Effect of ketotifen premedication on adverse reactions during peanut oral immunotherapy

BACKGROUND: Oral immunotherapy (OIT) has shown promise in inducing desensitization for food allergy. However, there are safety concerns regarding the frequency and severity of adverse events during food OIT. OBJECTIVE: To evaluate the effect of Ketotifen premedication on adverse reactions during peanut OIT. METHODS: A randomized single blind placebo controlled pilot study was performed. Peanut OIT was performed using a previously published protocol. Ketotifen was up-titrated to 2 mg twice daily over two weeks (week -2 to 0), followed by a peanut OIT initial escalation day (day 1). Ketotifen was administered from week 0–4 of peanut OIT; reactions to peanut OIT doses were recorded by clinic staff and subject diary. RESULTS: Six subjects (median age 10 years, peanut IgE >100kU(A)/L) were enrolled, 4 randomized to Ketotifen, 2 to placebo. The most common side effect of Ketotifen was fatigue (9% during up-titration). The rate of reaction per peanut OIT dose was lower for subjects on ketotifen (K) compared to placebo (P) during initial escalation on day 1 (K: 22% (8/36) vs. P: 67% (12/18)); week 0–4 build-up doses (K: 75% (3/4) vs. P: 100% (2/2)); and week 0–4 home doses (K: 50% (54/108) vs. P: 82% (27/33)). The rate of gastrointestinal symptoms per peanut OIT dose was also lower for subjects on ketotifen during initial escalation on day 1 (K: 17% (6/36) vs. P: 61% (11/18)); week 0–4 build-up doses (K: 75% (3/4) vs P: 100% (2/2)); and week 0–4 home doses (K: 46% (50/108) vs. P: 82% (27/33)). CONCLUSIONS: Ketotifen premedication is well tolerated and reduces the rate of gastrointestinal symptoms during peanut OIT. These findings require confirmation in a larger study of Ketotifen premedication used throughout peanut OIT. TRIAL REGISTRATION: Clinical Trials number: NCT0162515