Intrathecal pumps for giving opioids in chronic pain: a systematic review

Ceasing intrathecal therapy in chronic non-cancer pain: an invitation to shift from biomedical focus to active management

Objective

To report long term experience (1997–2009) of intrathecal (IT) therapy for chronic non-cancer pain in the context of our team’s increasing emphasis on active management.

Design

Descriptive case series.

Setting

Australian tertiary multidisciplinary pain center, Hunter Integrated Pain Service (HIPS).

Intervention

This case series reports the changing use of IT implanted drug delivery systems (IDDSs) for chronic non-cancer pain over 13 years. Initially IT therapy was used selectively following multidisciplinary assessment and double blind IT trial. Typical therapy combined opioid with clonidine. Multidimensional management was offered. Treatment strategy changed in 2003 due to HIPS experience of limited therapeutic gains and equivocal support for IT therapy in the literature. Subsequently IT therapy was no longer initiated for non-cancer pain and those on established regimes were encouraged to shift to oral/transdermal opioids with greater emphasis on active management. Patient education and consultation were key elements. Where IT cessation was elective gradual dose reduction commenced as an outpatient. In elective and urgent cases ketamine infusion and oral clonidine were used during hospital admissions to cover the switch to oral/transdermal opioids. Over the study period transition occurred to a broader management framework in which IT therapy for chronic non-cancer pain was no longer supported by HIPS.

Results

25 patients were managed using IDDSs; 8 implanted by HIPS and 17 by other teams. Dose escalation and adverse effects were common. 24 of 25 patients ceased IT therapy; 7 (29%) with urgent IDDS related complications, 16 (67%) electively and 1 due to an unrelated death. The remaining patient returned to her original team to continue IT therapy. One post-explantation patient transferred to another team to recommence IT therapy. The remainder were successfully maintained on oral/transdermal opioids combined with active management.

Clinical management of pain in advanced lung cancer

Lung cancer is the most common cancer in the world and pain is its most common symptom. Pain can be brought about by several different causes including local effects of the tumor, regional or distant spread of the tumor, or from anti-cancer treatment. Patients with lung cancer experience more symptom distress than patients with other types of cancer. Symptoms such as pain may be associated with worsening of other symptoms and may affect quality of life. Pain management adheres to the principles set out by the World Health Organization's analgesic ladder along with adjuvant analgesics. As pain can be caused by multiple factors, its treatment requires pharmacological and non-pharmacological measures from a multidisciplinary team linked in with specialist palliative pain management. This review article examines pain management in lung cancer.

Neuraxial (epidural and intrathecal) opioids for intractable pain

1. Neuraxial opioids are considered for use in patients who have resistant intractable pain that fails to respond to other treatment options or pain that responds to analgesia but for which the doses required result in unacceptable side-effects. 2. Neuraxial opiods can be considered for both chronic non-malignant pain and chronic cancer-related pain. 3. Effectiveness in chronic non-malignant pain and cancer pain is exerted through the use of either single-agent drugs (opioids) or a combination of drugs: opioids, local anaesthetics and other drugs such as clonodine and ziconotide. 4. Complications of long-term continuous infusion therapy are related to the insertion process (haematoma), the mechanical device (both pump and catheter) and the long-term effects of the drugs. 5. Patients will require ongoing ambulatory monitoring and supportive care.

In vivo study of flow-rate accuracy of the MedStream Programmable Infusion System

OBJECTIVE

  Flow-rate accuracy and precision are important parameters to optimizing the efficacy of programmable intrathecal (IT) infusion pump delivery systems. Current programmable IT pumps are accurate within ±14.5% of their programmed infusion rate when assessed under ideal environmental conditions and specific flow-rate settings in vitro. We assessed the flow-rate accuracy of a novel programmable pump system across its entire flow-rate range under typical conditions in sheep (in vivo) and nominal conditions in vitro.

MATERIALS AND METHODS

  The flow-rate accuracy of the MedStream Programmable Pump was assessed in both the in vivo and in vitro settings. In vivo flow-rate accuracy was assessed in 16 sheep at various flow-rates (producing 90 flow intervals) more than 90 ± 3 days. Pumps were then explanted, re-sterilized and in vitro flow-rate accuracy was assessed at 37°C and 1013 mBar (80 flow intervals).

