Mean changes in pupil diameter over time after loperamide administration. Plots are separately drawn for all doses (A) or each dose of HM30181 (15, 60 and 180 mg in B, C and D, respectively). *P < 0.05 between loperamide plus quinidine vs. loperamide plus HM30181, +P < 0.05 between loperamide plus quinidine vs. loperamide alone and ∧P < 0.05 between loperamide plus HM30181 vs. loperamide alone. A) , loperamide alone; , quinidine + loperamide; , HM30181 + loperamide; B) , loperamide alone; , quinidine + loperamide; , HM30181 15 mg + loperamide; C) , loperamide alone; , quinidine + loperamide; , HM30181 60 mg + loperamide; D) , loperamide alone; , quinidine + loperamide; , HM30181 180 mg + loperamide