Administrating incompatible drugs by a retrograde intravenous infusion system

Use of a retrograde infusion system for concurrent intravenous administration of two incompatible drugs separated by a barrier fluid was studied. Four different barrier fluids (5% dextrose injection, 10% dextrose injection, 0.9% sodium chloride injection, and sterile water for injection) were used to separate sodium bicarbonate and calcium chloride. The primary infusion was 5% dextrose injection. The delivery system was visually inspected for formation of precipitate (calcium carbonate) upon addition of the two drug solutions and 2 ml of the barrier fluid. If precipitation occurred, the procedure was repeated, increasing the volume of barrier fluid incrementally until no precipitate could be seen. If no precipitate was seen with the initial 2 ml of barrier fluid, the volume of barrier fluid was decreased until precipitation occurred. These procedures were repeated for each barrier fluid at flow rates of 5-20 ml/hr for 90 minutes. The minimum volume of barrier fluid needed to prevent precipitate formation was determined in triplicate at each flow rate. The minimum volume of barrier fluid that prevented precipitate formation was approximately 2.0 ml. This volume did not differ significantly by barrier solution type or by flow rate. Sodium bicarbonate and calcium chloride can be administered concurrently by the retrograde intravenous method without visual incompatibility when separated by greater than or equal to 2 ml of barrier fluid, and this method can probably be used for administration of other potentially incompatible drugs.