CXCL8 and chronic obstructive pulmonary disease: While roflumilast N-oxide inhibited IL-8 secretion in cells from smokers and smokers with COPD with similar maximal percent inhibition (56.6 ± 2.8% and 50.5 ± 1.5%, respectively) and potency (−logIC50 8.14 ± 0.21 and 8.28 ± 0.17 [M]), dexamethasone showed impaired maximal percent inhibition in both smokers and smokers with COPD (24.5 ± 7.9% and 21.6 ± 2.8%, respectively) and impaired potency in COPD patients (−logIC50 7.84 ± 1.7 [M]; Figure 4C and D, Table 2).