Described is an article of manufacture useful for administration of pharmacologically-active substances, transdermally, orally or by means of subdermal implant comprising a solid vinyl plastisol layer for contacting a patient's tissue, internally or externally, the layer containing from about 20 up to about 70% by weight of a polyvinyl chloride resin or a polyvinyl chloride-polyvinyl acetate copolymer containing a minor proportion of vinyl acetate; from about 20-70% plasticizer composition; from abotu 0.5 up to 35% of pharmacologically-active substance such as isosorbide dinitrate, nicotine, clonidine, guanfacine, indomethacin, glyceryl trinitrate and prostaglandin and optionally excipients. Also described is the novel plasticizer-polyvinyl chloride composition of matter comprising 1-dodecylhexahydro-2H-azepin-2-one and polyvinyl chloride resin taken together with a pharmacologically-active substance whereint he 1-dodecylhexahydro-2H-azepin-2-one not only acts as a plasticizer but also acts as a penetration enhancer (through tissue) for the pharmacologically-active substance.