Rituxan (rituximab)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved February 2006

Specific Treatments:

moderately-to severely-active rheumatoid arthritis

Therapeutic Areas

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General Information

Rituxan (rituximab) is a CD20-directed cytolytic antibody.

Rituxan is specifically indicated for the treatment of rheumatoid arthritis (RA) in combination with methotrexate in adult patients with moderately-to severely-active RA who have inadequate response to one or more TNF antagonist therapies.

Rituxan is supplied as an injection for intravenous administration. The recommended dose is Rituxan administered as two-1000 mg intravenous infusions separated by 2 weeks. Glucocorticoids administered as methylprednisolone 100 mg intravenous or its equivalent 30 minutes prior to each infusion are recommended to reduce the incidence and severity of infusion-related reactions. Subsequent courses should be administered every 24 weeks or based on clinical evaluation, but not sooner than every 16 weeks. Rituxan is given in combination with methotrexate.

Clinical Results

FDA Approval

The FDA approval of Rituxan for rheumatoid arthritis was based largely on results from the phase III 24-week pivotal REFLEX Study. The study enrolled 520 patients (499 evaluable) with active rheumatoid arthritis (RA) who had an inadequate response to at least one TNFi therapy and active disease (≥8 swollen and ≥8 tender joints). Patients were randomized to receive 2 x 1000-mg Rituxan infusion + methotrexate (MTX) or placebo + MTX. The primary end point was ACR20 at 6 months (24 weeks). At 24 weeks, patients receiving Rituxan displayed clinically and statistically significant improvements in RA signs and symptoms, including pain and disability. In patients receiving Rituxan: 51 percent achieved ACR 20, the primary endpoint of the study, versus 18 percent of placebo patients; 27 percent achieved ACR 50, versus 5 percent of placebo patients and 12 percent achieved ACR 70, versus 1 percent of placebo patients. Rituxan was also shown to reduce biologic markers of inflammation.

Side Effects

Adverse effects associated with the use of Rituxan for rheumatoid arthritis may include, but are not limited to, the following:

upper respiratory tract infection


urinary tract infection


infusion-related reactions

serious infections

cardiovascular events

The Rituxan drug label comes with the following Black Box Warning:

Infusion-Related Reactions: Rituxan administration can result in serious, including fatal, infusion-related reactions. Deaths within 24 hours of Rituxan infusion have occurred. Approximately 80% of fatal infusion reactions occurred in association with the first infusion. Monitor patients closely. Discontinue Rituxan infusion for severe reactions and provide medical treatment for Grade 3 or 4 infusion-related reactions. Severe Mucocutaneous Reactions Severe, including fatal, mucocutaneous reactions can occur in patients receiving Rituxan. Hepatitis B Virus (HBV) Reactivation: HBV reactivation can occur in patients treated with Rituxan, in some cases resulting in fulminant hepatitis, hepatic failure, and death. Screen all patients for HBV infection before treatment initiation, and monitor patients during and after treatment with Rituxan. Discontinue Rituxan and concomitant medications in the event of HBV reactivation. Progressive Multifocal Leukoencephalopathy (PML), including fatal PML, can occur in patients receiving Rituxan.

Mechanism of Action

Rituxan (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. In this setting, B cells may be acting at multiple sites in the autoimmune/inflammatory process, including through production of rheumatoid factor (RF) and other autoantibodies, antigen presentation, T-cell activation, and/or proinflammatory cytokine production.

Additional Information

For additional information regarding Rituxan or moderately-to severely-active rheumatoid arthritis, please visit https://www.rituxan.com/