A container, such as a metered dose inhaler, suitable for use with a propellant-based medicinal formulation, the container comprising one or more treated metal surfaces that come into contact with the medicinal formulation, wherein the one or more treated metal surfaces are characterized by an organic surface treatment compound covalently bonded to the metal surface through a reactive head group selected from either phosphonic acid or carboxylic acid and wherein the organic surface treatment compound is further characterized by an exposed, substantially non-reactive tail group disposed away from the metal surface. Also, metered dose inhaler canisters and valves with treated surfaces.