ORION 20mg TAB (10s)

Description

ORION 20 mg Tablet contains Ondansetron, a selective serotonin 5-HT3 receptor antagonist. It is primarily used to prevent and treat nausea and vomiting caused by chemotherapy, radiation therapy, or surgery. Ondansetron works by blocking the action of serotonin, a neurotransmitter that can trigger nausea and vomiting. It is effective in managing chemotherapy-induced nausea and vomiting (CINV), postoperative nausea and vomiting (PONV), and radiation-induced nausea and vomiting.

Therapeutic Class:

Antiemetic (Anti-nausea and Vomiting Agent)

Active Ingredient:

Ondansetron 20 mg per tablet

Indications:

ORION 20 mg Tablet is indicated for:

• Chemotherapy-induced nausea and vomiting (CINV):
  • Prevents and treats nausea and vomiting associated with chemotherapy, particularly during the early phase after chemotherapy administration.
• Postoperative nausea and vomiting (PONV):
  • Prevents and treats nausea and vomiting following surgery.
• Radiation-induced nausea and vomiting:
  • Used to prevent and treat nausea and vomiting caused by radiation therapy, especially in the treatment of head and neck cancers.

Mechanism of Action:

Ondansetron works by selectively blocking the 5-HT3 receptors in the central nervous system and the gastrointestinal tract. Serotonin, which is released from enterochromaffin cells in the gastrointestinal tract, binds to these receptors, causing nausea and vomiting. By blocking this receptor, Ondansetron prevents the initiation of the vomiting reflex. It acts both in the brain (on the chemoreceptor trigger zone) and in the gastrointestinal tract, reducing nausea and vomiting induced by chemotherapy, radiation, or surgery.

Dosage and Administration:

• Chemotherapy-induced nausea and vomiting (CINV):
  • Adults: A typical dose is 8 mg orally taken 30 minutes before chemotherapy, followed by 8 mg every 12 hours for 1-2 days after chemotherapy. For high-emetogenic chemotherapy, the dose may be adjusted as per the physician’s advice.
• Postoperative nausea and vomiting (PONV):
  • Adults: The usual dose is 16 mg orally taken 1 hour before anesthesia.
• Radiation-induced nausea and vomiting:
  • The dose is typically 8 mg orally 1-2 hours before radiation treatment, followed by 8 mg every 12 hours.
• Pediatric Dosage:
  • The dosage is based on the child’s weight and the physician’s recommendation. Generally, doses range from 0.1 mg/kg to 4 mg depending on the severity of nausea and vomiting.
• Administration:
  • The tablets should be taken whole, not chewed or crushed, with a glass of water.

Contraindications:

• Hypersensitivity to Ondansetron or any of the components of the formulation.
• Congenital long QT syndrome or electrolyte imbalances that could affect cardiac conduction (e.g., low potassium or magnesium).
• Severe hepatic impairment (e.g., cirrhosis).

Warnings and Precautions:

• QT Interval Prolongation:
  • Ondansetron can cause prolongation of the QT interval, especially when used at high doses. Caution is advised in patients with a history of arrhythmias, heart failure, or electrolyte disturbances (e.g., low potassium or magnesium).
• Hepatic Impairment:
  • In patients with severe hepatic impairment, a reduced dose of Ondansetron should be considered.
• Serotonin Syndrome:
  • While rare, the use of Ondansetron in combination with other serotonergic drugs (e.g., SSRIs, SNRIs, MAOIs) could lead to serotonin syndrome, a potentially life-threatening condition. Symptoms include confusion, agitation, fever, tremor, and muscle rigidity.
• Pregnancy and Lactation:
  • Pregnancy Category B: Ondansetron should be used during pregnancy only when the potential benefit justifies the potential risk to the fetus. Ondansetron should be used with caution in breastfeeding mothers, as it is excreted in breast milk.

Adverse Effects:

Common Side Effects:

• Headache
• Constipation
• Fatigue
• Dizziness

Serious Side Effects:

• QT Prolongation and risk of arrhythmias
• Severe allergic reactions (e.g., rash, itching, swelling)
• Hepatic toxicity (elevated liver enzymes)
• Serotonin syndrome (when used with serotonergic drugs)
• Severe constipation or bowel obstruction (rare)

Drug Interactions:

• CYP450 Enzyme Interactions: Ondansetron is metabolized via CYP3A4 and CYP2D6 enzymes, so caution should be taken when combining it with other medications that affect these enzymes (e.g., rifampin, phenytoin, or carbamazepine).
• Drugs Prolonging QT Interval: Use with other drugs that prolong the QT interval (e.g., antipsychotics, antiarrhythmic agents) can increase the risk of arrhythmias and QT prolongation.
• Serotonergic Drugs: When used in combination with other serotonergic drugs (e.g., SSRIs, SNRIs), there is an increased risk of serotonin syndrome.

Storage:

• Store at room temperature (20°C to 25°C or 68°F to 77°F).
• Keep in the original packaging to protect from moisture and light.
• Keep out of reach of children.