What is Which of the following statement about rituximab is FALSE: and explain in detail?
Ans. (B) It has dose-dependent kinetics(Ref Goodman Gilman 12th/1746-1747, KDT 8th/e p931-932)Rituximab is a chimeric monoclonal antibody against CD-20 B-cell antigen. It acts by depleting B-cells.Rituximab follows first order kinetics. Its clearance remains constant irrespective of plasma concentration. Dose-dependent kinetics means zero-order kinetics i.e. clearance and t1/2 change with dose (plasma concentration). Drugs following zero-order kinetics are warfarin, alcohol, high dose aspirin, tolbutamide, theophylline and phenytoin.Infusion-related reactions are seen in approximately 50% of patients receiving first infusion. The incidence decreases with subsequent infusions. Starting with low doses and pre-treatment with steroids or antihistaminics are the methods to reduce infusion-related reactions.Rituximab may cause reactivation of hepatitis B. Patients should be screened for hepatitis B before initiation of therapy. It rarely causes reactivation of JC virus leading to progressive multifocal leukoencephalopathy.Rituximab can be used for treatment ofNon Hodgkin lymphomaMantle cell lymphomaChronic lymphocytic leukemiaAuto-immune hemolytic anemiaDiffuse large B cell lymphomaThrombotic thrombocytopenic purpura (TTP)Gastric lymphomaRheumatoid arthritisImmune thrombocytopenic purpura (ITP)Pemphigus vulgarisSjogren syndromeSLE