A patch is one form of transdermal formulations whose application for systemic therapy is recently in the limelight and has hitherto been applied to nitroglycerin, scopolamine, etc.
Among these patches, the patches known as the patch of nitroglycerin are one containing a crosslinked silicon polymer as a base, one containing a viscous silicone liquid as a base together with multi-pore membrane for controlled release of drug, and one containing a matrix composed of polyvinyl alcohol, polyvinyl pyrrolidone, and glycerol as a base. Also, the patch of scopolamine contains a mixture of high molecular polyisobutene, low molecular polyisobutene, and a mineral oil as a base.