Journal of pain and symptom management
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J Pain Symptom Manage · Jan 2000
Clinical TrialThe safety and efficacy of a single dose (500 mg or 1 g) of intravenous magnesium sulfate in neuropathic pain poorly responsive to strong opioid analgesics in patients with cancer.
Neuropathic pain may respond poorly to morphine and is often difficult to relieve. Recent attention has been drawn to the role of the N-methyl-D-aspartate (NMDA) receptor in the potentiation of neuropathic pain. Magnesium is known to block the NMDA receptor. ⋯ After receiving 1 g, one patient experienced complete relief and four experienced partial pain relief of similar duration; pain was unchanged in one patient. Intravenous magnesium sulfate in these doses appears to be safe and well tolerated. A useful analgesic effect may be obtained in some patients and further evaluation is warranted.
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Advances in basic and clinical research have greatly expanded the options for analgesic pharmacotherapy. There are three broad categories of analgesic medications: (1) nonopioid analgesics, which includes the nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, dipyrone, and others; (2) a diverse group of drugs known as the "adjuvant analgesics," which are defined as "drugs that have primary indications other than pain but may be analgesic in selected circumstances;" and (3) opioid analgesics. The advent of highly selective COX-2 inhibitors has generated excitement because of the possibility that these new NSAIDs will be much safer than previous COX inhibitors. ⋯ Pain specialists are now using opioids for chronic nonmalignant pain in addition to the traditional use for acute and cancer pain. This change in practice evolved from recognition that selected patients with chronic noncancer-related pain can experience sustained analgesia and function better with these drugs, without developing an addictive disorder. The combination of opioids and other drugs, such as an N-methyl-D-aspartate-receptor antagonist, may improve the balance between analgesia and adverse effects.
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J Pain Symptom Manage · Jan 2000
ReviewNMDA-receptor antagonists and opioid receptor interactions as related to analgesia and tolerance.
A model proposing that N-methyl-D-aspartate (NMDA) receptor and opioid receptor mechanisms overlap and interact within the same dorsal horn nociceptive neurons makes several predictions. First, hyperalgesia should be associated with opioid tolerance. ⋯ One is that, in addition to preventing tolerance and dependence, combining NMDA-receptor antagonists with both opioid and nonopioid analgesics may increase their analgesic potency. Preclinical animal studies demonstrate these advantages and underscore the practicality of the combined administration of nontoxic NMDA-receptor antagonists with various types of analgesic drugs.
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J Pain Symptom Manage · Jan 2000
MorphiDex (MS:DM) double-blind, multiple-dose studies in chronic pain patients.
Preclinical and double-blind single-dose placebo-controlled studies demonstrated that MorphiDex (MS:DM), a 1:1 ratio of morphine sulfate (MS) to dextromethorphan hydrobromide (DM), provides significantly greater analgesia than an equal dose of immediate release MS, with a faster onset, and a duration of > or = 8 h. The analgesic effect of MS:DM compared to MS was evaluated in 2 double-blind, multiple-dose studies in 321 patients with cancer and other chronic pain: a crossover study that consisted of two 2-wk periods and a 4-wk parallel study. As specified in the study protocols, patients took sufficient MS or MS:DM to achieve satisfactory pain control. ⋯ More patients preferred MS:DM to run-in MS than preferred MS to run-in MS (P = 0.026). The addition of DM to MS did not increase the incidence of adverse events, which were those commonly associated with opioid use. These studies confirm that MS:DM provides satisfactory pain relief but at a significantly lower morphine daily dose.