Objectives: To investigate whether the efficacy and safety of Butterbur extract Ze339 are related to dosage when administered to patients with intermittent allergic rhinitis.
Design: Prospective, randomized, double-blind, placebo-controlled, parallel-group comparison.
Setting: Multicenter, including 6 outpatient general medicine and allergy clinics.
Patients: One hundred eighty-six patients were randomized (Butterbur Ze339 high dose, 60; low dose, 65; and placebo, 61 patients). Established diagnostic criteria for intermittent allergic rhinitis were confirmed by skin allergy tests in all patients.
Interventions: High-dose group, 1 tablet 3 times daily; low-dose group, 1 tablet twice daily; or matching placebo. All groups were treated for 2 consecutive weeks.
Main outcome measures: The main efficacy variable was change in symptoms from baseline to end point during the daytime. The secondary efficacy variables were Clinical Global Impression score, change in symptoms from baseline to treatment day 7, and responder rates. Statistical analysis was prospective, on an intention-to-treat basis.
Results: Improvement in the main efficacy variable was significantly superior in the Butterbur Ze339 groups, relative to placebo, and a significant dose relationship was observed between the 2 Butterbur doses. The clinicians' assessment of efficacy and the overall responder rates were significantly superior for the active groups compared with placebo. The incidence and type of adverse events were indistinguishable across the herbal treatment and placebo groups.
Conclusions: Butterbur Ze339 is an effective treatment for intermittent allergic rhinitis symptoms and is well tolerated. The effects of this herbal medicine are clear to patients and physicians in a double-blind evaluation against placebo.