Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Morphine and hydromorphone infusions of 6 or more (average 25.75) days in duration were used with increasing frequency (up to 7%) by our oncology inpatients. Eighty-six percent of the 135 inpatients we reviewed realized good pain control with dose rates up to 700 morphine-equivalent (ME) mg/h. Local toxicity occurred on only 10 occasions. Systemic side effects secondary to the infusion were reported 75 times and were generally readily reversed. Myoclonus was seen in 11% of our patients at dose rates as low as 60-90 ME mg/h. Adjuvant therapies were not used as frequently as might be warranted. We believe that narcotic infusions, particularly subcutaneous ones, are safe and effective. Further prospective trials are needed to clarify how they should be combined with other therapies to control cancer pain that is poorly responsive to narcotics, and to better understand the etiology and management of serious side effects.
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PMID:Inpatient narcotic infusions for patients with cancer pain. 169 50

This case report describes a patient affected by a neuropathic pain syndrome, which was secondary to a renal cell carcinoma metastatic to the spine, and complicated by incidental components and somatization. Due to a rapid development of tolerance and toxicity from hydromorphone, a rotation to methadone was made, with a decrease of the morphine equivalent daily dose (MEDD) from 1050 to 36. After 4 mos of good pain relief, a switch over back to hydromorphone was necessary due to worsening pain, associated with myoclonus and sedation secondary to methadone; the MEDD this time escalated from 480 to 4950. The use of hydromorphone was complicated by the onset of intractable nausea and sedation. After 2 wks, the patient was rotated again to methadone, with a decrease of the MEDD to 24. He achieved good pain control and was free of opioid toxicity. Our findings illustrate a role of methadone in the management of cancer pain associated with poor prognostic indicators, the development of tolerance towards its effects, and the regaining of sensitivity to methadone, by temporary rotation to another opioid. Possible mechanism for opioid tolerance and its reversal are discussed.
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PMID:Individualized use of methadone and opioid rotation in the comprehensive management of cancer pain associated with poor prognostic indicators. 889 38

A 62-year-old man receiving subcutaneous fentanyl for the management of cancer pain developed generalized central excitation after an overdose of 5000 micrograms of fentanyl. The patient developed acute confusion, restlessness, generalized myoclonus, visual hallucinations, and hyperalgesia and tremors upon tactile stimulation of the arms or legs. These symptoms rapidly disappeared after the administration of 0.2 mg of naloxone. Within an hour the symptoms reappeared and once again, responded immediately after a second injection of 0.2 mg of naloxone. Our findings suggest that fentanyl overdose can occasionally present with general central irritability that responds to naloxone.
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PMID:Acute neuropsychiatric findings in a patient receiving fentanyl for cancer pain. 906 31

Pain occurs in more than 80% of cancer patients before death. Because of the increase in the frequency of cancer deaths worldwide, it is imperative to address cancer pain as a public health problem. Until recently, educational efforts were focused on treatment issues rather than adequate assessment. The approach to pain intensity as a multidimensional construct has helped in focusing treatments and identifying prognostic factors. Valid tools have been developed that allow multidisciplinary assessment of these prognostic factors and their complex interrelationship with the analgesic response. As a result of increased opioid exposure, patients are currently developing newer toxicities, mostly central excitability including delirium, myoclonus, grand mal seizures, and hyperalgesia. The observation that more than 80% of patients will require alternate routes for opioid delivery before death led to the development of a number of novel and effective alternate routes for delivery. Finally, in recent years it has become evident that some specific pain syndromes need to be addressed using specific assessment and management techniques. Incidental pain, somatization, neuropathic pain, and cancer pain in patients with alcoholism and drug addiction are some of these syndromes.
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PMID:Cancer pain management. 906 Oct 98

A case of severe opioid toxicity is described in a 52-year-old cancer patient. The patient presented with classical clinical features of central hyperexcitability associated with opioid toxicity: delirium, myoclonus, hallucinations, hyperalgesia, and a possible seizure. This patient had a background of severe psychosocial distress and somatization in addition to a history of benzodiazepine dependence and alcohol abuse. The occurrence of opioid toxicity in this patient highlights the risks of a unidimensional approach to cancer pain, which ignores the non-organic components of pain, such as psychosocial distress, which will not respond to escalating doses of opioid medication.
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PMID:Severe opioid toxicity and somatization of psychosocial distress in a cancer patient with a background of chemical dependence. 920 57

Pain affects most patients with malignant disease, and the prevalence of severe pain increases in the advanced stages of the condition. One in 5 patients with cancer has uncontrolled pain, even after 10 years of the use of the World Health Organization programme for cancer pain control and its 'three-step ladder' for the rational use of analgesics including morphine. Morphine has long been the 'gold standard' for the treatment of severe cancer pain. However, its side-effects, particularly sedation, cognitive impairment and myoclonus at high doses, have provoked the use of 'opioid rotation' to alternatives such as methadone and hydromorphone. The new 72-h transdermal patch for fentanyl also offers advantages of reduced side-effects and increased convenience over oral morphine. Intravenous strontium-89 and bisphosphonate therapy are effective for both short- and long-term control of metastatic bone pain. The spinal N-methyl-D-aspartate (NMDA) receptor is important in modulating the plasticity of the central nervous system and in aggravating chronic pain through the phenomenon of 'wind-up'. The NMDA antagonist ketamine, an anaesthetic, can be used at low doses for the management of refractory and neuropathic pains. Among adjuvant drugs, ketorolac has emerged as a potent non-steroidal anti-inflammatory drug. Palliative care is gaining acceptance as a new discipline in healthcare. Its strategic role is being reviewed as an adjunct to cancer therapy at all stages and its use is no longer confined to the terminal phase of disease after curative treatment has failed. Pain control and other aspects of symptom control are, therefore, viewed as an integral part of cancer management.
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PMID:New approaches to pain control in patients with cancer. 940 34

