Compatibility and stability of tramadol and dexamethasone in solution and its use in terminally ill patients

Background: Delivery of drug admixtures by continuous subcutaneous infusion is common practice in palliative medicine, but analytical confirmation of their compatibility and stability is not always available. Objective: To study the compatibility and stability of tramadol hydrochloride and dexamethasone sodium phosphate combined in solution and to report on its use in terminally ill patients. Method: Twelve different solutions containing tramadol hydrochloride (8.33-33.33 mg/mL) and dexamethasone sodium phosphate (0.33-3.33 mg/mL) were prepared in saline and stored in polypropylene syringes for 5 days (25 degrees C). Analysis was performed on days 1, 3 and 5 days with simultaneous determination by HPLC. pH was measured at 0 and 5 days. Clinical performance was assessed retrospectively in six terminal-ill oncology patients. Results: Maximum losses of 7% and 6% were observed for tramadol and dexamethasone. Pain was completely controlled in four patients. Local tolerance resulted in haematoma in three patients, which resolved by switching to a butterfly insertion site. Conclusion: Tramadol hydrochloride (100-400 mg/day) and dexamethasone sodium phosphate (4-40 mg/day) are stable for at least 5 days when combined in saline and stored at 25 degrees C. These results are only valid for the type of syringes and the specific commercial preparations tested.