Open AccessContinuous Intrathecal Infusion of Hydromorphone: Safety in the Sheep Model and Clinical Implications
Author(s) -
Johansen Mary J.,
Satterfield William C.,
Baze Wallace B.,
Hildebrand Keith R.,
Gradert Tamara Lee,
Hassenbusch Samuel J.
Publication year - 2004
Publication title -
pain medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.893
H-Index - 97
eISSN - 1526-4637
pISSN - 1526-2375
DOI - 10.1111/j.1526-4637.2004.04010.x
Subject(s) - hydromorphone , medicine , anesthesia , lumbar , saline , spinal cord , catheter , morphine , intrathecal , surgery , opioid , receptor , psychiatry
Objective. To determine the safety of hydromorphone delivered by continuous intrathecal infusion via implanted delivery systems in sheep. Design. Sheep implanted with intrathecal infusion systems were randomly assigned to receive either 1.5, 3, or 6 mg/day hydromorphone HCl or saline control (3 sheep/dose level) at a fixed infusion rate of 1.92 mL/day for 28–31 days. Infusions were initiated approximately 5 days after surgical implantation of the delivery systems (pumps and intrathecal catheters), and investigators were blinded to doses administered. An additional group of sheep (N=3) received hydromorphone (open label) at a dose of 12 mg/day. All animals were examined daily during drug infusion for changes in behavior and neurologic function. Cerebrospinal fluid was analyzed for protein, cytology, and hydromorphone concentration in samples collected prior to and at the end of drug infusion. The spinal cord with the catheter in situ was removed en bloc and fixed in formalin for microscopic analysis. Results. All sheep receiving intrathecal hydromorphone exhibited gaiting deficits and biting behavior over the caudal lumbar area above the infusion site. Animals treated with 12 mg/day were sedate and lethargic, and exhibited repeated biting behavior over the caudal lumbar area during the study. No lesions were noted in any animal upon gross evaluation of the spinal cord. Microscopic changes were comparable between hydromorphone‐ and saline‐treated animals with one exception. Mild inflammation 5 cm cranial to the catheter tip was present in two of three sheep receiving 12 mg/day and in one of three sheep receiving 1.5 mg/day. Mild chronic inflammation hydromorphone in the vicinity of the catheter was also presented in saline‐treated animals. Conclusions. Hydromorphone was not associated with inflammatory mass formation in the sheep model. Further studies are necessary to determine whether hydromorphone is a safer alternative to morphine for continuous intrathecal infusion for the treatment of chronic pain.