Y-Site Compatibility of Doxapram Hydrochloride with Commonly Used Drugs in the NICU

In neonatal intensive care units (NICUs), limited vascular access often necessitates the co-administration of multiple intravenous medications through a single line, increasing the risk of physicochemical incompatibility. Doxapram hydrochloride (DOP), a respiratory stimulant used when caffeine therapy is insufficient, is continuously infused and frequently requires Y-site administration with other drugs. This study systematically evaluated the compatibility of seven commonly used NICU medications—midazolam (MDZ), dalteparin sodium (DLT), cefazolin, cefepime (CFPM), vancomycin, fosfluconazole, and famotidine—under conditions simulating co-administration through the side port of a continuous DOP infusion. Visual inspection, UV absorbance, pH measurement, and HPLC/UV analysis were performed at 0 and 3 h, with extended evaluation to 24 h for only MDZ and DLT. All mixtures showed acceptable physicochemical compatibility within 3 h, and MDZ and DLT remained stable for 24 h, indicating feasibility for co-infusion in the same syringe. In HPLC/UV analysis, the CFPM–DOP mixture exhibited a marked artifactual increase in DOP peak area, likely due to pH-dependent chromatographic behavior changing rather than true incompatibility. These findings provide practical compatibility data for NICU drug administration and offer a methodological framework for evaluating untested drug combinations, contributing to safer and more efficient intravenous therapy in preterm infants.