Safety Considerations in Assessing the Role of Immunotherapy in Allergic Disorders

Abstract

Specific immunotherapy (SIT) is accepted as an effective treatment of allergic diseases when high quality extracts are used. However, this form of treatment can cause untoward reactions among which systemic reactions are the most severe. Although life-threatening reactions are rare and deaths exceptionally reported, SIT should be prescribed by allergists to patients with well defined characteristics, and administered with care by (or under the close supervision of) physicians trained to deal rapidly with the reactions. Reactions with standardised extracts occur mostly during the dose increase phase but they can be prevented using adapted schedules and premedication. During maintenance injections or when vial batches are changed, standardised extracts of known shelf-life usually result in a low rate of systemic reactions. Patients with asthma are more prone to develop systemic reactions, and allergens should not be administered to patients with a forced expiratory volume in 1 second (FEV1) under 70% of predicted or in those who have unstable or symptomatic asthma. Systemic reactions may be observed with all allergens and allergenic preparations although it appears that high molecular weight extracts may be safer.

Allergic Rhinitis and its Impact on Asthma (ARIA) 2008*

“…When treating rhinitis patients, the risk of serious anaphylactic reactions is rather limited compared to when treating asthma patients (1178,1193,1649,1678). In many of the recently published studies, systemic side effects were still noticed using standardized extracts (1104), allergoids (1653) or recombinant allergens (1671).…”

“…The indications for immunotherapy in asthma are hampered by safety issues (1678). Most guidelines propose not to use immunotherapy in patients with severe or uncontrolled asthma because of the risk of severe bronchial reactions using subcutaneous immunotherapy (2047-2049).…”

Safety of an Ultra-Rush Immunotherapy Build-Up Schedule with Therapeutic Vaccines Containing Depigmented and Polymerized Allergen Extracts

“…In an attempt to overcome these disadvantages, glutaraldehyde-modified allergen extracts were developed, proving to be safer than unmodified vaccines while retaining clinical efficacy [16, 17]. The introduction of a depigmentation step, before the polymerization process removes the adsorbed pigments, enhances the solubility of the allergoids and inactivates the enzymatic activity [18].…”

Safety of Subcutaneous Specific Immunotherapy with Pollen Allergen Extracts for Respiratory Allergy

“…It is an effective treatment of allergic diseases when high-quality extracts are used [1]. The therapeutic efficacy of SIT in allergic rhinitis and asthma has been confirmed in open-label and double-blind trials, as well as in meta-analysis [2, 3, 4].…”