Failure of epidural opioid to control cancer pain in a patient previously treated with massive doses of intravenous opioid

Implantable devices for pain control: spinal cord stimulation and intrathecal therapies

Untreated chronic pain is costly to society and to the individual suffering from it. The treatment of chronic pain, a multidimensional disease, should rely on the expertise of varying health care providers and should focus not only on the neurobiological mechanisms of the process but also on the psychosocial aspects of the disease. Implantable devices are costly and invasive, and such efficacious therapies should be used only when more conservative and less costly therapies have failed to provide relief of pain and suffering. Spinal cord stimulation provides neuromodulation of neuropathic, but not nociceptive, pain signals and when used for appropriate indications in the right individuals provides approximately 60-80% long-term pain relief in 60-80% of patients trialled for efficacy. Intrathecal therapies with opioids such as morphine, fentanyl, sufentanil or meperidine--or non-opioids such as clonidine or bupivacaine--provide analgesia in patients with nociceptive or neuropathic pain syndromes. Baclofen, intrathecally, provides profound relief of muscle spasticity due to multiple sclerosis, spinal cord injuries, brain injuries or cerebral palsy.

Evidence-based review of the literature on intrathecal delivery of pain medication

Evidence-based medicine depends on the existence of controlled clinical trials that establish the safety and efficacy of specific therapeutic techniques. Many interventions in clinical practice have achieved widespread acceptance despite little evidence to support them in the scientific literature; the critical appraisal of these interventions based on accumulating experience is a goal of medicine. To clarify the current state of knowledge concerning the use of various drugs for intraspinal infusion in pain management, an expert panel conducted a thorough review of the published literature. The exhaustive review included 5 different groups of compounds, with morphine and bupivacaine yielding the most citations in the literature. The need for additional large published controlled studies was highlighted by this review, especially for promising agents that have been shown to be safe and efficacious in recent clinical studies.

Hydromorphone-3-glucuronide: biochemical synthesis and preliminary pharmacological evaluation

Hydromorphone-3-glucuronide (H3G) was synthesized biochemically using rat liver microsomes, uridine-5'-diphosphoglucuronic acid (UDPGA) and the substrate, hydromorphone. Initially, the crude putative H3G product was purified by ethyl acetate precipitation and washing with acetonitrile. Final purification was achieved using semi-preparative high-performance-liquid-chromatography (HPLC) with ultraviolet (UV) detection. The purity of the final H3G product was shown by HPLC with electrochemical and ultraviolet detection to be > 99.9% and it was produced in a yield of = 60% (on a molar basis). The chemical structure of the putative H3G was confirmed by enzymatic hydrolysis of the glucuronide moiety using beta-glucuronidase, producing a hydrolysis product with the same HPLC retention time as the hydromorphone reference standard. Using HPLC with tandem mass spectrometry (HPLC-MS-MS) in the positive ionization mode, the molecular mass (M+1) was found to be 462 g/mol, in agreement with H3G's expected molecular weight of 461 g/mol. Importantly, proton-NMR indicated that the glucuronide moiety was attached at the 3-phenolic position of hydromorphone. A preliminary evaluation of H3G's intrinsic pharmacological effects revealed that following i.c.v. administration to adult male Sprague-Dawley rats in a dose of 5 microg, H3G evoked a range of excitatory behavioural effects including chewing, rearing, myoclonus, ataxia and tonic-clonic convulsions, in a manner similar to that reported previously for the glucuronide metabolites of morphine, morphine-3-glucuronide and normorphine-3-glucuronide.

Neuropathic pain in cancer patients: mechanisms, syndromes, and clinical controversies

The identification of a neuropathic pain syndrome in a cancer patient requires a focused clinical evaluation based on knowledge of common neuropathic pain syndromes. If a tumor is directly involved in the etiology of the pain, oncologic treatment is an initial consideration and may include surgery, radiation, or chemotherapy. There is no single accepted algorithm for the analgesic treatment of neuropathic pain and a systematic approach utilizing therapeutic trials of specific agents at gradually increasing doses is warranted. A trial of opioids, perhaps in combination with an NSAID, is warranted. If the pain is relatively unresponsive to an opioid, a trial with an adjuvant analgesic is reasonable. For example, a tricyclic antidepressant might be selected early for patients with continuous dysesthesia, and early treatment with an anticonvulsant might be used if the pain is predominantly lancinating or paroxysmal. Other adjuvant analgesics can be selected if there is insufficient response to these agents. A trial of sympathetic blockade, pharmacologic, anesthetic or surgical, should be considered in patients with evidence of causalgia or reflex sympathetic dystrophy. Physiatric modalities such as massage, heat, or cold; counterstimulation or transcutaneous electrical nerve stimulation (TENS), and orthopedic interventions, such as braces and splints may be useful. Epidural injections or neurostimulation of the spinal cord or brain can be considered in selected cases where appropriate expertise is available. Treatment of neuropathic pain remains a challenge for both clinicians and patients. The complexity of syndromes and underlying etiologic mechanisms warrants further clinical trials to determine the best treatment modalities for individual pain syndromes.

