Physical Compatibility of Intravenous Ondansetron Hydrochloride and Nafcillin Sodium

Information on the physical compatibility of intravenous (IV) medications is vital for patient care and safety in acute care settings. Drug information resources list ondansetron and nafcillin as IV compatible, however, bolus concentrations of ondansetron are not reported. This study investigated the in vitro physical compatibility of bolus and infusion concentrations of ondansetron hydrochloride with nafcillin sodium. Two admixtures were prepared: 1) ondansetron hydrochloride 2 mg/mL and nafcillin sodium 20 mg/mL, and 2) ondansetron hydrochloride 0.16 mg/mL and nafcillin sodium 20 mg/mL. The admixtures were prepared in triplicate using aseptic technique according to manufacturer guidance and stored at room temperature (22-23 °C) for up to 24 hours. Admixtures were examined for visual precipitation, turbidity, and pH at baseline and at 1, 5, 8, and 24 hours. Admixture 1 developed a haze immediately after mixing, which was sustained over 24 hours. There was a demonstrative change in absorbance after 1 hour, but pH remained stable until hour 24. Admixture 2 developed a haze at 5 hours, but the absorbance and pH remained stable until hour 24; a decrease in the pH was observed in all samples at hour 24. This in vitro study revealed that ondansetron hydrochloride 2 mg/mL and nafcillin sodium 20 mg/mL are not physically compatible when administered through the same IV line. No demonstrative change was observed with ondansetron hydrochloride 0.16 mg/mL and nafcillin sodium 20 mg/mL; however, concurrent administration of these medications is questionable when delivered through an IV line for periods of five hours or longer.