Apparatus is provided, including one or more drug patches (20) and a surface (22) configured to hold the one or more drug patches. A housing (24) is shaped to define one or more gas inflow openings (30) that are configured to facilitate drying of the patches by directing a flow of a gas toward the patches, a midline of the flow being at an angle of less than 20 degrees from a normal to the surface. Other embodiments are also described.