Stability and compatibility of hydromorphone hydrochloride in an implantable infusion system

With the exception of morphine, hydromorphone is the most commonly used intrathecal opioid for the treatment of intractable pain. The purpose of this study was to evaluate the stability and compatibility of hydromorphone in the implantable infusion system that is most commonly used in these patients. Hydromorphone solution was incubated at 37°C in infusion system reservoirs and with individual materials which comprise the fluid pathway of the infusion system. Stability was analyzed using high performance liquid chromatography; mechanical integrity of device materials was evaluated after drug exposure. After 4 months of exposure to device materials or intact devices, hydromorphone concentration remained greater than 95% of starting material. All device materials retained acceptable mechanical performance. These results demonstrate that hydromorphone is stable at physiological temperatures for at least 4 months in an implantable infusion system and that current clinical practice of refilling the pump every 3 months is appropriate.