This invention provides potassium channel modulators which are compounds of formula I where at least one of W and Z is N； where the moiety is one of Groups A or B below A where Ar is a 1,2-fused, six membered ring aromatic group, bearing substituents R1 and R2 as defined below, and containing zero or one ring nitrogen atom； and where other substituents are defined herein. The invention also provides a composition comprising a pharmaceutically acceptable carrier and at least one of the following: i) a pharmaceutically effective amount of a compound of formula I and ii) a pharmaceutically acceptable salt, ester, or prodrug thereof. The invention also provides a method of preventing or treating a disease or disorder which is affected by activities of potassium channels, comprising administering to a patient in need thereof a therapeutically effective amount of a compound of formula I or a salt, ester, or prodrug thereof.
