Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Traditionally, the analgesic action of nonsteroidal anti-inflammatory drugs (NSAIDs) has been explained on the basis of their inhibition of the enzymes that synthesise prostaglandins. However, it is clear that NSAIDs exert their analgesic effect not only through peripheral inhibition of prostaglandin synthesis but also through a variety of other peripheral and central mechanisms. It is now known that there are 2 structurally distinct forms of the cyclo-oxygenase enzyme (COX-1 and COX-2). COX-1 is a constitutive member of normal cells and COX-2 is induced in inflammatory cells. Inhibition of COX-2 activity represent the most likely mechanism of action for NSAID-mediated analgesia, while the ratio of inhibition of COX-1 to COX-2 by NSAIDs should determine the likelihood of adverse effects. In addition, some NSAIDs inhibit the lipoxygenase pathway, which may itself result in the production of algogenic metabolites. Interference with G-protein-mediated signal transduction by NSAIDs may form the basis of an analgesic mechanism unrelated to inhibition of prostaglandin synthesis. These is increasing evidence that NSAIDs have a central mechanism of action that augments the peripheral mechanism. This effect may be the result of interference with the formation of prostaglandins within the CNS. Alternatively, the central action may be mediated by endogenous opioid peptides or blockade of the release of serotonin (5-hydroxytryptamine; 5-HT). A mechanism involving inhibition of excitatory amino acids of N-methyl-D-aspartate receptor activation has also been proposed.
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PMID:The mechanisms of action of NSAIDs in analgesia. 892 54

1. The responses of wide dynamic range spinal dorsal horn neurones to noxious mechanical stimulation of the ankle or knee joint were tested before and after spinal administration of the non-selective cyclooxygenase (COX) inhibitors, indomethacin and meclofenamic acid. Neither of these drugs altered the responses of these neurones to noxious mechanical stimulation. 2. Wind-up of a spinal nociceptive reflex evoked by electrical stimulation of the sural nerve at C-fibre strength was dose-dependently inhibited by intravenous administration of indomethacin, a non-selective COX inhibitor, and SC58125, a selective COX-2 inhibitor. Intrathecal administration of indomethacin also reduced the wind-up of this nociceptive reflex. 3. Western blot analysis of proteins extracted from normal rat spinal cord revealed the presence of both cyclo-oxygenase (COX)-1 and COX-2 proteins. 4. Immunocytochemistry of sections of normal rat spinal cord with specific COX-1 antiserum revealed little specific COX-1-like immunoreactivity in the grey matter. With the same antiserum, intense COX-1-like immunoreactivity was observed in the cytoplasm, nuclear membrane and axonal processes of small to medium sized (< 1000 microns2) dorsal root ganglion (DRG) cell bodies. 5. Immunocytochemistry of sections of normal rat spinal cord incubated with specific COX-2 antiserum showed intense COX-2-like immunoreactivity (COX-2-li) in the superficial dorsal horn of the spinal cord (laminae I and II) and around the central canal (lamina X). COX-2-li was also observed in some neurones in deep dorsal horn and in individual motor neurones in ventral horn. COX-2-li was not observed in the cell bodies of DRG. 6. Superfusion of the lumbar spinal cord of normal rats with artificial CSF and subsequent radioimmunoassay revealed the presence of prostaglandin D2 (PGD2) < PGE2, but not PGI2 (determined by measurement of the stable metabolite, 6-keto-PGF1 alpha) or PGF2 alpha. 7. These data suggest that eicosanoids synthesized by an active COX pathway in the spinal cord of normal animals may contribute to nociceptive processing, but only when the spinal cord neurones are rendered hyperexcitable following C-fibre stimulation. Selective inhibition of one or both of the COX isoforms in normal animals may represent a novel target for spinal analgesia.
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PMID:Prostanoids synthesized by cyclo-oxygenase isoforms in rat spinal cord and their contribution to the development of neuronal hyperexcitability. 942 3

