Intrathecal drug administration in chronic pain syndromes.

Chronic pain may recur after initial response to strong opioids in both patients with cancer and patients without cancer or therapy may be complicated by intolerable side effects. When minimally invasive interventional pain management techniques also fail to provide satisfactory pain relief, continuous intrathecal analgesic administration may be considered. Only 3 products have been officially approved for long-term intrathecal administration: morphine, baclofen, and ziconotide. The efficacy of intrathecal ziconotide for the management of patients with severe chronic refractory noncancer pain was illustrated in 3 placebo-controlled trials. A randomized study showed this treatment option to be effective over a short follow-up period for patients with pain due to cancer or AIDS. The efficacy of intrathecal opioid administration for the management of chronic noncancer pain is mainly derived from prospective and retrospective noncontrolled trials. The effect of intrathecal morphine administration in patients with pain due to cancer was compared with oral or transdermal treatment in a randomized controlled trial, which found better pain control and fewer side effects with intrathecal opioids. Other evidence is derived from cohort studies. Side effects of chronic intrathecal therapy may either be technical (catheter or pump malfunction) or biological (infection). The most troublesome complication is, however, the possibility of granuloma formation at the catheter tip that may induce neurological damage. Given limited studies, the evidence for intrathecal drug administration in patients suffering from cancer-related pain is more compelling than that of chronic noncancer pain.

Intrathecal therapy: what has changed with the introduction of ziconotide.

Administering drugs into the intrathecal space is becoming more popular in the treatment of patients with intractable pain or intolerable side effects of systemic analgesic treatments. Although morphine and ziconotide are the only intrathecal analgesics currently approved by regulatory authorities in the U.S. (Food and Drug Administration) and Europe (national-level approval by individual countries for morphine and European Agency for the Evaluation of Medicinal Products approval for ziconotide), a wide variety of opioid and non-opioid drugs are being used in this way. There is no official guidance concerning the selection of these drugs or their use in combinations and a paucity of efficacy and safety data from randomized controlled trials. The polyanalgesic initiative aims to summarize the current knowledge and to facilitate rational choices of intrathecal drug and drug combinations for the management of chronic pain. The most recent polyanalgesic consensus recommendations were published in 2007. In this review, we shall examine these recommendations, which are tailored toward those practicing intrathecal analgesia in the U.S., and discuss how they should be implemented in Europe, where the healthcare systems and regulations of the medical authorities are different.

Management of intrathecal catheter-tip inflammatory masses: an updated 2007 consensus statement from an expert panel.

Background. Expert panel of physicians and nonphysicians, all expert in intrathecal (IT) therapies, convened in the years 2000 and 2003 to make recommendations for the rational use of IT analgesics based on the preclinical and clinical literature known up to those times, presentations of the expert panel, discussions on current practice and standards, and the result of surveys of physicians using IT agents. An expert panel of physicians and convened in 2007 to review previous recommendations and to form recommendations for the rational use of IT agents as they pertain to new scientific and clinical information regarding the etiology, prevention and treatment for IT granuloma. Method. A review of preclinical and clinical literature from 2000 to 2006 was undertaken and disseminated to an expert panel of physicians. Focused discussions concerning the rational use of IT agents and its relationship to the etiology of, prevention of, and treatment of IT granuloma were held. Results. This report presents here new knowledge of the etiology of catheter tip granuloma and guidelines for its prevention and treatment.

Future directions for intrathecal pain management: a review and update from the interdisciplinary polyanalgesic consensus conference 2007.

Background. Expert panels of physicians and nonphysicians, all expert in intrathecal (IT) therapies, convened in the years 2000 and 2003 to make recommendations for the rational use of IT analgesics, based on the preclinical and clinical literature known up to those times, presentations of the expert panels, discussions on current practice and standards, and the result of surveys of physicians using IT agents. An expert panel of physicians and nonphysicians has convened in 2007 to update information known regarding IT therapies and to update information on new and novel opioid and nonopioid analgesic compounds that might show promise for IT use. Methods. A review of preclinical and clinical published relevant studies from 2000 to 2006 was undertaken and disseminated to a convened expert panel of physicians and nonphysicians to discuss new and novel analgesic agents for IT use. Results. The panelists identified several agents that were worthy of future studies for the clinical and rational use of IT agents that are presented in this article. Conclusions. A list of nonopioid IT analgesics, including gabapentin, adenosine, octreotide, the χ-conopeptide, Xen2174, the conopeptide, neurotensis 1 agonist, CGX-1160, the ω-conotoxin, AM-336, and physostigmine, were identified as worthy of future research by the panelists.

An Open-Label, Multicenter Study of the Safety and Efficacy of Intrathecal Ziconotide for Severe Chronic Pain When Delivered via an External Pump.

Objectives. The study aims to assess the safety and efficacy of intrathecal (IT) ziconotide when delivered via an external infusion system. Materials and Methods. Patients with severe chronic pain were implanted with an external infusion system, and IT ziconotide was titrated over one to four weeks. Safety was evaluated via adverse event (AE) reports, and efficacy measures included the visual analog scale of pain intensity (VASPI), categorical pain relief scale (CPRS), and clinical global impression (CGI). Results. Sixty-four of the 71 patients (90.1%) experienced an AE during titration; five patients developed meningitis after completing at least two weeks of therapy. A significant (p ≤ 0.005) median percentage improvement in VASPI scores was seen at week 1 and maintained through week 4 (range: 11.0-32.6%); 53.6% of patients reported good to excellent pain control on the CGI and 52.2% of patients reported moderate to complete pain relief on the CPRS. Conclusions. The study results suggest that a short-term trial of IT ziconotide using an external infusion system may be sufficient to assess patient response. High rates of AEs were noted; however, ziconotide-related AEs were consistent with those reported in previous trials.

A Prospective, Open-label Study of Long-term Intrathecal Ziconotide for Chronic Nonmalignant Back Pain: A Case Report.

Ziconotide is an N-type calcium channel (NCC) blocking conopeptide, acting primarily at the NCC-rich dorsal horn. Reported here is an early experience with intrathecal ziconotide in a 55-year-old man with chronic pain resulting from failed back surgery. All conservative and surgical treatments, in addition to IT morphine, failed prior to enrollment in a short-term, placebo-controlled trial testing ziconotide efficacy and safety. Following successful short-term treatment, the patient was enrolled in a long-term follow-up study. The dosing regimen, onset and resolution of adverse events, and improvement on the primary efficacy measure, the Visual Analog Scale of Pain Intensity, are discussed. Overall, the patient responded positively to ziconotide.