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Objective: To determine the physicochemical stability of fentanyl in combination with midazolam and either hyoscine butylbromide or metoclopramide, and stored in 30 ml polypropylene syringes., Methods: Solutions containing approximately 40 microg/ ml of fentanyl in combination with midazolam (approximately 600 microg/ml) and either metoclopramide (approximately 700 microg/l) or hyoscine (approximately 850 microg/ml) were prepared from commercial ampoules of the drugs. The solutions were stored, in triplicate, in the dark at 32 degrees C (to simulate usage conditions) for 10 days, and the concentration of each constituent drug was periodically determined using a stability-indicating high-performance liquid chromatography assay., Results: The combinations were relatively stable, with all drugs maintaining over 90% of their initial chemical potency for at least 1 week. There were no evident changes in either the physical appearance or pH values of the solutions over the course of the study., Conclusions: On the basis of physicochemical stability, polypropylene syringes containing fentanyl with midazolam and either hyoscine butylbromide or metoclopramide can be safely prepared and stored at or below 32 degrees C for periods of up to 1 week prior to use by palliative care patients receiving the drugs via a portable subcutaneous infusion device.

Fentanyl and sufentanil are potent narcotic analgesics used only in hospitals as anaesthetic agents. The dependence potential of fentanyl is known. As they are given in doses at the microgram level and their elimination half-life is in the order of a few hours, detection in body fluids is possible only for a short time after administration. Radioimmunological methods are the only ones capable of detecting fentanyl in hair, as normal GC/MS methods for hair analysis are not sensitive enough to detect the drugs after doses in the order of micrograms. We therefore chose GC/MS/MS to analyse fentanyl and sufentanil in two cases where the drugs were given under controlled conditions over several days. The concentration was in the order of less than 100 pg/mg hair.