An implant configured for disposition within or adjacent to a body cavity, tissue, duct, or fluid, the implant comprising: a drug core comprising: (a) a matrix (254, 362, 454) including a polymer; (b) a therapeutic agent (252, 360, 452) contained within the matrix, and (c) an excipient dissolved or dispersed within the matrix, the excipient configured to any of, modify a release rate of the therapeutic agent into the body cavity, tissue, duct, or fluid relative to a comparable release rate in the absence of an excipient; increase a loading of the therapeutic agent substantially uniformly dissolved or dispersed within the matrix, relative to a comparable loading of the therapeutic agent that is substantially uniformly dissolved or dispersed, in the absence of an excipient; increase retention of the agent at or adjacent to a site of release in a living body or increase penetration of adjacent body tissue by the agent, or both, relative to the retention or penetration or both from a comparable implant in the absence of the excipient; or any combination thereof, wherein an amount of the therapeutic agent in a volumetric portion of the matrix is similar to an amount of the therapeutic agent in any other equal volumetric portion of the matrix; characterized in that the polymer of the matrix is a non-biodegradable polymer; and wherein the implant is an ocular implant, adapted for disposition through a punctum and into a canaliculus of a human eye for release of the therapeutic agent therefrom. a drug core comprising: (a) a matrix (254, 362, 454) including a polymer; (b) a therapeutic agent (252, 360, 452) contained within the matrix, and (c) an excipient dissolved or dispersed within the matrix, the excipient configured to any of, modify a release rate of the therapeutic agent into the body cavity, tissue, duct, or fluid relative to a comparable release rate in the absence of an excipient; increase a loading of the therapeutic agent substantially uniformly dissolved or dispersed within the matrix, relative to a comparable loading of the therapeutic agent that is substantially uniformly dissolved or dispersed, in the absence of an excipient; increase retention of the agent at or adjacent to a site of release in a living body or increase penetration of adjacent body tissue by the agent, or both, relative to the retention or penetration or both from a comparable implant in the absence of the excipient; or any combination thereof, (a) a matrix (254, 362, 454) including a polymer; (b) a therapeutic agent (252, 360, 452) contained within the matrix, and (c) an excipient dissolved or dispersed within the matrix, the excipient configured to any of, modify a release rate of the therapeutic agent into the body cavity, tissue, duct, or fluid relative to a comparable release rate in the absence of an excipient; increase a loading of the therapeutic agent substantially uniformly dissolved or dispersed within the matrix, relative to a comparable loading of the therapeutic agent that is substantially uniformly dissolved or dispersed, in the absence of an excipient; increase retention of the agent at or adjacent to a site of release in a living body or increase penetration of adjacent body tissue by the agent, or both, relative to the retention or penetration or both from a comparable implant in the absence of the excipient; or any combination thereof, modify a release rate of the therapeutic agent into the body cavity, tissue, duct, or fluid relative to a comparable release rate in the absence of an excipient; increase a loading of the therapeutic agent substantially uniformly dissolved or dispersed within the matrix, relative to a comparable loading of the therapeutic agent that is substantially uniformly dissolved or dispersed, in the absence of an excipient; increase retention of the agent at or adjacent to a site of release in a living body or increase penetration of adjacent body tissue by the agent, or both, relative to the retention or penetration or both from a comparable implant in the absence of the excipient; wherein an amount of the therapeutic agent in a volumetric portion of the matrix is similar to an amount of the therapeutic agent in any other equal volumetric portion of the matrix; characterized in that the polymer of the matrix is a non-biodegradable polymer; and wherein the implant is an ocular implant, adapted for disposition through a punctum and into a canaliculus of a human eye for release of the therapeutic agent therefrom.