Based on the population dose-response model of trough FEV1 data , the geometric mean potency ( ED50 ) of UMEC was 37 g ( 95 % confidence interval [ CI ] : 18 , 57 ) with a predicted maximum intrinsic efficacy ( Emax ) at trough of 0.185 L ( 95 % CI : 0.153 , 0.218 ) after QD dosing .