Treatment with SB-705498 produced a significant improvement in cough reflex sensitivity to capsaicin at 2 hours and a borderline significant improvement at 24 hours compared with placebo ( adjusted mean difference of +1.3 doubling doses at 2 hours [ 95 % CI , +0.3 to +2.2 ; P = .0049 ] and +0.7 doubling doses at 24 hours [ 95 % CI , +0.0 to +1.5 ; P = .0259 ] ) .