Determination of compatibility and stability of drugs used in palliative care

Drugs for symptom control in the terminal phase of palliative patients may be used in pump systems.

To investigate the compatibility and stability of solutions of morphine hydrochloride, haloperidol, metoclopramide hydrochloride, atropine sulphate, butylhyoscine bromide and ranitidine hydrochloride, which may be used together under such circumstances.

Solutions of the drugs were exposed to ambient light at a temperature of 20 +/- 5 degrees C and +/- 31 degrees C for 24 h and 7 days and the solutions studied by ultraviolet spectrophotometry.

The combination of haloperidol or metoclopramide hydrochloride with different concentrations of morphine hydrochloride seemed to be compatible and stable. The concentration of atropine sulphate or butylhyoscine bromide could not be determined by the study method, but morphine hydrochloride seemed to be stable. The combination of ranitidine hydrochloride and morphine hydrochloride showed a change in colour after 7 days.

The results suggest that the combination of different concentrations of morphine hydrochloride with haloperidol, metoclopramide hydrochloride, atropine sulphate, butylhyoscine bromide or ranitidine hydrochloride do not affect their stability when stored for 7 days up to 30 degrees C under the influence of ambient light. However, more robust stability-indicating methods are required to confirm these results. The proposed method is more useful for identifying combinations that are clearly incompatible than to identify those that are compatible.