Mannitol BPT

Dry powder mannitol (Aridol; Pharmaxis, French's Forest, NSW, Australia) was administered according to the manufacturer's recommendations, and FEV₁ values were recorded as prescribed by current guidelines.15 The FEV₁ recorded after inhalation of a placebo capsule served as the baseline value. The challenge was completed when a ≥15% drop in FEV₁ from baseline occurred, which was considered a positive response, or when the maximum cumulative dose of mannitol (635 mg) was administered. Asthmatics exhibiting a decrease in FEV₁ of at least 15% from baseline after inhalation of ≤635 mg mannitol were enrolled in the positive-mannitol BPT group, and the others were placed in the negative-mannitol BPT group. For positive challenge results, the cumulative provocative dose causing a 15% drop in FEV₁ (PD₁₅ dose) was calculated by log-linear interpolation of the final two data points. The responses to mannitol were expressed as PD₁₅ values.