A solid drug core insert can be manufactured by injecting a liquid mixture comprising a therapeutic agent and a matrix precursor into a sheath body. The injection can be conducted at subambient temperatures. The mixture is cured to form a solid drug-matrix core. The therapeutic agent can be a liquid at about room temperature that forms a dispersion of droplets in the matrix material. A surface of the solid drug core is exposed, for example by cutting the tube, and the exposed surface of the solid drug core releases therapeutic quantities of the therapeutic agent when implanted into the patient. In some embodiments, the insert body inhibits release of the therapeutic agent, for example with a material substantially impermeable to the therapeutic agent, such that the therapeutic quantities are released through the exposed surface, thereby avoiding release of the therapeutic agent to non-target tissues.