Active Ingredients

Ondansetron – Effect, Application & Risks


Ondansetron is an important antiemetic that belongs to the setron drug class . Ondansetron achieves its effects by causing inhibition of the 5HT3 receptors. Because of this mode of action, ondansetron is also considered a serotonin receptor antagonist. The active ingredient is sold under the trade name Zofran® and is used to treat nausea , vomiting and nausea .

What is ondansetron?

Ondansetron is an active ingredient that is used in human medicine to treat nausea, severe nausea and vomiting. It is therefore considered an antiemetic. Its effectiveness is due to its activity in the brain . There, ondansetron inhibits the so-called 5HT3 receptors, which has a direct impact on the concentration of the neurotransmitter serotonin in the brain. A mode of action that is also used with certain psychotropic drugs.

In chemistry, ondansetron is also referred to as (RS)-9-methyl-3-(2-methylimidazol-1-ylmethyl)-1,2,3,9-tetrahydrocarbazol-4-one, which has a chemical molecular formula of C 18 – corresponds to H19-N3-O. The moral mass of the drug is approximately 293.37 g/mol. Ondansetron is subject to prescription and pharmacy requirements. The medicine is usually taken orally in the form of film-coated tablets. In acute cases, an intravenous dosage form may also be indicated.

Pharmacological effect on body & organs

After taking ondansetron, the patient experiences a noticeable reduction in nausea. This inhibitory effect is due to an inhibition of the messenger substance serotonin. In addition to the feeling of hunger, serotonin also controls the activity of the gastrointestinal tract and is also an important factor in influencing the human mood. If the concentration of the messenger substance in the human body is too high, the visceral afferent vagus is activated and the vomiting center of the central nervous system (also CNS ). Ondansetron binds to the brain’s 5HT3 receptors, which are also commonly bound to by serotonin. Because the corresponding receptorsare no longer available for the messenger substance, there is an inhibition. This reduces the existing urge to vomit.

Since various cytostatics and various radiation therapies lead to a massive increase in the serotonin content, which can cause nausea, ondansetron is mainly administered to cancer patients . Ondansetron, on the other hand, is less suitable for the treatment of nausea that is not triggered by serotonin, which is why motion sickness should be treated with other preparations.

In contrast to other antiemetics, ondansetron has no effects on the histamine, muscarinic or dopamine receptors, which is why the drug is not one of the psychotropic drugs and has no significant area of ​​application for the treatment of mental illnesses.

Medicinal Application & Use for Treatment & Prevention

Ondansetron is usually given in the form of film-coated tablets for oral administration. In acute cases, the administration of an infusion solution or administration by syringe is also conceivable.

The main area of ​​application for ondansetron is cancer therapy . It is used here to combat the side effects of chemotherapy or radiation therapy. Both cause a pathogenic increase in the serotonin content, which can lead to severe nausea. Ondansetron counteracts this.

Due to the specific mode of action, which is based on the inhibition of serotonin, there is no indication for the treatment of motion sickness.

Risks & side effects

Ondansetron can lead to undesirable side effects. The intake must be completely avoided if there is a medical contraindication. This is always the case if there are specific circumstances that call into question the success of the treatment from a medical point of view (contraindication). Ondansetron should not be taken if an intolerance or hypersensitivity ( allergy ) is known. Patients suffering from cardiac arrhythmias in the form of long QT syndrome should also not take ondansetron. There is also a contraindication in the case of heart muscle weaknesses and during breastfeeding and pregnancy .

In addition, attention should be paid to potential interactions with other active ingredients. For example, ondansetron must not be taken at the same time as apomorphine , a drug used to treat Parkinson’s disease . The two active ingredients lead to mutually dependent changes in effectiveness, which can lead to unmanageable risks. There is often a massive drop in blood pressure , which can even lead to fainting .

In addition, ondansetron is known to interact with the drugs phenytoin , carbamazepine and rifampicin . Simultaneous intake should also be avoided here. Furthermore, ondansetron leads to a reduced effectiveness of the painkiller tramadol , so that other pain-relieving preparations may have to be used.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.