How rituximab works
Rituximab is a therapeutic antibody (therapeutic immunoglobulin). Antibodies are proteins (proteins) that are naturally produced in the body and are designed to recognize foreign or harmful proteins (for example, from parasites, bacteria and viruses) and render them harmless.
Antibodies are produced by B cells (also called B lymphocytes). These are a type of cell from the group of white blood cells. On contact with a foreign substance, they form suitable antibodies against it, which attack the intruder.
Like many other cells, B cells have surface proteins by which they can be identified: The protein CD20. This fact is used in the treatment of diseases associated with an excessive number of B cells in the body, with overactive B cells or functionless B cells.
Also known as “targeted cancer therapy,” the treatment has far fewer serious side effects than conventional therapies that use agents that indiscriminately affect all dividing cells (cancer cells and healthy cells).
Absorption, degradation and excretion
After infusion or injection into blood vessels (intravenously) or under the skin (subcutaneously), rituximab antibodies spread through the circulation and reach the site where they are intended to act.
When is rituximab used?
Rituximab is used to treat the following diseases:
- Non-Hodgkin’s lymphoma (NHL, cancer of the lymphatic system) – used in combination with other agents
- Chronic lymphocytic leukemia (CLL) – used in combination with other agents
- Rheumatoid arthritis – use in combination with the active substance methotrexate
- Granulomatosis (tissue nodules) with polyangiitis (inflammation of vessels)
Rituximab is used in several cycles with an interval of weeks to months. Off-label use of rituximab is also used, for example, in multiple sclerosis or acute kidney inflammation (glomerulonephritis).
How rituximab is used
Thus, active ingredient quantities of about 500 to 1000 milligrams of rituximab are administered per treatment. The number of cycles and the interval between them are also determined by the physician. Some patients receive the active substance weekly, others at intervals of up to three months.
What are the side effects of rituximab?
During treatment with rituximab, more than ten percent of patients experience side effects such as bacterial and viral infections, decreased white blood cell and platelet counts, allergic reactions, sometimes with swelling (edema), nausea, itching, rash, hair loss, fever, headache and chills.
Earache, cardiac arrhythmias, high or low blood pressure, respiratory disorders, shortness of breath, cough, vomiting, abdominal pain, digestive disorders, skin disorders, muscle pain, and cold symptoms are also observed. Such side effects occur in one in ten to one hundred people treated.
What should be considered when using rituximab?
Contraindications
Rituximab must not be used in:
- active, severe infections
- patients with a severely weakened immune system
- severe cardiac insufficiency (heart failure)
Drug interactions
There are no known interactions between rituximab and other agents.
Patients with severe infections (such as tuberculosis, HIV, viral hepatitis) should not be treated with rituximab as this further weakens the immune system.
Age restriction
For certain indications, infusions with the active substance are approved from the age of six months. The dosage is determined individually.
Pregnancy and breastfeeding
Rituximab is usually discontinued early in the event of a planned pregnancy or in the event of an unexpected pregnancy as soon as it becomes known. Data from the manufacturer’s databases failed to detect clinically relevant symptoms in the newborns in the majority of cases.
Due to the large molecular mass, rituximab is unlikely to pass into breast milk. In any case, the decision for treatment during breastfeeding is made by specialists.
How to receive medication with rituximab
Treatment with rituximab is usually given directly in a hospital or specialized clinic, which then prepares the drug on a patient-by-patient basis.
Since when is Rituximab known?
A marketing authorization extension was granted in the EU in 2006 for the treatment of rheumatoid arthritis and in 2012 for Wegener’s disease. The US patent expired in 2015. In the meantime, the first biosimilars with rituximab are on the market.
