Rituxan (rituximab)

RITUXAN (rituximab) – a CD20-directed cytolytic antibody indicated for the treatment of patients with rheumatoid arthritis, Granulamatosis, and certain types of leukemias and lymphomas. Rituxan binds specifically to the antigen CD20, a hydrophobic transmembrane protein that is located on pre-B and mature B lymphocytes. The antigen is expressed on 90% of B-cell non=Hodgkins lymphomas (NHL) but is not found on hematopoietic stem cells.

FDA approved uses:

1. Non-Hodgkin’s Lymphoma (NHL). Chronic Lymphocytic Leukemia (CLL).
2. 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 .
3. Granulomatosis with Polyangiitis (GPA) (Wegener’s Granulomatosis) and Microscopic Polyangiitis (MPA) in adult patients in combination with glucocorticoids

Available dosage forms: Injection: 100 mg/10 mL and 500 mg/50 mL solution in a single-use vial.

Usual dosage: Rituximab is administered by intravenous infusion. The dose for NHL is 375 mg/m2. The dose for CLL is 375 mg/m2 in the first cycle and 500 mg/m2 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/m2. The dose for RA in combination with methotrexate is two-1000 mg intravenous infusions separated by 2 weeks (one course) every 24 weeks or based on clinical evaluation, but not sooner than every 16 weeks. Methylprednisolone 100 mg intravenous or equivalent glucocorticoid is recommended 30 minutes prior to each infusion. The dose for GPA and MPA in combination with glucocorticoids is 375 mg/m2 once weekly for 4 weeks.

Contraindications: According to the manufacturer, there are no contraindications to Rituxan.
Special Warnings: Tumor lysis syndrome – administer aggressive intravenous hydration, anti-hyperuricemic agents, and monitor renal function. PML – monitor neurologic function. Discontinue RITUXAN. Hepatitis B reactivation with fulminant hepatitis, sometimes fatal – screen high risk patients and monitor HBV carriers during and several months after therapy. Discontinue RITUXAN if reactivation occurs. Infections – withhold RITUXAN and institute appropriate anti-infective therapy. Cardiac arrhythmias and angina can occur and can be life threatening. Monitor patients with these conditions closely. Bowel obstruction and perforation – evaluate complaints of abdominal pain. Do not administer live virus vaccines prior to or during RITUXAN. Monitor CBC at regular intervals for severe cytopenias.

Adverse reactions (side effects) of these medications: The most common side effects of Rituxan vary by the condition being treated and include Lymphoid Malignancies: Common adverse reactions in clinical trials of NHL were: infusion reactions, fever, lymphopenia, chills, infection and asthenia. Common adverse reactions in clinical trials of CLL were: infusion reactions and neutropenia. Rheumatoid Arthritis (RA): Common adverse reactions in clinical trials: upper respiratory tract infection, nasopharyngitis, urinary tract infection, and bronchitis. Other important adverse reactions include infusion reactions, serious infections, and cardiovascular events. Granulomatosis with Polyangiitis (GPA) (Wegener’s Granulomatosis) and Microscopic Polyangiitis (MPA): Common adverse reactions ( >15 %) in the clinical study were infections, nausea, diarrhea, headache, muscle spasms, anemia, peripheral edema (6.3). Other important adverse reactions include infusion reactions.

Common drug interactions: Abatacept and anakinra increase the likelihood of serious infections when used with rituximab. Live vaccines should not be given to patients taking rituximab. Close monitoring is required when initiating or discontinuing rituximab in patients taking cytochrome P450 substrates with a narrow therapeutic index (like warfarin, cyclosporine or theophylline).

Special instructions for patients: Notify doctor or get medical help right away if any of the following symptoms are experienced: hives or rash, itching, swelling of the lips, tongue, throat or face, sudden cough, shortness of breath, difficulty breathing, wheezing, weakness, dizziness, or palpitations. Progressive multifocal leukoencephalopathy has been reported. Contact physician if any of the following symptoms are experienced: confusion or problems thinking, loss of balance, change in the way you walk of talk, decreased strength or weakness on one side of the body, and blurred vision or loss of vision.

Full prescribing information may be found at the manufacturer‘s official website Rituxan.com or at the U.S. Food and Drug Administration’s website at Rituxan Info at Drugs@FDA

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