Background The delivery of intravenous medication by continuous infusion is necessary and widespread for treatment of patients with advanced cancer. Few scientific papers have focused on assessment of the chemical compatibility of these therapeutic mixtures. An analytical assessment of the physical and chemical compatibility of these combinations is needed.

Objectives To determine the chemical and physical compatibility of binary mixtures of metoclopramide (MET) and midazolam (MID).

Methods Mixtures of drugs were prepared under aseptic conditions in 0.9% sodium chloride at concentrations used in our clinical practice for continuous infusion. The samples were stored in polyethylene bags at room temperature in the presence of light for 15 days. Chemical compatibility was evaluated by high-performance liquid chromatography (HPLC). Physical compatibility was tested by visual inspection (for evidence of precipitation and colour change) and by pH determination.

Results No changes in colour, precipitation of components, measurable losses of volume or notable changes in pH were seen. The combinations tested were compatible for 15 days (retained >95% of their initial concentration).

Conclusions This study confirms the analytical compatibility of MET and MID, when mixed in 0.9% sodium chloride at concentrations employed in our clinical practice.