Can Epinephrine Coated Syringe for Subcutaneous Immunotherapy (SCIT) Reduce Large Local Reaction?
Can Epinephrine Coated Syringe for Subcutaneous Immunotherapy (SCIT) Reduce Large Local Reaction?
Allergen immunotherapy is effective in the management of allergic asthma, allergic
 rhinitis/conjunctivitis, and stinging insect hypersensitivity. The most common side effect of
 subcutaneous allergen specific immunotherapy (SCIT) is local reactions (LR). Although some
 studies indicated that LR did not predict systemic reaction (SR), patients with higher
 frequency of large local reaction (LLR) were reported to have higher risk for SR. Epinephrine
 may decrease LLR due to its vasoconstrictive effect . The objective of this study was to
 compare the size of LLR in patients receiving SCIT with epinephrine or normal saline coated
 syringe. The patients who complained of frequent LLR despite pre-medication and local
 treatment were recruited.
Allergen immunotherapy (AIT) is an immune mediated treatment which modifies T helper (Th)
 2-directed response through the interplay between regulatory T and B cells, blocking IgG4
 antibodies and tissue effector-mediated mechanisms. Aeroallergen immunotherapy is recommended
 for patients with allergic rhinitis, allergic conjunctivitis or allergic asthma whose
 symptoms were not adequately controlled by antigen avoidance and pharmacotherapy. AIT could
 reduce symptoms and medication usage in respiratory allergy. In children, AIT prevented the
 progression from allergic rhinitis to asthma and prevented new onset of allergen
 sensitization in monosensitized patients. The administration of allergen by subcutaneous
 injection (SCIT) is a common practice among allergists.

 The benefits of SCIT must be weighed against the risks of side effects which can be mild or
 life threatening. Adverse allergic reactions to SCIT were classified as either local (LR) or
 systemic reactions (SR).6 Large local reactions (LLR) are defined as erythema and/or swelling
 (> 25 mm) at the site of injection. The timing of adverse reactions were categorized into
 immediate (occurring within 30 min) and late reactions (occurring > 30 min after injection).
 LR associated with SCIT ranged from 26-72% of patients and 0.7-4% of injections. SR were
 reported to occurred in 3.7% of patients and 0.3% of injection. Recent prospective study in
 pediatric patients who received SCIT showed immediate LR in 54.6%, delayed LR in 56.1%,
 immediate SR in 2.2% and delayed SR in 7.4% of the patients. Severe SR were seen in 0.03% of
 all treatments which appeared within 30 minutes after the injections. The author concluded
 that children had similar rates of LR compared to adult patients but had lower rates of
 severe SR.

 Several studies indicated that individual LR did not predict subsequent SR. The rate of SR
 were not change despite the dose adjustment after a LR. However, patients with greater
 frequency of LLR might be at an increased risk for future SR. Recognizing the significance of
 frequent LLRs is important for designing safer protocols for successful SCIT.

 In the Division of Allergy and Clinical Immunology, Department of Pediatrics, Faculty of
 Medicine Siriraj Hospital, Mahidol University, we performed SCIT in approximately 100
 patients and 2000 injections per year. The LR associated SCIT were complained in 75% of the
 patients. Of the patients who experienced LR, 80% had LR more than 25 mm which was considered
 LLR.

 Many strategies to prevent or minimize LR were reported. Oral antihistamines, leukotriene
 receptor antagonist (LTRA) or anti-IgE could reduce LR during the built-up phase. Cold
 compression or topical steroid were used to reduce the LR without any strong evidence. To our
 knowledge, the benefit of epinephrine coated syringe prior to drawing the allergen extract
 for SCIT in patients with frequent LLR has never been explored in any controlled trial.

 The objective of this study is to compare the size of LR in patients with frequent LLR who
 receive SCIT by coating syringe with epinephrine or placebo prior to drawing allergen
 extract.
Inclusion Criteria:

 -  Patients older than 6 years old who received SCIT at Pediatrics allergy departments at
 Siriraj hospital

 -  Patients who develops larges local reactions(mean wheal diameter > 25 mm.) during
 SCIT.

 -  Patients who received SCIT in maintenance phase.

 Exclusion Criteria:

 -  Patients who develops systemic reactions (more than grade 1) during SCIT.