RESULTS

  In vivo (sheep body temperatures 38.1°C-39.8°C), mean ± SD flow-rate error was 9.32% ± 9.27% and mean ± SD leak-rate was 0.028 ± 0.08 mL/day. Following explantation, mean in vitro flow-rate error and leak-rate were -1.05% ± 2.55% and 0.003 ± 0.004 mL/day (37°C, 1013 mBar), respectively.

CONCLUSIONS

  The MedStream Programmable Pump demonstrated high flow-rate accuracy when tested in vivo and in vitro at normal body temperature and environmental pressure as well as when tested in vivo at variable sheep body temperature. The flow-rate accuracy of the MedStream Programmable Pump across its flow-rate range, compares favorably to the accuracy of current clinically utilized programmable IT infusion pumps reported at specific flow-rate settings and conditions.

Eliciting health state utilities from the general public for severe chronic pain

OBJECTIVE

There is an absence of data on public preferences for health states (HSs) associated with severe chronic pain. The aim of this study was to develop accurate HS descriptions for severe chronic pain requiring intrathecal (IT) therapy and to derive utility weights that describe the health-related quality of life (HRQL) impact of chronic pain associated with malignant (MP) and non-malignant (NMP) aetiologies.

RESEARCH DESIGN AND METHOD

Eight visual analogue scale pain index (VAS-PI) HSs were defined using ranges 0-40, 41-60, 61-80 and 81-100 applied to both MP and NMP. Additionally, eight HSs representing common adverse events associated with IT therapy were identified. The content and description of the HSs were ascertained by interviews with five United Kingdom clinical experts. In total, 16 HSs were compiled. These HS descriptions and HS questionnaires were administered to 102 members of the public, utilising a time trade off (TTO) approach to estimate utilities for the HSs.

RESULTS

Participants generally were well matched to the general public in England and Wales, with some differences in mean age, race and education. A substantial decline in utility was observed with more severe VAS-PI values. The mean TTO utility values also decreased from mild pain to severe pain. Participants were able to differentiate between the side effects.

CONCLUSION

The study shows a clear decrement in utility moving from different severity levels of severe chronic pain.

Cancer pain: part 2: physical, interventional and complimentary therapies; management in the community; acute, treatment-related and complex cancer pain: a perspective from the British Pain Society endorsed by the UK Association of Palliative Medicine and the Royal College of General Practitioners

OBJECTIVE

This discussion document about the management of cancer pain is written from the pain specialists' perspective in order to provoke thought and interest in a multimodal approach to the management of cancer pain, not just towards the end of life, but pain at diagnosis, as a consequence of cancer therapies, and in cancer survivors. It relates the science of pain to the clinical setting and explains the role of psychological, physical, interventional and complementary therapies in cancer pain.

METHODS

This document has been produced by a consensus group of relevant healthcare professionals in the United Kingdom and patients' representatives making reference to the current body of evidence relating to cancer pain. In the second of two parts, physical, invasive and complementary cancer pain therapies; treatment in the community; acute, treatment-related and complex cancer pain are considered.

CONCLUSIONS

It is recognized that the World Health Organization (WHO) analgesic ladder, whilst providing relief of cancer pain towards the end of life for many sufferers world-wide, may have limitations in the context of longer survival and increasing disease complexity. To complement this, it is suggested that a more comprehensive model of managing cancer pain is needed that is mechanism-based and multimodal, using combination therapies including interventions where appropriate, tailored to the needs of an individual, with the aim to optimize pain relief with minimization of adverse effects.

Drugs from slugs--past, present and future perspectives of omega-conotoxin research

Peptides from the venom of carnivorous cone shells have provided six decades of intense research, which has led to the discovery and development of novel analgesic peptide therapeutics. Our understanding of this unique natural marine resource is however somewhat limited. Given the past pharmacological record, future investigations into the toxinology of these highly venomous tropical marine snails will undoubtedly yield other highly selective ion channel inhibitors and modulators. With over a thousand conotoxin-derived sequences identified to date, those identified as ion channel inhibitors represent only a small fraction of the total. Here we discuss our present understanding of conotoxins, focusing on the omega-conotoxin peptide family, and illustrate how such a seemingly simple snail has yielded a highly effective clinical drug.

Cost-effectiveness of ziconotide in intrathecal pain management for severe chronic pain patients in the UK

OBJECTIVE

To examine the cost-effectiveness of using intrathecal ziconotide in the treatment of severe chronic pain compared to best supportive care for patients with intractable chronic pain in the United Kingdom.

