Injection Reactions Site Clinical Trial
Official title:
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.
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