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Phosphodiesterase 4 inhibitors augment the ability of formoterol to enhance glucocorticoid - dependent gene transcription in human airway epithelial cells : a novel mechanism for the clinical efficacy of roflumilast in severe chronic obstructive pulmonary disease .
 Chemical: formoterol; Chemical: roflumilast
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: formoterol; Chemical: roflumilast