RESUMO
BACKGROUND: Butterbur (BB) or Petasites hybridus, a herbal remedy, exhibits in vitro inhibition of cysteinyl leukotriene biosynthesis. However, no placebo-controlled studies have been performed to evaluate the effectiveness of BB on objective outcomes such as nasal provocation testing in seasonal allergic rhinitis (SAR). METHODS: Twenty patients with grass-pollen-sensitized SAR were randomized in a double-blind, cross-over manner to receive for 2 weeks either BB 50 mg twice daily or placebo (PL) twice daily during the grass pollen season. Nasal adenosine monophosphate (AMP) challenge (the primary outcome) was administered as a single 400 mg/mL dose after each randomized treatment. RESULTS: Spontaneous recovery following AMP challenge (area under the response time profile curve as % x min+/-SEM) was significantly attenuated (P=0.028) with BB (584+/-289) compared to PL (1438+/-240); mean difference: 854 (95% CI 95-1614), and the maximum % peak nasal inspiratory flow reduction from baseline following AMP challenge was significantly blunted (P=0.036) with BB (30+/-4) compared to PL (43+/-5); mean difference: 13 (95% CI 1-25). CONCLUSIONS: BB exhibited protection against AMP-induced nasal responsiveness during the grass pollen season in sensitized patients. This is turn may explain its potential clinical efficacy in patients with SAR.