METHODS

Using a simulation model, the analysis evaluated the cost and health economic consequences of using ziconotide as a treatment for severe chronic pain. The modelled population and clinical data were based on a randomised controlled trial in which the main outcome was reduction in pain as measured by the visual analogue scale of pain intensity (VASPI). Resource use data were elicited using a modified Delphi panel and costed using published sources. Utility values were derived from a separate research study. The main outcome measure was the cost per quality-adjusted life-year (QALY). Extensive scenario analysis was conducted to evaluate parameter uncertainty.

RESULTS

Overall, findings were robust to most assumptions. The cost-effectiveness of ziconotide compared to best supportive care (BSC) was pound 27,443 per QALY (95% CI pound 18,304-38,504). Scenarios were investigated in which discount rates, the time horizon, the threshold for qualifying as a responder, pump-related assumptions, utilities, ziconotide drug dose, and the patient discontinuation rate with ziconotide were varied. The most sensitive parameter was the dosage of ziconotide: using the lower and upper bounds of the average ziconotide dosage observed in the long-term open-label study changed the incremental cost-effectiveness ratio (ICER) to pound 15,500 [pound 8206-25,405] and pound 44,700 [pound 30,541-62, 670].

CONCLUSIONS

Ziconotide may offer an economically feasible alternative solution for patients for whom current treatment is inappropriate or ineffective. The main study limitation is that some model inputs, mainly related to resource use, are based on assumptions or expert interviews.

Ziconotide: an update and review

BACKGROUND

Ziconotide is the only N-type calcium channel blocker approved by the US FDA for the treatment of chronic pain. The approved indication is for the management of severe chronic pain in patients for whom intrathecal therapy is warranted and who are intolerant of or refractory to other treatments such as systemic analgesics, adjunctive therapies or intrathecal morphine.

OBJECTIVE

The purpose of this article was to review the available safety, efficacy and dosing information for ziconotide.

METHODS

The sources searched for literature from 1980 to January 2008 included Pub Med, MEDLINE and PREMEDLINE using the words ziconotide, conotoxins and pain.

RESULTS/CONCLUSION

Ziconotide is administered intrathecally by infusion pump to block nociceptive signal transmission in the spinal cord. It is a synthetic neuroactive peptide equivalent to the omega conotoxin MVIIA, a constituent of the venom of the fish-hunting marine snail Conus magus. It is highly potent, has a steep dose-response curve, a slow onset of action and a narrow margin of safety and responses to dose adjustments are slow. Patients receiving ziconotide should be under the care of physicians experienced in the management of intrathecal infusion therapy for pain control and should have convenient access to medical facilities.

Programmable intrathecal opioid delivery systems for chronic noncancer pain: a systematic review of effectiveness and complications

OBJECTIVES

We conducted a systematic review of the literature on the effectiveness and complications of programmable intrathecal opioid and ziconotide drug delivery systems (IDDS) for patients with chronic noncancer pain.

METHODS

We searched MEDLINE, Cochrane, and other bibliographic databases to identify English-language journal articles reporting programmable IDDS complications or effects on pain or functioning. Additional study methodology criteria were applied for the effectiveness review. Two authors independently abstracted data from each included article.

RESULTS

Six articles met the inclusion criteria for the effectiveness and complications reviews, and 4 others met the criteria only for the complications review; none were randomized trials or of ziconotide. All 6 articles reviewed for effectiveness reported improvement in pain and functioning on average among patients who received a permanent IDDS. Two articles reported the proportion of patients with > or =50% improvement in pain at 6 months (38%, 56%) and 2 at longer follow-ups (30%, 44%). Intrathecal morphine-equivalent doses increased over time. The most commonly reported permanent IDDS drug side effects were nausea/vomiting (mean rate weighted by sample size=33%), urinary retention (24%), and pruritus (26%). Catheter problems were also reported commonly. Rare but serious complications included intrathecal catheter tip granulomas.

CONCLUSIONS

The studies reviewed found improvement in pain and functioning on average among patients with chronic noncancer pain who received permanent IDDS. However, their methodologic limitations preclude conclusions concerning the effectiveness of this technology long-term and as compared with other treatments. Drug side effects and hardware complications were common. Suggestions are made for methodologic improvements in future studies.