The most important aspect of an indwelling inter vascular catheters is to maintain the patency of the catheter. We recently developed a Heparin Lock Flush Solution Kit for use with center vein catheters (only in use at our Hospital). The kit consists of a syringe filled with 9 mL of normal saline (NS) and 1 mL of heparin (1000 IU/mL). We performed the following tests to evaluate the stability, sterility, seal, and dust identification in the preparation. The stability and sterility data indicated that heparin maintained its potency and had no bacterial contamination for 3 months. Testing the seal of the syringe indicated that the seal remained patent at a temperature range of 5°C to 60°C. We also found that even if we sterilized a syringe made of polypropylene using ethylene oxide gas (EOG), no toxins (i.e., ethylene oxide, ethylene chlorohydrin, ethylene glycol) were produced. Next, we examined the preparation time and cost to evaluate the practical benefit of developing the kit. According to our results, the estimated preparation time and cost were 43% and 29% less than for previous methods, respectively. Finally, we put a label on the medicine kit to prevent any misuse by the medical staff.