Pain management in patients with pancreatic carcinoma

Pancreatic cancer has a very poor prognosis and is often associated with severe pain. A variety of pain syndromes and pain pathophysiologies can be identified. Information about the analgesic efficacy of available oncological treatments is very limited, but the available data suggest that pharmacological and non-pharmacological approaches can be effective in the majority of cases. Guidelines have been developed for drug administration that emphasize indications, selection of routes, optimal dosing, and side effect treatment. Celiac plexus block can be considered for a subgroup of patients who fail to benefit from drug therapy. Optimally, pain management should be provided within a broader model of palliative care, which can address the many problems associated with this challenging disease.

Intraspinal opioid therapy for chronic nonmalignant pain: current practice and clinical guidelines

The multidimensional nature of chronic nonmalignant pain lends itself to numerous treatment options, which vary in cost and invasiveness. Based on the principle that less invasive and less costly interventions for pain treatment should be attempted first, a continuum of interventions for chronic pain states is presented. Although intraspinal opioid therapy is a relatively invasive and costly modality for pain treatment, it has a rational place in the treatment continuum for some chronic nonmalignant pain patients. A thorough review of the literature, supplemented by clinical experience, provides a foundation for the development of management guidelines.

Outcomes of epidural morphine treatment in cancer pain: nine years of clinical experience

The outcome of epidural morphine therapy is described in 146 consecutive cancer patients who were treated by a community hospital-based pain service. The routine procedure used a standard epidural catheter that was tunneled subcutaneously. One hundred and twenty-one patients improved and stayed on lifelong or chronic epidural opioids. Mean treatment time was 92 days (median, 47; range, 2-2040); 49% of the time was spent as outpatients. Twenty-five patients failed to respond to the treatment. The oral daily morphine-equivalent dose prior to inclusion was 164 mg. The mean daily epidural start dose of morphine was 18 mg (range, 6-120), and the mean daily dose at termination was 69 mg (range, 2-540). The dose escalations, described as the ratio of the maximum dose to the minimum maintenance start dose, were moderate, with a mean of 4.1 (median, 2.5), which corresponded to a percent increase of 5.1 (median, 2.7) per patient per day. Lack of effect due to the character of the original symptoms or progression of pain was the main reason for withdrawal from epidural opioid therapy (N = 27), followed by catheter-related problems (N = 9) and drug-related complications (N = 5). Also due to drug-related complications, epidural morphine therapy was changed to buprenorphine or methadone in 19 patients. Adjuvant systemic opioids were given to ten patients and epidural local anesthetics were administered to 17 of the subjects. Neuropathic pain, certain visceral pain types, incident pain on movement, and pain from cutaneous ulcerations were characteristics of poor responders.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrathecal infusional analgesia for nonmalignant pain: analgesic efficacy of intrathecal opioid with or without bupivacaine

We report on the analgesic efficacy of intrathecal infusions of opioids alone or in combination with bupivacaine in 16 nonmalignant pain patients with implanted pumps. Three patients had nociceptive pain, five had neuropathic pain, and 8 had mixed pain syndromes. Infusional therapy was delivered over a combined monthly total of 445 mo of therapy (mean, 27.8 mo). Dose requirements appeared to be stable with a mean dose increase of 0.26 mg/mo. Bupivacaine was added to the opioid to enhance pain control in 13 patients who received combination therapy for an average of 11.7 mo/patient. Thirteen patients (81%) reported good to excellent results with opioid alone or opioid combined with bupivacaine. The addition of bupivacaine improved analgesia in two of three patients with nociceptive pain (66.7%), compared to eight of ten patients with a pure or mixed neuropathic component to their pain (80%). We conclude that intrathecal opioids alone or in combination with bupivacaine are efficacious for the treatment of nonmalignant pain states and are relatively free of significant side effects or tolerance.

Intrathecal infusional therapies for intractable pain: patient management guidelines

This article focuses on appropriate patient selection for and management of patients selected for continuous spinal infusional opioid therapy. Patients with cancer-related pain who have undergone sequential strong opioid drug trials, who have intractable, unmanageable side effects, and who have undergone a successful spinal opioid efficacy trial are candidates for implantable spinal infusional therapy. Patients with noncancer-related chronic pain, who have failed all conventional syndrome-specific therapies before neuroablative surgical procedures, including sequential strong opioid drug trials, who have intractable, unmanageable side effects, and who have undergone successful spinal opioid efficacy trial are deemed candidates for implantable spinal infusional therapy. Patients with chronic noncancer-related pain and patient with cancer-related pain who have life expectancies greater than 3 mo all have implanted programmable infusion pumps. Patients with cancer-related pain who have life expectancies less than 3 mo have implanted permanent epidural catheters connected to external pump systems. Management guidelines for complications of therapy broadly categorized as surgical, mechanical, and pharmacologic are presented.

The management of intractable bone pain: a clinician's perspective

Bone metastases occur in up to 85% of patients (at autopsy) who have breast, lung, and prostate cancer, and are a common cause of pain and neurological morbidity in patients with these and other cancers. The management of pain, the most common complication of bone metastasis, requires a knowledge of specific clinical syndromes and the associated neurological and orthopedic morbidities, as well as an understanding of current antitumor and pharmacological therapies. Knowledge of these potential complications are important in the design of clinical trials that seek to evaluate the effectiveness of new treatments for bone metastasis. Although radiation therapy in combination with analgesic drug therapies remains the mainstay of treatment, much recent interest in drugs with specific effects on bone elements, especially the osteoclast, offer the promise of providing effective pain relief with fewer side effects than is currently possible with conventional therapies.