Intrathecal Ziconotide and Morphine for Pain Relief: A Case Series of Eight Patients with Refractory Cancer Pain, Including Five Cases of Neuropathic Pain.

INTRODUCTION Studies have shown that, at low doses and with careful titration, combination therapy with intrathecal ziconotide and morphine results in rapid control of opioid-refractory cancer pain. However, there is a lack of published data regarding the efficacy and safety of intrathecal ziconotide specifically for the treatment of neuropathic cancer pain. CASE SERIES Case reports of ziconotide intrathecal infusion in eight patients (age 45-71 years; 75% male) with chronic, uncontrolled cancer pain during therapy with intrathecal morphine plus bupivacaine were reviewed. Neuropathic pain was confirmed in five patients. Treatment was initiated with adjunctive ziconotide when pain ≥5 on a visual analog scale persisted in spite of 3 successive 20% dose increases of intrathecal morphine. Ziconotide was initiated at 0.5-1.0 µg/day, with mean increases of 0.5 µg every 4-7 days if required (maximum dose 10 µg/day; mean dose 4.9 µg/day). Pain intensity was reduced in all patients after 3-5 days. Of the eight patients, three died for reasons unrelated to ziconotide, three discontinued treatment due to adverse effects (predominantly psychoneurological disorders), and one patient is still receiving treatment. One patient discontinued ziconotide due to confusion and delirium. Due to continued lack of pain control with intrathecal morphine, intrathecal fentanyl was initiated; however, effective pain relief was not achieved with 1500 µg/day. Ziconotide was restarted and the patient then achieved pain control. CONCLUSION On the basis of our clinical experience, we recommend adding ziconotide to intrathecal opioid-based therapy in cancer patients with neuropathic pain inadequately controlled by intrathecal morphine alone. FUNDING Eisai, Spain.