Stability of dopamine hydrochloride injection in the presence of dobutamine hydrochloride, tolazoline hydrochloride, and theophylline injections.

Dopamine hydrochloride is widely used to increase blood pressure, cardiac output, and peripheral perfusion in critically ill newborn infants and children with shock and congestive heart failure. These patients often require numerous other intravenous drugs such as dobutamine, tolazoline, and theophylline concurrently, but have limited venous access. As a result, two or more of these drugs may be administered through the same intravenous site. The objective of our study was to determine the physical compatibility and chemical stability of dopamine with dobutamine, tolazoline, and theophylline using simulated conditions encountered in the neonatal intensive care unit. Dopamine, dobutamine, tolazoline, and theophylline were studied at concentrations of 120 mg/100 mL, 120 mg/100 mL, 400 mg/100 mL, and 400 mg/500 mL, respectively, in 5% dextrose injection. The flow rate of dopamine was 0.3 mL/h while all combination drugs were run at 1 mL/h. Aliquots were collected at hourly intervals for 5 hours. A simultaneous static experiment was also performed by mixing dopamine with each combination drug in a ratio of 1:3 and allowing these to stand at room temperature. Samples were obtained at 0.5-hour intervals for 3 hours. Each aliquot was inspected visually for any change in color and clarity and analyzed in triplicate for dopamine content using high performance liquid chromatographic technique with electrochemical detection. Linear regression analysis was performed on the mean values of dopamine concentrations to assess its degradation. Dopamine was found to be physically and chemically stable with dobutamine, tolazoline, and theophylline. Thus, dopamine can be infused concurrently with any of these drugs in 5% dextrose injected at frequently used concentrations in newborn infants.