A sulfonamide resulting from the formal condensation of p-methoxybenzenesulfonic acid with the anilino nitrogen of 2-(aminomethyl)-N-(2-hydroxyethyl)aniline in which the hydrogens of the primary amino group have been replaced by methyl and p-chlorocinnamyl groups. KN-93 is a selective inhibitor of Ca(2+)/calmodulin-dependent protein kinase II.