Switching From Monthly Intravenous to Biweekly Subcutaneous Immunoglobulin: A Pharmacokinetic Modeling and Simulation Approach

Abstract

S U N D A Y 397 JTF-Recommended Allergen Dosing Used in Multi-Allergen Immunotherapy Induces Loss of Skin Test Reactivity Michael Vaughn, MD, PhD, Adrianne Vaughn, MD; Alamo Asthma & Allergy, San Antonio, TX, Alamo Allergy & Asthma, San Antonio, TX. RATIONALE: Immunotherapy can induce immunological changes that can result in long-term remission of symptoms after treatment discontinuation. The loss of skin test reactivity may be a marker for successful desensitization. We have evaluated the relationship between cumulative allergen doses and the loss of skin test reactivity with a retrospective review of our records. METHODS: Recordswere reviewed fromsequential immunotherapy started in 2008; selecting thosewho had undergone repeat skin testing between 12-24 month onmaintenance dosing.Mixing of skin prick positive allergens targeted the Joint Task Force immunotherapy practice parameter –recommended ‘‘optimal’’ dosing ranges for most major allergens. Recommended maintenance dosing frequency was 0.5cc bimonthly, but varied. RESULTS: 77 patients received subcutaneous immunotherapy containing, on average, 19 allergens per patient Therewas no significant difference in allergen number between groups (p50.73). Serial skin testing changes were compared between those who had received monthly immunotherapy > 0.49cc (group 1) and 0.1-0.49cc (group 2). Groups 1 & 2 received maintenance immunotherapy for a similar average of 16.8 and 16.7months respectively (p50.76). There was a significant 15.7% difference in mean loss of skin test reactivity between groups (p50.015). A greater than 50% loss of reactivity was seen in 59% of group 1 and 17.6% of group 2. The average administered volumes for groups 1 & 2 were 0.84cc/mo. and 0.35cc/mo. respectively. CONCLUSIONS: Multi-allergen immunotherapy, targeting JTF-recommended ‘‘optimal’’ dosing recommendations, commonly results in the loss of skin test reactivity. Cumulative allergen doses of only 2-3 fold lower than recommended often failed to induce skin test sensitivity loss.