Rituxan, also known as Mabthera or Rituximab, is a drug used to treat lymphoma and other diseases. Allergic reactions are a a fairly common side effect of this drug.
Rituxan is a monoclonal antibody drug, meaning it targets a specific molecule on cells affected by lymphoma and a few other immune diseases, such as rheumatoid arthritis (RA). It is an effective treatment in non-Hodgkin’s lymphomas and has been shown to improve survival in some of the common types of NHL including diffuse large B-cell lymphoma and follicular lymphoma.
Why Are Allergic Reactions Common with Rituxan?
Rituxan contains a small amount of protein from mouse tissue. For this reason, Rituxan is known as a "chimeric antibody," which means it's made of tissues from two different species. While this is crucial for the drug to work, our bodies are geared to recognize all foreign tissue and start an immune reaction against it. The allergic reaction from Rituxan is due to mouse proteins in the drug.
Signs of Rituxan Allergy
The common signs of Rituxan allergy are:
- fever and chills – these are the most common reactions and occur in most individuals
- throat irritation or watering from the nose
- swelling of hands, feet or face
- fall in blood pressure and dizziness
- spasm of the throat, similar to asthma
These allergic reactions usually occur within 30 minutes to 2 hours of starting the drug infusion and are most likely to occur with the very first infusion (nearly 80 percent of patients have a reaction) and become less frequent with successive cycles.
Rarely, severe reactions may occur, including:
- severe breathing problems
- heart attacks
- a serious fall in blood pressure and shock.
How Are Allergic Reactions Treated?
The first thing that the nurse or doctor does is slow down or stop the infusion. For some mild reactions, that is all that may be required. A number of drugs can be administered to reduce or stop the reaction. These include acetaminophen, antiallergics, IV saline or drugs to increase blood pressure, and steroids. In nearly all patients, the reaction can be controlled quickly with these measures. For severe reactions, intensive care units may be more appropriate – with measures to maintain and monitor the blood pressure and breathing. Though deaths have been reported from infusion reactions, they are extremely rare.
Can Infusion Reactions Be Prevented?
A few measures can prevent or reduce allergic reactions with Rituxan:
- Premedication -- taking antiallergic medicines and steroids before starting the infusion.
- Starting the infusion slowly. This is very important for the first infusion when reactions are the most common. As a routine, infusions are started slowly and the rate is increased when no reactions occur.
- Stopping blood pressure medication before infusions – since a fall in blood pressure can occur during a reaction, doctors sometimes advise patients to stop using their blood pressure medications before the infusion. Only do this under specific doctor's orders.
Those who have had a mild or moderate reaction with Rituxan may be given the drug slowly and need to take all precautions for subsequent treatments. Those who have severe reactions are usually not administered the drug any more.