the invention relates to biocompatible polycarbonate / polyamide polymer compositions for use in medical and surgical devices . additional additives , crosslinking agents , phosphites , and optionally a radiopaque filler or fillers can be used to produce the high performance compositions desired . the polymer compositions have improved melt processability along with balanced or enhanced physical and mechanical properties , especially when combined or over - extruded onto or covering other polymer layers , such as soft and / or flexible layers commonly used in medical device applications and catheter tips , for example . the ability to incorporate radiopaque compounds into these polymer compositions during melt processing offers improved methods for monitoring and visualizing medical devices when used inside the body and as well as improving the operating characteristics of the medical device components