Various articles are used for the storage and/or administration of medicaments. Such articles include one or more surfaces that come into contact with the medicament, often for prolonged times. For example, drug-dispensing articles such as metered dose inhalers (“MDIs”) typically have a container for storing aerosol medicaments. Traditionally, these containers have been formed from metal (e.g., aluminum) and have a bare metal inner surface for contacting the medicament. These metal surfaces have typically suffered from several drawbacks which include, for example, adsorption of drug onto the metal surfaces (which can result in inconsistent or reduced drug delivery), reduced drug stability, and possible contamination of the drug (e.g., through extraction of residual organic compounds present on the metal surface). Despite these shortcomings, however, bare metal surfaces are still widely used for medicament containers such as MDI cans.
To address some of these shortcomings, polymer coatings such as fluoropolymers have been used as protective coatings for the inner surfaces of MDI cans to prevent interaction between medicament and an underlying metal substrate. These polymer coatings have tended to be solvent based. Although water-based fluoropolymer systems have been developed, these systems have typically required costly surface modifications prior to application.
What is needed in the marketplace is an improved polymer coating composition, and particularly an improved water-based coating composition for use in coating substrates exposed to medicaments.