Rituximab

A to Z Drug Facts

Actions Rituximab is a monoclonal antibody directed against the CD20 antigen found on the surface of normal and malignant B lymphocytes. The CD20 antigen is also expressed on more than 90% of B-cell non-Hodgkin's lymphomas (NHL).

 Indications Relapsed or refractory low-grade or follicular, CD20 positive, B-cell non-Hodgkin's lymphoma.

 Contraindications IgE-mediated hypersensitivity or anaphylactic reactions to murine proteins or to any component of this product.

 Route/Dosage

Non-Hodgkin's Lymphoma

ADULTS: IV infusion Initial therapy: 375 mg/m² given once weekly for 4 or 8 doses.

Retreatment: Patients who subsequently develop progressive disease may be safely retreated with rituximab 375 mg/m² once weekly for 4 doses. Currently, there are limited data concerning more than 2 courses.

Pretreatment Regimens

ADULTS: Give acetaminophen 650 mg (PO or rectal) and diphenhydramine 25 to 50 mg (PO or IV) 30 to 60 min before administering rituximab.

Interactions No specific drug interactions have been reported. Coadministration of drugs with similar pharmacologic effects may cause additive side effects, including toxicity.

Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: Hypotension, arrhythmias, angina. CNS: Headache, dizziness, asthenia. DERMATOLOGIC: Pruritus, rash, urticaria. GI: Nausea and vomiting, abdominal pain. HEMATOLOGIC: Mild thrombocytopenia, neutropenia, anemia. RESPIRATORY: Rhinitis, bronchospasm, dyspnea. OTHER: Fever, chills, rigor, angioedema, flushing.

 Precautions

Pregnancy: Category C. Lactation: Because human IgG is excreted in breast milk and the potential for absorption and immunosuppression in the infant is unknown, advise women to discontinue nursing until circulating drug levels are no longer detectable. Children: Safety and efficacy have not been established. Severe infusion reactions and hypersensitivity reactions: Rituximab has caused severe infusion reactions. In some cases, these reactions were fatal. Interrupt the rituximab infusion for severe reactions and institute supportive care measures as medically indicated (eg, IV fluids, vasopressors, oxygen, bronchodilators, diphenhydramine, acetaminophen). Tumor lysis syndrome: Rapid reduction in tumor volume followed by acute renal failure, hyperkalemia, hypocalcemia, hyperuricemia, or hyperphosphatasemia, have been reported within 12 to 24 hr after the first rituximab infusion. Cardiac arrhythmias: Discontinue infusions in the event of serious or life-threatening cardiac arrhythmias. Renal toxicity: Rituximab administration has been associated with severe renal toxicity, including acute renal failure requiring dialysis and in some cases, has led to a fatal outcome. Severe mucocutaneous reactions: Mucocutaneous reactions, some with fatal outcome, have been reported in patients treated with rituximab. Hypersensitivity reactions: Rituximab is associated with hypersensitivity reactions (non-IgE-mediated reactions), which may respond to adjustments in the infusion rate and in medical management.

 Administration/Storage

• Do not mix or dilute rituximab with other drugs.
• Rituximab vials are stable at 2° to 8°C (36° to 46°F). Do not use beyond expiration date stamped on carton. Protect vials from direct sunlight. Refer to Preparation for information on the stability and storage of solutions of rituximab diluted for infusion. Rituximab solutions for infusion may be stored at 2° to 8°C (36° to 46°F) for 24 hr and are stable at room temperature for an additional 24 hr. However, since rituximab solutions do not contain a preservative, store diluted solutions refrigerated at 2° to 8°C (36° to 46°F).
• Withdraw appropriate dose from vial and dilute with 0.9% Sodium Chloride or 5% Dextrose to a final concentration of 1 to 4 mg/mL. Gently invert the bag to mix the solution. Discard unused portion in vial.
• Administer IV. Do not give as an IV push or bolus.

Infusion rate

• Start the initial infusion at 50 mg/hr. If no infusion reaction occurs, increase the infusion rate in increments of 50 mg/hr q 30 min up to 400 mg/hr. Subsequent infusions may be started at 100 mg/hr and increased in increments of 100 mg/hr q 30 min up to 400 mg/hr. If an infusion reaction occurred with the first dose, start subsequent infusions at 50 mg/hr.

Infusion reactions

• Slow or stop the infusion if the patient experiences a reaction. When symptoms improve, restart the infusion at 50% of the prior rate and administer the remainder of the dose.

 Assessment/Interventions

• Obtain CBC and platelet counts at regular intervals during therapy and more frequently in patients who develop cytopenias. The duration of cytopenias caused by rituximab can extend well beyond the treatment period.
• To avoid excessive infusion-related hypotension, consider avoiding antihypertensive medications for 12 hr prior to the rituximab infusion.
• Women of childbearing age should use effective contraception methods during treatment and for up to 12 mo following rituximab therapy.

 Patient/Family Education

• Explain name, action, and potential side effects of drug.
• Advise patient, family, or caregiver that medication will be prepared and administered by health care provider in a health care setting.
• Review dosing schedule with patient, family, or caregiver.
• Advise patient, family, or caregiver to immediately report any of the following to health care provider: rash; itching; hives; shortness of breath or difficulty breathing; decreased urine output; chest pain; fever, chills, or other signs of infection; sores in mouth; unusual bleeding or bruising.
• Advise patient, family, or caregiver to report any of the following to health care provider: persistent nausea, vomiting, diarrhea, or appetite loss; persistent or worsening general body weakness.
• Instruct patient to not take any prescription or OTC medications or dietary supplements unless advised to do so by health care provider.
• Instruct women of childbearing potential to notify health care provider if pregnant, planning to become pregnant, or breastfeeding.
• Advise patient that frequent follow-up visits and laboratory tests will be required to monitor therapy and to keep appointments.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts