Provided are devices that are configured for gastric retention for a period of at least six hours (or at least three hours if the subject is in the fasted state) while maintaining their structural integrity and releasing or holding an active or diagnostic agent into or in gastric fluid of a human subject over that period, as well as methods of delivering an agent over an extended period by orally administering such devices to a subject, uses of an enteric polymer in the formation of devices that deliver an agent over an extended period of time, and methods of making such devices.
