Background In order to avoid separate injections, admixtures of drugs are frequently used in palliative care settings. There is a lack of evidence about the stability and compatibility of the combination of hyoscine N-butyl bromide and furosemide

Purpose To evaluate the compatibility and stability of three admixtures of hyoscine N-butyl bromide and furosemide at different concentrations and at two temperatures (25°C and 37°C) in NaCl 0.9% stored in elastomeric infusors protected from light.

Material and methods The samples were prepared and diluted in NaCl 0.9% in elastomeric infusors in triplicate to obtain six different conditions of concentration and/or temperature of storage (concentration: 2.0 mg/ml–2.0 mg/ml, 1.0 mg/ml–0.6 mg/ml and 0.6 mg/ml–0.6 mg/ml of hyoscine N-butyl bromide and furosemide respectively; temperature 25°C and 37°C).

The concentration of each constituent drug was periodically determined using a HPLC-UV method. The drugs were chromatographed on a C₁₈ reverse phase column and determined at 220 nm by interpolation from the calibration curves prepared at (0, 1, 2, 3, 7, 11, 15, 20) days from the standards; the mobile phase was acetonitrile-water 80:20 (v/v); flow rate 1.5 ml/min.

Results The stability of the admixtures diluted in NaCl 0.9% were as follows: hyoscine N-butyl bromide-furosemide (2.0 mg/ml–2.0 mg/ml) was stable (retained >95% of their initial concentrations) two days at 25°C and 37°C; (1.0 mg/ml–0.6 mg/ml) was stable eight days at 25°C and two days at 37°C; (0.6 mg/ml–0.6 mg/ml) was stable twelve days at 25°C and three days at 37°C.

Conclusion The admixture of hyoscine N-butyl bromide and furosemide in NaCl 0.9% in elastomeric infusor can be safely used in palliative care for at least two days. Lower concentrations of the admixture can be prepared in advance and stored at room temperature, but the infusion cannot take longer than three days.

References and/or acknowledgements No conflict of interest.