Rituximab

Description

Rituximab is a genetically engineered, fused mouse/human anti-CD40 monoclonal antibody that targets B lymphocytes by binding specifically to CD20 antigen, a protein found on the surface of B cells at certain stages in their life cycle. Rituximab is composed of two heavy chains of 451 amino acids and two light chains of 213 amino acids with an approximate molecular weight of 145 kDa. Its binding affinity for the CD20 antigen is approximately 8.0 nM.

Uses

Antineoplastic (microtubule inhibitor); monoclonal antibody.

Uses

Rituximab is being used for Coronavirus-related infections.

brand name

Rituxan (IDEC).

General Description

Rituximab (Rituxan, Chimeric) is an MAb directed againstthe CD20 antigen expressed on the surfaces of normal andmalignant B lymphocytes. The MAb is produced in mammalian(CHO) suspension culture and is a chimeric(murine/human) MAb of the IgG1 κ type. The protein is composed of murine light and heavy chain variable regionsand human constant regions. Rituximab is indicated for thetreatment of patients with relapsed or refractory, low-gradeor follicular, CD20(+) B-cell non-Hodgkin lymphoma.Rituximab binds specifically to antigen CD20 (human Blymphocyte–restricted differentiation antigen, a hydrophobictransmembrane protein expressed on pre-B and matureB lymphocytes). CD20 is a protein of 35 to 37 kDa, and itmay play a role in B cell activation and regulation and maybe a calcium ion channel. The antigen is also expressed onmore than 90% of non-Hodgkin lymphoma B cells but is notfound on hematopoietic stem cells, pro-B cells, normalplasma cells, or other normal tissues. CD20 regulates theearly steps in the activation process for cell cycle initiationand differentiation.

Clinical Use

Rituximab is a sterile, clear, colorless, preservative-free, liquid concentrate formulated for IV administration. It has changed the treatment of rheumatoid arthritis by showing that targeted B-cell therapy in combination with methotrexate can reduce signs and symptoms of rheumatoid arthritis in adult patients with moderately to severely active rheumatoid arthritis who have had an inadequate response to one or more TNF antagonist therapies. Although B cells once were considered to be one of the main contributing factors in the pathogenesis of rheumatoid arthritis, recent evidence has shown that Tcells, dendritic cells, and macrophages also were involved. Rituximab has rekindled interest in B cells, highlighting their important role in perpetuating the inflammatory process and showing how they may interact with other cell types and contribute to joint inflammation.

Side effects

Side effects include flu-like signs and symptoms such as fever, chills, and nausea. Some people experience an “infusion-reaction complex,” such as difficulty breathing and heart problems, that has resulted in fatalities.

Drug interactions

Potentially hazardous interactions with other drugs
Vaccines: risk of generalised infections with live vaccines - avoid.

Metabolism

The mechanisms involved in the metabolism and elimination of rituximab are not fully understood, it is postulated that rituximab is most likely removed by opsonization via the reticuloendothelial system when bound to B lymphocytes, or by human antimurine antibody production. It is then degraded nonspecifically in the liver and excreted in the urine.