ACAAI: Rush Immunotherapy Provides Rapid Results Safely

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allergyPHILADELPHIA, Nov. 13 -- Rush immunotherapy can cram into a few days some six to 12 months worth of allergy shots, safely and with a low risk of serious systemic reactions or anaphylaxis, said researchers here.

In separate studies presented at the American College of Allergy, Asthma & Immunology meeting, investigators reported on the use of rapid allergen vaccination, also called rush immunotherapy, for safe, rapid desensitization of patients with allergic rhinitis, allergic asthma, and chronic rhinosinusitis.

 

The technique, although controversial because of its potential for inducing serious systemic reactions or anaphylaxis, can be safely used with proper selection of patients, premedication, and careful introduction of highly diluted antigens over a brief period, reported William Smits, M.D., in private practice in Fort Wayne, Ind.

He and his colleagues presented data on their cumulative experience with rush immunotherapy in more than 1,500 patients.

 

The goal of the therapy is to get patients in a single day not to maintenance therapy, but to a point where they're just a few weeks away from maintenance therapy, a goal that with conventional immunotherapy would take months to reach, said co-investigator Joseph T. Inglefield, III, M.D., in private practice in Hickory, N.C.

 

"While premedication with corticosteroids and antihistamines dramatically reduces the incidence of systemic reactions, safety continues to remain a primary concern for this procedure," Dr. Smits said.

 

In their study, the investigators used two separate half-day schedules with minor differences to rapidly desensitize 1,831 patients in outpatient settings -- typical large-scale allergy practices -- equipped to treat anaphylaxis.

 

The patients ranged in age from 1.7 to 77 years, All patients had positive subcutaneous skin tests to perennial and seasonal allergens.

 

Nearly all the patients had allergic rhinitis, 823 (53%) had asthma, and 738 (48%) were diagnosed with chronic rhinosinusitis.

 

About two-thirds of the patients were premedicated with prednisone 60 mg daily for adults, 2 mg/kg daily for children, and an antihistamine (H1 antagonist) -- either Zyrtec (cetirizine), Allegra (fexofenadine), or Claritin (loratidine) -- for three days.

 

"If you review the literature carefully, you find that if you premedicate for less than 72 hours, you'll get more systemic reactions," Dr. Smits said.

 

The remaining third of patients received a three day premedication regimen of prednisone and both H1 and H2 antagonists. The H2 antagonists were either Zantac (ranitidine), Pepcid (famotidine) or Tagamet (cimetidine).

 

The rapid sensitization protocol was performed over 2.5 hours on the treatment day, during which patients received eight injections 15 minutes apart, beginning with a 1:1,000,000 dilution and ending with a 1:1,000 dilution. Patients are observed for an additional half hour after administration of the last dose.

 

Patients then continued onto higher doses by resuming a conventional immunotherapy schedule until they reached their maintenance doses.

 

A total of thirty-four patients (2.1%) experienced a mild systemic reaction such as headache, dizziness, abdominal pain, chest pain, coughing, shortness of breath, and rhinitis.

 

Only one patient (<0.001%) had true anaphylaxis, and this patient was treated appropriately, was observed, and recovered without further problems, Dr. Smits said.

 

The investigators said that with additional experience they have been able to further reduce reaction rates, and that all patients with reactions responded to subcutaneous epinephrine and/or nebulized albuterol, and were sent home after an observation period.

 

"Our experience with rapid desensitization confirms that maintenance immunotherapy can be reached quickly, safely, and effectively under careful supervision. However, caution must be exercised when using this procedure as anaphylaxis does occur," Dr. Smits said.

 

He noted that systemic reactions occur less frequently when a lower targeted final dose is used.

 

In a separate small study, Sudhir Sekhsaria, M.D., of the Union Memorial Hospital in Baltimore, and colleagues, described adding the anti-IgE agent Xolair (omalizumab) to hasten the desensitization process and increase safety in high-risk patients.

 

The eight patients were chosen on the basis of a diagnosis of moderate to severe persistent allergic asthma, total serum IgE level, body weight and skin test positivity.

 

They were then treated with Xolair at standard doses, and then were started on multi-allergen immunotherapy with a modified rush protocol which shortened the standard 24 week protocol to six to eight weeks for patients to achieve maintenance immunotherapy concentrations.

 

The mean serum IgE was 302.5 IU/L (range 53-678 IU/L), and the mean FEV1 was 62.25% (range 43%-81%).

 

They found that all eight patients reached the maintenance immunotherapy dose with an average of eight doses (range six to nine), and all patients tolerated the regimen well, including one with a previous anaphylactic reaction to immunotherapy. In addition, there were no systemic reactions to the multi-allergen immunotherapy.

 

"This pilot study demonstrates that a modified rush multi allergen immunotherapy protocol, given in conjunction with omalizumab leads to a rapid attainment of maintenance immunotherapy with minimal risk to the subject," Dr. Sehksaria reported.

source - MedPageToday