The safety and activity of polymerized ragweed: A double-blind, placebo-controlled trial in 81 patients with ragweed rhinitis

Eighty-one patients with ragweed pollinosis were recruited for a double-blind, histamine placebo-controlled study of the safety, immunogenicity, and efficacy of 15 weekly injections of polymerized ragweed (PRW) immunotherapy totaling 1359 allergy units. Patients were paired on the basis of cutaneous end point titration to RAST standardized extracts of giant and short ragweed. One patient of each pair was randomized to receive PRW, and the other patient, a caramelized glucose histamine placebo. Symptom and medication score diaries were completed by 68 patients. All 68 patients received the full maintenance dose. No patient dropped out because of adverse reactions, and there were no systemic reactions. Except for one patient receiving placebo who developed mildly elevated liver function tests, there were no clinically significant changes in routine laboratory tests associated with injections. By Student's t test on log-transformed values, blocking antibody rose significantly in the patients receiving PRW but was unchanged in those receiving placebo. By Wilcoxon paired signed-rank test, the symptom and medication scores in the patients receiving PRW were significantly lower than scores in the patients receiving placebo. This study demonstrates the safety, immunogenicity, and activity of PRW in the treatment of ragweed pollinosis.