A dosage form for delivery of a therapeutic agent to a subject is described. The dosage form contains: (a) an outer wall defining an interior compartment; (b) within the interior compartment, a therapeutic agent; (c) at least one exit orifice formed by laser ablation of the outer wall for release of the agent therethrough, and (d) a barrier layer disposed between the outer wall and the interior compartment in at least a region corresponding to the exit orifice. The barrier layer comprises a material that allows the barrier layer to remain intact during laser-formation of the at least one exit orifice in the outer wall. Also disclosed is a method for controlling the depth of laser ablation of a dosage form during laser formation of an exit orifice in an outer wall of the dosage form.