The invention relates to a composition for transdermal delivery, particularly iontophoretic transdermal delivery, of at least one cationic active agent or a salt thereof, said composition comprising said at least one cationic active agent or a salt thereof, at least one polyamine or/and polyamine salt, water or an aqueous solvent mixture, and optionally one or more additives. The invention further relates to the use of said composition as a component of a transdermal patch or of an iontophoretic transdermal patch, and to the use of said composition in a method for transdermally or iontophoretically administering cationic active agents, and to a method for determining the in vitro skin permeation properties of an active agent-containing iontophoretic composition.