Catheter tubing comprises: an elongate body comprising a base thermoplastic polyurethane; and a compounded thermoplastic polyurethane co-extruded with the base thermoplastic polyurethane to provide a section of catheter tubing discrete from the elongate body, the compounded thermoplastic polyurethane comprising a thermoplastic polyurethane and a radiopaque material, wherein the catheter tubing comprises a first elastic modulus under first conditions prior to entry into a patient; and wherein when exposed to second conditions comprising two or more in vivo stimuli for a duration of time the catheter tubing comprises a second elastic modulus that is not more than fifty percent of the first modulus.