection before administration The maximum dose is 4 mg per dose.

Children aged 1 month with weight≤40 kg

• 0, 1 mg/kgBB, given by IV injection before administration

How to Use Ondansetron Correctly

Ondansetron in injection and infusion forms will be given by a doctor or medical officer on the direction of a doctor.

Make sure to read the instructions on the medicine packaging and follow the doctor's advice when taking ondansetron in the form of a drink.

Ondansetron drink is available in the form of tablets, fast dissolving tablets, and syrups. This medicine can be taken before or after meals, but be sure to follow the doctor's instructions when taking it.

Ondansetron tablets need to be taken with a glass of water. Meanwhile, ondansetron in the form of fast-dissolving tablets is simply placed on the tongue and waited for it to dissolve before being swallowed with saliva.

To consume ondansetron syrup, use the measuring device provided in the package. Do not use tablespoons or teaspoons, as the dosage may be incorrect. Shake the bottle before pouring the medicine into the measuring spoon.

Ondansetron drinking usually needs to be taken about 1 hour before chemotherapy, radiotherapy, or surgery. Especially after chemotherapy, you may need to continue using this drug for a few days afterward, as directed by your doctor.

For patients who forget to take ondansetron, it is recommended to take it immediately if the break with the next consumption schedule is not too close. If it is close, ignore the dose and do not double the next dose.

Store ondansetron in a dry and cool place away from direct sunlight. Keep this medicine out of reach of children.

Ondansetron Interaction with Other Drugs

Interaction effects that can occur if ondansetron is combined with certain drugs include:

• Lower efficacy of ondansetron when used with strong CYP3A4 inducers, such as carbamazepine, phenytoin, or rifampicin
• Reduced pain relief effect of tramadol
• Increased effectiveness of ondansetron when used with dexamethasone sodium phoshate
• Increased risk of serotonin syndrome if used with selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), MAOIs, mirtazapine, fentanyl, or lithium
• Increased risk of QT prolongation or arrhythmias when used with atenolol, doxorubicin, daunorubicin, trastuzumab, erythromycin, ketoconazole, or antiarrhythmics, such as amiodarone
• Increased risk of severe hypotension and loss of consciousness when used with apomorphine.

Side Effects and Dangers of Ondansetron

Ondansetron can cause different side effects in each person. Possible side effects include:

• Headache or dizziness
• Feel like floating
• Constipation
• Fatigue and body feels weak
• Shiver
• Sleepy

Contact your doctor if these side effects don't get better or get worse. See a doctor immediately if you experience an allergic reaction to a drug or a more serious side effect, such as:

• Sight becomes blurry or vision is temporarily lost
• stomach pain
• Muscle cramps or muscle stiffness
• chest pain
• The heart beats slowly, rapidly, or irregularly
• Symptoms of serotonin syndrome, which can be characterized by palpitations, hallucinations, loss of body coordination, feeling very dizzy, fever, feeling restless or anxious, muscle twitching, and severe nausea, vomiting, and diarrhea