rituximab

Action

Binds to CD20 antigen on malignant B lymphocytes; recruits immune effector functions to mediate B-cell lysis (possibly through complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity)

Availability

Injection: 10 mg/ml in 10-ml (100-mg) and 50-ml (500-mg) vials

Indications and dosages

➣ Non Hodgkin's lymphoma (NHL)

Adults: 375 mg/m² by I.V. infusion according to the following schedules:

Relapsed or refractory, low grade or follicular, CD20-positive B-cell NHL: Give weekly for four or eight doses.

Retreatment for relapsed or refractory, low grade or follicular, CD20-positive B-cell NHL: Give weekly for four doses.

Previously untreated, follicular, CD20-positive, B-cell NHL: Give on day 1 of each cycle of cyclophosphamide, vincristine, prednisolone (CVP) chemotherapy, for up to eight doses.

Non-progressing, low-grade, CD20-positive B-cell NHL, after first line CVP chemotherapy: Following completion of six to eight cycles of CVP chemotherapy, give weekly for four doses at 6-month intervals to a maximum of 16 doses.

Diffuse large B-cell NHL: Give on day 1 of each cycle of chemotherapy for up to eight infusions.

Dosage in combination with ibritumomab: On day 1, rituximab 250 mg/m² by I.V. infusion. Within 4 hours after rituximab infusion, give 5 mCi In-111 ibritumomab I.V. On days 7, 8, and 9, give rituximab 250 mg/m² by I.V. infusion and platelet-count-dependent dose of Y-90 ibritumomab I.V.

➣ Moderately to severely active rheumatoid arthritis in patients who have had an inadequate response to one or more tumor necrosis factor antagonist

Adults: Two 1,000 mg I.V. infusions separated by 2 weeks in combination with methotrexate. Give subsequent courses every 24 weeks or based on clinical evaluation, but not sooner than every 16 weeks.

➣ Chronic lymphocytic leukemia (CLL) in combination with fludarabine and cyclophosphamide (FC)

Adults: 375 mg/m² I.V. day before start of FC chemotherapy; then 500 mg/m² on day 1 of cycles 2 to 6 (every 28 days).

Off-label uses

• Waldenström's macroglobulinemia

Contraindications

• Hypersensitivity to drug, its components, or murine products

Precautions

Use cautiously in:

• history of drug allergy or sensitivity

• previous exposure to murine-based monoclonal antibodies

• high level of circulating malignant cells

• cardiac or pulmonary conditions

• pregnant or breastfeeding patients

• children.

Administration

• Follow facility policy regarding handling, administration, and disposal of chemotherapeutic drugs.

• Know that Pneumocystis jiroveci pneumonia and antiherpetic viral prophylaxis is recommended for patients with CLL during treatment and for up to 12 months following treatment, as appropriate.

• To reduce the incidence and severity of infusion reactions, premedicate patient with diphenhydramine and acetaminophen, as prescribed. In addition, for patients with rheumatoid arthritis, give I.V. methylprednisolone (or its equivalent) 30 minutes before each infusion.

• Consider withholding antihypertensive agents 12 hours before giving drug to help prevent hypotension.

• Give drug as I.V. infusion.

☞ Never give as I.V. bolus or I.V. push.

• Don't mix or dilute with other drugs.

• Dilute in dextrose 5% in water (D₅W) or normal saline solution to a concentration of 1 to 4 mg/ml. Invert bag gently to mix solution.

• Administer the first infusion at an initial rate of 50 mg/hr. If no infusion reaction occurs, increase the infusion rate in 50 mg/hr increments every 30 minutes, to a maximum of 400 mg/hr.

• If the patient tolerates the first infusion well, administer subsequent infusions at an initial rate of 100 mg/hr and increase by 100 mg/hr increments every 30 minutes to a maximum of 400 mg/hr, as tolerated.

☞ Be aware that a severe infusion reaction may occur usually after first infusion. This reaction consists of a complex of hypoxia, pulmonary infiltrates, acute respiratory distress syndrome, M.I., ventricular fibrillation, or cardiogenic shock. If such a reaction occurs, stop infusion immediately and treat appropriately.

• If hypersensitivity reaction (non-IgE-mediated) or infusion reaction that is not severe occurs, interrupt or temporarily slow infusion. When symptoms improve, infusion can continue at half of previous rate.

Adverse reactions

CNS: dizziness, headache, nervousness, hypertonia, hyperesthesia, insomnia, agitation, malaise, paresthesia, asthenia, fatigue, tremor, rigors

CV: hypotension, hypertension, peripheral edema, chest pain, tachycardia, bradycardia, angina, arrhythmias

EENT: conjunctivitis, lacrimation disorders, rhinitis, sinusitis, pharyngitis

GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, anorexia

GU: renal toxicity

Hematologic: anemia, neutropenia, leukopenia, thrombocytopenia

Metabolic: hyperglycemia, hypocalcemia

Musculoskeletal: myalgia, back pain

Respiratory: dyspnea, cough, bronchitis, bronchospasm

Skin: pruritus, rash, urticaria, flushing, dermatitis, angioedema, toxic epidermal necrolysis, Stevens-Johnson syndrome

Other: altered taste, fever, chills, pain at injection site, hypersensitivity reactions including sepsis, severe infusion reaction

Interactions

Drug-drug. Cisplatin: increased risk of renal failure

Live-virus vaccines: increased risk of infection from vaccine

Drug-diagnostic tests. Calcium, hemoglobin, neutrophils, platelets, white blood cells: decreased values

Glucose, lactate dehydrogenase: increased levels

Patient monitoring

• Monitor closely for signs and symptoms of hypersensitivity reaction.

☞ Stop drug immediately and notify prescriber if patient develops signs or symptoms of Stevens-Johnson syndrome or other severe mucocutaneous reactions (including severe rash).

☞ Monitor pulse and blood pressure throughout I.V. infusion. Stop infusion if hypotension, bronchospasm, or angioedema occurs. Then consult prescriber about restarting infusion at half of previous rate.

☞ Monitor ECG throughout infusion. Stop infusion if serious arrhythmia develops.

• Monitor CBC, blood glucose, and electrolyte levels.

• Assess for signs and symptoms of infection, including fever.

Patient teaching

☞ Tell patient to immediately report signs and symptoms of hypersensitivity reaction or severe skin reaction.

☞ Instruct patient to take his temperature daily and immediately report fever and other signs or symptoms of infection.

☞ Instruct patient to immediately report unusual bleeding or bruising.

• Advise patient to minimize GI upset by eating small, frequent servings of food and drinking plenty of fluids.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.