This disclosure relates to methods of treating or preventing cystic fibrosis transmembrane conductance regulator (CFTR) mediated diseases such as cystic fibrosis, chronic obstructive pulmonary disease, chronic pancreatitis, chronic bronchitis, asthma, mucus formation, comprising administering an effective amount of a 3-(phenyl)-N-(4-phenoxybenzyl)-1,2,4-oxa-diazole-5-carboxamide compound, salt, or derivative thereof to a subject in need thereof. In certain embodiments, the 2-amino-N-benzylidene-acetohydrazide compound is 3-(3,5-dibromo-4-hydroxyphenyl)-N-(4-phenoxybenzyl)-1,2,4-oxadiazole-5-carboxamide.