Y-site compatibility of co-administered continuous infusion solutions in intensive care units: preparatory study on physicochemical compatibility of 28 relevant medicinal products

OBJECTIVES: Proven compatibility of multiple infusions administered Y-site through the same catheter lumen is crucial in intensive care patients. The aim of this study was to investigate the physicochemical compatibility of typically co-administered medicinal products (e.g. amiodarone, clonidine, dexmedetomidine, flucloxacillin, furosemide, heparin, ketamine, metamizole) for which specific data are lacking. METHOD: Forty-six binary 1:1 test admixtures of 28 medicinal products and concentrations taken from the German standardised concentration list for continuous infusion in intensive care patients were prepared. Test admixtures were stored at ambient temperature without light protection over a maximum period of 4 hours. Directly after mixing (t0), after 1 hour (t1) and after 4 hours (t4), admixtures were inspected for visible changes, subvisible particles were counted according to Ph. Eur. 2.9.19, pH values were measured and UV spectroscopy was performed at wavelengths 350 nm, 410 nm and 550 nm. Specifications for compatibility were set to no visible change, maximum 0.5 pH deviation from t0 to t4, maximum 0.1 deviation in UV absorbance from t0 to t4 at each wavelength, and subvisible particles ≤6000 (≥10 µm) and ≤600 particles (≥25 µm) at t0, t1 and t4. Admixtures were categorised as compatible when all specifications were fulfilled or incompatible when at least one specification was not fulfilled. RESULTS: In the experimental setting chosen, 30 of the 46 admixtures fulfilled all compatibility specifications set over the 4-hour observation period and were categorised as compatible. Sixteen admixtures, mostly containing dexmedetomidine, flucloxacillin, furosemide, heparin, ketamine and metamizole, failed the predefined specifications and were categorised as incompatible. In seven admixtures immediate precipitation/haze occurred and one became opalescent. Four admixtures showed noticeable deviations in pH and UV absorption. CONCLUSION: Y-site administration of 16 binary admixtures identified as incompatible is not recommended. The preparatory study results are suitable to complete incompatibility-reducing infusion schemes. Clinical pharmacists should implement incompatibility-reducing tools in intensive care patients.