The present invention relates to frigostable compositions suitable for iontophoretic transdermal delivery of a triptan compound. The inventive compositions include a salt of a triptan compound, preferably sumatriptan succinate, a polyamine, a dicarboxylic acid, and water or an aqueous solvent mixture, with the composition being free of monocarboxylic acids. The invention further relates to the use of the composition as an integral component of an iontophoretic patch, preferably as an anodic reservoir of the patch.