Compatibiliity and stability of furosemide and dexamethasone combined in infusion solutions

The goal of palliative care is the achievement of the best quality of life for patients and their families. For this, the administration of drugs by subcutaneous infusion is frequently used since many patients have great difficulties in taking drugs orally and regular intramuscular injections are painful. Usually, drugs are combined in infusion solutions. The objective was therefore to study the compatibility and stability of dexamethasone sodium phosphate (CAS 2392-39-4) and sodium furosemide (CAS 54-31-9) combined in solutions destined to subcutaneous administration in palliative medicine.

Twelve different solutions were assessed during 15 days. Drug admixtures were prepared in polypropylene syringes using 0.9 % saline as diluent and stored at 4 degrees C and 25 degrees C in the dark. Initial concentrations were 3.33-10.0 mg/ ml for sodium furosemide (dose range 40-120 mg/day) and 0.33-3.33 mg/ml (dose range 4-40 mg/day) for dexamethasone sodium phosphate. Quantification of both drugs was performed by high-performance liquid chromatography.

After 5 days of storage at both temperatures, the maximum losses obtained were lower than 10 % for both drugs. However, after 15 days, slight precipitation/turbidity was observed in all mixtures. At this time, maximum losses of 20 % were obtained for both drugs.

These results confirm the stability of mixtures prepared with sodium furosemide (< or = 120 mg/day) and dexamethasone sodium phosphate (< or = 40 mg/day) for a period of 5 days and with independence of their storage at 4 degrees C or 25 degrees C.