Granisetron

Generic name: Granisetron

Drug class: 5-HT3 receptor antagonists

Dosage form: Oral tablet (1 mg), intravenous solution, transdermal patch

Root of administration: Oral, intravenous, transdermal

Dose: For chemotherapy-induced nausea and vomiting: 1 mg orally once daily, administered 1 hour before chemotherapy; a second dose may be given 12 hours later. For radiation-induced nausea and vomiting: 2 mg orally once daily, administered 1 hour before radiation therapy. For postoperative nausea and vomiting: 1 mg intravenously, administered 30 minutes before anesthesia induction. Transdermal patch: 3.1 mg applied 24 to 48 hours before chemotherapy, worn for up to 7 days. Dosage adjustments may be necessary for patients with hepatic impairment or electrolyte imbalances.

Mechanism of action: Granisetron is a selective 5-HT3 receptor antagonist that blocks serotonin, a natural substance in the body that triggers nausea and vomiting. By inhibiting serotonin at 5-HT3 receptors in the gastrointestinal tract and central nervous system, granisetron effectively prevents nausea and vomiting associated with chemotherapy, radiation therapy, and surgery.

Drug usage cases:

• Prevention of nausea and vomiting caused by chemotherapy, including high-dose cisplatin
• Prevention of nausea and vomiting associated with radiation therapy
• Prevention and treatment of postoperative nausea and vomiting
• Off-label use for nausea and vomiting due to acute or chronic medical illnesses or acute gastroenteritis
• Off-label use in the treatment of cyclic vomiting syndrome

Drug contraindications:

• Hypersensitivity to granisetron or any component of the formulation
• Concurrent use with other 5-HT3 receptor antagonists
• Known or suspected bowel obstruction
• Severe hepatic impairment
• Electrolyte imbalances, particularly low potassium or magnesium levels
• History of long QT syndrome or other significant heart rhythm disorders

Side effects:

• Common: headache, constipation, diarrhea, dizziness, sleepiness, irregular heartbeat
• Serious: allergic reactions (e.g., hives, difficulty breathing, swelling of the face, lips, tongue, or throat), chest pain, severe dizziness, fainting, fast or pounding heartbeats, increased blood pressure (e.g., severe headache, buzzing in ears, anxiety, confusion, shortness of breath), serotonin syndrome (e.g., agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting)

Warnings:

• Monitor for signs of serotonin syndrome, especially when used with other serotonergic drugs
• Use caution in patients with a history of heart disease or arrhythmias due to potential QT interval prolongation
• Assess and correct electrolyte imbalances before initiating therapy
• Monitor blood pressure regularly during treatment
• Use with caution in patients with recent abdominal or stomach surgery
• Not approved for use in individuals under 18 years old

Use during pregnancy or breastfeeding: Granisetron is classified as a pregnancy category B1 drug, indicating that it is not expected to harm an unborn baby. However, its safety during pregnancy has not been well studied. It is not known whether granisetron passes into breast milk or if it could harm a nursing baby. Therefore, it should be used during pregnancy or breastfeeding only if clearly needed and prescribed by a healthcare provider.