Disclosed are lacrimal inserts and their method of use for delivery of medication to the eye. The plug includes a body portion sized to pass through a lacrimal punctum and be positioned within a lacrimal canaliculus of the eyelid. The plug may contain a core, or reservoir, at least partially within the body portion comprising a therapeutic agent that is configured to controlled release into the eye and is configured for release medication via a designated port, valve, or orifice in the insert housing and inhibits diffusion of medication via the housing itself.