Myoclonus occasionally occurs in the perioperative setting and in patients on chronic opioid therapy. It appears to be dose-related in a unpredictable manner. Different mechanisms have been proposed to explain the occurrence of a series of neuromuscular disturbances probably sharing final common pathways. A neuroexcitatory opioid metabolite accumulation has been proposed to have a relevant role in determining myoclonus in patients treated with chronic opioid therapy for cancer pain, especially in the presence of renal impairment. The neurological status, previous oncologic treatment and concomitant therapy with neuroleptic drugs, the metabolic and hydration status should also have been considered. Adjuvant drugs, such as benzodiazepines or dantrolene may avoid the reduction of the opioid dose while maintaining an acceptable analgesia. Current practice suggests a change in opioid when pain control is not obtained at opioid doses resulting in unacceptable adverse effects, including myoclonus and hyperalgesia. A change in the type of opioid may be useful in patients who develop severe central adverse effects, even if these patients appear to have normal renal function or hydration status.
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PMID:Pathophysiology and treatment of opioid-related myoclonus in cancer patients. 951 54

The majority of cancer patients develop pain before death. This pain has been shown to be underdiagnosed and undertreated. Opioid use has increased in the past 20 years in both developing and developed countries. The changing pattern in opioid use has resulted in the emergence of neurotoxicity as a major side effect of the treatment of cancer pain. The syndrome of opioid-induced neurotoxicity (OIN) encompasses delirium, hallucinosis, myoclonus/seizures and hyperalgesia. Increased vigilance can lead to the timely diagnosis of OIN, and strategies for its treatment can be implemented with encouraging results. Identification and modification of risk factors for the development of OIN can help in its prevention and improve the quality of life in advanced cancer patients.
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PMID:Opioid use in cancer pain. Is a more liberal approach enhancing toxicity? 1052 40

1. Morphine is recommended by the World Health Organization as the drug of choice for the management of moderate to severe cancer pain. 2. Education of health professionals in the past decade has resulted in a large increase in the prescribing of opioids, such as morphine, and in the magnitude of the doses administered, resulting in an improvement in the quality of pain relief available for many cancer patients. 3. However, the reported incidence of neuroexcitatory side effects (allodynia, myoclonus, seizures) in patients administered large doses of systemic morphine or its structural analogue, hydromorphone (HMOR), has also increased. 4. Clinically, increasing the magnitude of the morphine or HMOR dose administered to patients already exhibiting neuroexcitatory opioid related side effects, results in an exacerbation rather than an attenuation of the excitatory behaviours. 5. In contrast, cessation of the opioid or rotation to a structurally dissimilar opioid (e.g. from morphine/HMOR to methadone or fentanyl), usually results in a restoration of analgesia and resolution of the neuroexcitatory opioid side effects over a period of hours to days. 6. To explain the clinical success of 'opioid rotation', it is essential to understand the in vivo metabolic fate of morphine and HMOR. 7. Following systemic administration, morphine and HMOR are metabolized primarily to the corresponding 3-glucuronide metabolites, morphine-3-glucuronide (M3G) and hydromorphone-3-glucuronide (H3G), which are not only devoid of analgesic activity but evoke a range of dose-dependent excitatory behaviours, including allodynia, myoclonus and seizures, following intracerebroventricular (i.c.v.) administration to rats. 8. Several studies have shown that, following chronic oral or subcutaneous morphine administration to patients with cancer pain, the cerebrospinal fluid (CSF) concentrations of M3G exceed those of morphine and morphine-6-glucuronide (analgesically active morphine metabolite) by approximately two- and five-fold, respectively. 9. These findings suggest that when the M3G concentration (or H3G by analogy) in the CSF exceeds the neuroexcitatory threshold, excitatory behaviours will be evoked in patients. 10. Thus, rotation of the opioid from morphine/HMOR to a structurally dissimilar opioid, such as methadone or fentanyl, will allow clearance of M3G/H3G from the patient central nervous system over hours to days, thereby producing a time-dependent resolution of the neuroexcitatory behaviours while maintaining analgesia with methadone or fentanyl.
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PMID:Neuroexcitatory effects of morphine and hydromorphone: evidence implicating the 3-glucuronide metabolites. 1087 11

The occurrence of undesirable side effects due to opioids (delirium, confusion, myoclonus, nausea, emesis) is one of the major complications in the management of pain, especially in chronic cancer pain states. Methadone, as an alternative to morphine, has been proposed in the control of opioid-induced toxicity. Methadone is a synthetic opioid, with mu and delta receptor activity, associated with the capacity to inhibit N-methyl-D-aspartate receptors. Questions have arisen concerning its equianalgesic ratio since its rediscovery over the past few years and are certainly related to its receptor interactions. Aspects of its pharmacology, indications, and switching modalities are discussed here. Opioid rotation is a new tool in the management of cancer pain, deserving more attention.
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PMID:Opioid switch to oral methadone in cancer pain. 1088 15


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