Rituximab

What it is and how it works

Mechanism of Action Rituximab is a monoclonal antibody that targets the CD20 antigen expressed on the surface of pre-B and mature B-lymphocytes. Upon binding to CD20, rituximab mediates B-cell lysis. Possible mechanisms of cell lysis include complement dependent cytotoxicity (CDC) and antibody dependent cell mediated cytotoxicity (ADCC). B cells are believed to play a role in the pathogenesis of rheumatoid arthritis (RA) and associated chronic synovitis.

Mechanism class: CD20-directed Antibody Interactions

Indications

is a CD20-directed cytolytic antibody indicated for the treatment of: Adult patients with Non-Hodgkin's Lymphoma (NHL) . Relapsed or refractory, low grade or follicular, CD20-positive B-cell NHL as a single agent. Previously untreated follicular, CD20-positive, B-cell NHL in combination with first line chemotherapy and, in patients achieving a complete or partial response to a rituximab product in combination with chemotherapy, as single-agent maintenance therapy. Non-progressing (including stable disease), low-grade, CD20-positive, B-cell NHL as a single agent after first-line cyclophosphamide, vincristine, and prednisone (CVP) chemotherapy. Previously untreated diffuse large B-cell, CD20-positive NHL in combination with (cyclophosphamide, doxorubicin, vincristine, and prednisone) (CHOP) or other anthracycline-based chemotherapy regimens.

Dosage and administration (summary)

Administer only as an intravenous infusion . Do not administer as an intravenous push or bolus . RITUXAN should only be administered by a healthcare professional with appropriate medical support to manage severe infusion-related reactions that can be fatal if they occur. . The dose for adult and pediatric B-cell NHL is 375 mg/m 2 . The dose for CLL is 375 mg/m 2 in the first cycle and 500 mg/m 2 in cycles 2–6, in combination with FC, administered every 28 days . The dose as a component of Zevalin ® (ibritumomab tiuxetan) Therapeutic Regimen is 250 mg/m 2 .

Contraindications

None. None

Warnings and precautions

Tumor lysis syndrome: Administer aggressive intravenous hydration, anti-hyperuricemic agents, monitor renal function . Infections: Withhold RITUXAN and institute appropriate anti-infective therapy . Cardiac adverse reactions: Discontinue infusions in case of serious or life-threatening events . Renal toxicity: Discontinue in patients with rising serum creatinine or oliguria . Bowel obstruction and perforation: Consider and evaluate for abdominal pain, vomiting, or related symptoms . Immunizations: Live virus vaccinations prior to or during RITUXAN treatment not recommended .

Pregnancy

Pregnancy Risk Summary Based on human data, RITUXAN can cause adverse developmental outcomes including B-cell lymphocytopenia in infants exposed to RITUXAN in-utero ( see Clinical Considerations ).

Storage and supply

Store RITUXAN vials refrigerated at 2°C to 8°C (36°F to 46°F). RITUXAN vials should be protected from direct sunlight. Do not freeze or shake.

Source: Rituximab (Rituxan) — US FDA prescribing information, 2025-01-06, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.