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Writer's pictureAditi Majrekar

Ondem(Ondansetron)


ondansetron

Category: Antiemetic   


Introduction:


Ondansetron is an antiemetic (to prevent vomiting or nausea) medication. It functions by preventing the action of  brain chemical messenger serotonin, which result in nausea and vomiting during chemotherapy or following surgery for cancer.

Uses:


ondansetron

How To Consume:


Ondansetron should be taken as per prescribed by a doctor. There are several forms of Ondansetron available for oral administration, including tablets, films, and quickly disintegrating (dissolving) tablets. This medicine is applied to the tongue and dissolved. Unlike other tablet forms, it is not meant to be chewed or consumed.

Ondansetron can be taken with or without food.

Regular Tablet - Take with a full glass of water.

Disintegrating Tablet : Take the tablet out of its packaging, just before taking your dosage. 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. Take out the tablet gently and set it on top of your tongue right away. The tablet will dissolve in a few seconds and can be swallowed with saliva.


ondansetron


Duration Between Two Dose:


Ondansetron is taken 4mg every 6 hours when required. Maximum 20mg in 24 hours. 4mg every 6 hours when required. 

Note: Patients over 75 years of age or those with significant hepatic impairment should lower their maximum dosage to 8 mg.


Side Effects:

Some common side effects can be seen after taking ondansetron:


  • Headache

  • lightheadedness

  • dizziness

  • Drowsiness

  • Tiredness

  • constipation

  • Injection site reactions (pain, swelling, redness)

ondansetron


Drug Mechanism:


Pharmacokinetics:

Ondansetron undergoes rapid absorption from the GI tract, and the peak plasma concentration (Tmax) is approximately 1.5 hours after an 8 mg single oral dose. The absolute bioavailability of ondansetron after oral administration is approximately 60%(50%-70%). Tissues contain large amounts of ondansetron and its metabolites. The principal(main) location of metabolism is the liver. Hepatic metabolism accounts for nearly 95% of ondansetron clearance, and less than 5% is excreted unchanged in the urine. 


Pharmacodynamics: 

Ondansetron is a selective antagonist of the 5-HT3 subtype of serotonin receptors. Ondansetron prevents and treats nausea and vomiting by acting both centrally and peripherally. Central effects are mediated by the antagonism of 5HT-3 serotonin receptors in the area postrema which contain "chemoreceptor trigger zone.".  his zone senses neurotransmitters like serotonin, toxins, and other signals and plays a role in mediating the sensation of nausea and subsequent vomiting. Because ondansetron acts on the vagus nerve, it also has peripheral effects. It acts on the 5-HT3 receptors present in the terminals of the vagus nerve. The vagus nerve is sensitive to GI tract stimulants that cause nausea and vomiting. It creates connections in the brainstem's nucleus tractus solitarius, another area crucial for vomiting. Ondansetron's antiemetic effects are mostly assumed to be mediated through its peripheral activities.


Safety Measures :


ondansetron
ondansetron

When to See Doctor:

  • drowsiness and sedation,

  • fast or pounding heartbeats

  • severe constipation, stomach pain, or bloating

  • jaundice (eye or skin yellowing)

  • blurred vision or temporary vision loss

  • hallucinations (hearing voices or seeing things that are not there)excessive sweating

If conditions from this occur you should see the doctor or it can be hazardous for your health if not cured as soon as possible.


ondansetron

Allergic Reaction:

This drug can cause severe allergic reactions. Symptoms include:

  • rash

  • hives

  • itching

  • Inflammation of the hands, feet, ankles, neck, lips, eyes, or lower limbs

  • loss of coordination

  • stiff or twitching muscles

  • seizures

ondansetron


Immediately go to the doctor if these symptoms occur. 


Available Dosage Form:

Form: 

  1. Tablet 

Strengths: 4mg, 8mg

  1. Injections 

Strengths0.15 mg/kg IV (max- 16 mg per dose)

Child Dosage

Age- 4 to 11 years age

4 mg is given every 12 hours for a period of one to two days.

Age- 12 years age

8 mg is given every 12 hours for a period of one to two days.

Age- younger than 4 years of age

Use and dose must be determined by your doctor

Adult Dosage-

8 mg is given every 12 hours for a period of one to two days.


Important Note:


  • Follow the doctor's prescription for the entire course of therapy; do not miss a dosage.Take the missed dose of this medication as soon as you remember if you feel nauseated or throw up after missing one.

  • Till the time comes to use it, keep the medication in the foil packet.

  • Try to consume little, healthful snacks throughout the day instead of large, filling meals. In order to assist prevent dehydration, sip water frequently.

  • Before using this drug, disclose to your chemist or doctor any medical history you may have, particularly with regard to liver illness, irregular heartbeat, and stomach/intestinal issues (such as ileus, edoema, or recent abdominal surgery).

Various Brands:


ondansetron

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