To determine the safety of hydromorphone hydrochloride solution for long term use in patient controlled analgesia by comparing the microbial contamination of preparations made under hospital ward dispensing room and pharmacy intravenous admixture service operating environment. Hydromorphone hydrochloride solutions were prepared in the patient controlled analgesia pump using 0.9 % sodium chloride under ward dispensing room or pharmacy intravenous admixture service operating environments. The solutions were stored at 25 degrees and 37 degrees and inspected for clarity and tested for bacterial endotoxin contamination for 15 d. The hydromorphone hydrochloride solution prepared under the ward dispensing room remained clear and endotoxin levels were below detection limits for 9 d. On d 11, this solution appeared turbid with slightly increased bacterial endotoxin levels. No remarkable observations were noted in the solution prepared under the pharmacy intravenous admixture service environment for the duration of the experiment. Hydromorphone hydrochloride solution prepared under the ward dispensing room conditions remained safe for use for only 9 d after preparation. On the other hand, the solution prepared under pharmacy intravenous admixture service remained suitable for use for longer as no contamination was observed for the duration of the study.