Other brands/names

Degrani, Gravomit, Gramet, Kytril, Granitron, Granopi, Gramet, Granon, Granesis, Emegran, and Ganion

Mechanism of Action

Granisetron is a member of the 5HT3 serotonin antagonist class, which functions by inhibiting serotonin, a natural chemical compound in the body that can induce nausea and vomiting. Chemotherapy, radiotherapy, or surgery will result in an increase in serotonin levels.

Granisetron functions by blocking the interaction of serotonin with 5HT3 receptors in the intestines and brain, resulting in a reduction in nausea and cessation of the urge to vomit. Granisetron is a highly potent and specific anti-emetic medication that effectively blocks the 5HT3 receptor. This drug mainly works by decreasing the activity of the vagus nerve, which is in charge of activating the emetic center in the brainstem (medulla oblongata).

Indications

Nausea and vomiting are common and uncomfortable side effects experienced by cancer patients receiving chemotherapy. Granisetron is prescribed as an antiemetic to prevent and relieve symptoms of nausea and vomiting that may occur as a result of chemotherapy, radiotherapy, or post-surgical procedures. This medication is only administered upon receiving a prescription from a medical practitioner.

Contraindications

People with allergies (hypersensitivity) to granisetron or other substances present in the granisetron drug should avoid from using this medication.

Side Effects

Granisetron may induce numerous adverse effects. Side effects that are uncommon include:

• Blurred vision
• Fever
• Anxiety
• Fluctuations of heart rate
• Arm, back, or jaw pain
• Chest pain
• Feels tight in the chest
• Confusion
• Lightheadedness
• Pale 
• Nauseous
• Reddish skin
• Itchy rash
• Sweating

Meanwhile, the most commonly seen side effects are:

• Abdominal pain
• Diarrhea
• Constipation
• Headache
• Weakness
• Power loss
• Unusual fatigue

Preparations

Granisetron is available in both tablet and injectable formulations. The ampoule preparation of the injection contains Ganisetron at concentrations of 1 mg/mL and 3 mg/mL. Each oral tablet preparation contains 1 mg of Granisetron.

Dosage

• The recommended dosage of Granisetron for the treatment or prevention of postoperative nausea and vomiting is as follows: In adults, Granisetron is administered intravenously at a dosage of 1 mg over a period of 30 seconds before anesthesia. The administration can be repeated up to a maximum of 3 mg within a 24-hour period.
• The recommended dosage of Granisetron for the treatment of nausea and vomiting caused by cancer chemotherapy and radiotherapy is as follows: Granisetron can be administered intravenously or orally, in tablet form.
• The recommended intravenous dosage for adults is 1-3 mg, administered 5 minutes before to the start of chemotherapy or radiotherapy. An additional dose may be administered after a minimum of 10 minutes. The maximum allowable daily dosage is 9 mg.
• The recommended intravenous injection dose for children aged 2–16 years is 10–40 mcg per kilogramme of body weight, with a maximum dose of 3000 mcg. This should be administered via infusion over a period of 5 minutes before to the start of chemotherapy or radiotherapy. Subsequent administrations can be administered during a 24-hour period, with a minimum interval of 10 minutes following the initial infusion.
• The recommended dosage for adults is 2 mg of oral tablets, administered one hour before to the initiation of chemotherapy or radiotherapy. This initial dose should be followed by a daily maintenance dose of 2 mg, either as a single dose or divided into two doses, until one week following the completion of chemotherapy. The maximum daily dosage should not surpass 9 mg.

Safety of Drugs

Pregnancy:

Granisetron is classified as FDA Category B, indicating that animal studies have not shown any evidence of foetal risk. However, there is a lack of appropriate studies in pregnant women.

Breastfeeding:

The impact of granisetron on breast milk is uncertain, thus, it is necessary for breastfeeding mothers to seek consultation with a doctor before using it.

Drug Interactions

Granisetron may interact with other medicines, leading to various drug interactions.

• Phenobarbital can enhance the effects of granisetron
• Combining this medication with serotonergic medicines, including SSRIs, SNRIs, lithium, sumatriptan, antidepressants, or opioids such as tramadol, can increase the risk of serotonin syndrome
• Using this medication in combination with quinidine, amisulpride, or amiodarone may heighten the likelihood of experiencing heart rhythm disturbances, also known as arrhythmias
• Concurrent use of a CYP enzyme inducer or inhibitor will result in the elimination of granisetron from the body

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