Rapid Desensitization, also known as rush immunology, is a type of immunotherapy that greatly accelerates the process of building up a patient's tolerance to allergens. Normally, immunotherapy, whether administered by injection or sublinguinally, takes a period of several years (typically 5) to be fully effective, with patients receiving weekly shots for several months until a maintenance dose is reached. With rapid desensitization, however, the process is compressed to the degree that several months of tolerance build-up may be achieved in a single day of injections. In some patients, a response can be observed almost immediately.
Most rapid desensitization involves inhaled allergens or medications, such as antibiotics, steroids, of chemotherapy drugs, that the patient requires as treatment for other medical conditions. While rapid desensitization has been used for food allergies and insect stings as well, it may require a longer time frame to be effective in these cases.
Benefits of Rapid Desensitization
During immunotherapy, the body becomes desensitized, or accustomed, to substances to which it once had allergic reactions. The body also finds a way to produce protective antibodies against the targeted allergen. The latter method is similar to the way a vaccination works. There are strong benefits to rapid desensitization.
In addition to providing much more rapid results, rush immunology has been found, through research presented at the 52nd annual meeting of the American College of Allergy, Asthma, and Immunology, to be not only effective, but very safe. Only 2 percent of the patients studied experienced mild systemic reactions, such as nausea, headache or dizziness as a result of treatment, and only one patient out of more than 1800 experienced anaphylaxsis. Even in patients with cystic fibrosis, a population known to be difficult to treat for antibiotic allergies, a government study has shown the rapid process was effective and that more than 95 percent of patients experienced no adverse side effects.
Because the need for immunotherapy arises when medications fail to control symptoms and often when avoiding the allergen is difficult or impossible, the speedier relief is experienced, the better. Patients who suffer moderate to severe symptoms because their allergens are unavoidable, such as dust in the workplace or pet dander in the home, are anxious to resolve the situation as quickly as possible.
The Rapid Desensitization Procedure
Most rapid desensitization procedures take place within one day. Patients, however, must be premedicated before the desensitization process begins. Typically, patients are premedicated with ranitidine, a histamine H2-receptor antagonist, and prednisone, a corticosteroid, for 3 days prior to treatment. These medications will lessen the patient's allergic reactions.
During the procedure, patients are administered small doses of the allergens at fixed time intervals in an attempt to accustom their bodies to the offending substances. In one study, for example, patients received eight injections over a 6-hour period, followed by 2 hours of medical observation. The majority of the patients were able to tolerate the equivalent of a maintenance dose in only one day. This is astonishingly rapid, considering that, if more conventional immunology had been administered, the patients would have taken many months to reach the same goal. For patients who are extremely uncomfortable, or who require immediate administration of antibiotics, aspirin, or chemotherapy drugs, this speed of effective immunology is of utmost importance.
Risks of Rapid Desensitization
Although rapid desensitization is considered a high-risk procedure because of the chance of anaphylaxsis, the frequency of systemic reactions during rapid desensitization is startlingly similar to the rate of reactions during conventional immunotherapy. For patient protection, rush immunology always takes place in a clinical setting where any necessary medications and equipment are available in case of a patient's severe allergic reaction.
Increased risk of some form of systemic reaction has been found in patients who do not receive their next injection within 7 days of treatment, so it is extremely important that patients follow the medical protocol. Lack of compliance with recommended treatment can be dangerous.
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