Two enzymes, cyclo-oxygenase (COX) and 5-lipoxygenase, act upon arachidonic acids to produce prostaglandins and leukotrienes. Inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) lowers synthesis of proinflammatory prostaglandins and produces analgesia. COX-2 is highly inducible by endotoxin, IL-1, hypoxia, epidermal growth factor (EGF), benzo[a]pyrene, and transforming growth factor beta 1(TGF-beta 1). COX-1 in constitutively expressed. Conventional NSAIDs also inhibit the synthesis of cytoprotective prostaglandins by COX-1 in the gastrointestinal tract. Surplus arachidonic acids accumulate and enhance the generation of leukotrienes via the lipoxygenase pathway inducing neutrophil adhesion to endothelium and vasoconstriction. The NSAIDs harboring a carboxyl group also inhibit oxidative phosphorylation (OXPHOS) lowering adenosine-triphosphate (ATP) generation leading to loss of mucosal cell tight junctions and increased mucosal permeability. Administration of NSAIDs that do not interfere with OXPHOS, and concomitant use of prostaglandin analogues to restore cytoprotection reduces complications of NSAID use. However, no NSAID that lacks potential for serious gastrointestinal toxicity is currently available. Selective inhibitors of COX-2 and 5-lipoxygenase are newer, promising drugs. Surprisingly, COX-2 null mice are able to mount an inflammatory response, suffering however, from kidney dysfunction and a shortened life span. Results of clinical studies on the long-term use of NSAID drugs such as selective inhibitors are still pending.
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PMID:Adverse effects of nonsteroidal anti-inflammatory drugs on the gastrointestinal system. 955 45

The new class of antiinflammatory and analgesic drugs, the selective cyclooxygenase (COX-2) inhibitors, which promise to be devoid of the types of toxicity associated with nonsteroidal antiinflammatory drugs (NSAID), especially adverse gastrointestinal effects, are under clinical trial but are not yet available for use. All NSAID, including those most recently introduced, exhibit nonselectivity of action, producing therapeutic blood levels that inhibit constitutive COX-1 and deplete tissue protective prostaglandins. Among NSAID, the diclofenac/misoprostol combination (Arthrotec) is unique in possessing an active component, misoprostol, to help prevent NSAID induced gastrointestinal damage. Ulcer damage and associated serious complications probably represent only the tip of the iceberg in relation to clinically significant side effects associated with the use of NSAID. In this context, metaanalysis of 8 large multicenter studies reported here has shown that patients taking NSAID show a mean decrease in hemoglobin over 4 - 12 weeks' assessment, with some 10-20% of patients exhibiting clinically significant decreases (> or = 1 g/dl) early in treatment. Patients taking diclofenac/misoprostol showed significantly less of a decline in hemoglobin and up to 50% fewer clinically significant decreases than patients receiving diclofenac alone. The misoprostol component of diclofenac/misoprostol may also help to restore homeostasis in tissues other than the gut. Inhibition of the activity or release of various tissue damaging agents and inflammatory cytokines, e.g., thromboxane and interleukin 1, are described, as are in vivo animal studies that have revealed synergistic or potentiating analgesic and antiinflammatory activities between misoprostol and NSAID, particularly diclofenac. Clinical studies in postsurgical dental pain in more than 500 patients have now shown enhanced analgesia, with greater relief over a longer period, for the diclofenac/misoprostol combination compared with diclofenac alone. The relevance of these findings to pain and inflammation control in arthritis is discussed. Enhanced control of morning stiffness provided by diclofenac/misoprostol, possibly also the result of misoprostol/diclofenac synergy, is also reported, and the development of an objective system that measures 24 hour ambulatory activity is described. Using this Numact recorder, improved mobility in patients receiving diclofenac 75 mg/misoprostol 200 microg was observed compared with patients treated with diclofenac 75 mg slow release. Further studies are being performed employing magnetic resonance imaging both to assess antiinflammatory effects in joint soft tissue architecture and to assess whether the synergistic stimulatory effects of diclofenac and misoprostol on human osteoarthritic cartilage that have been reported in vitro are clinically evident. A growing body of evidence supports the view that the diclofenac/misoprostol combination provides an improved therapeutic ratio over diclofenac alone, not only by improving gastrointestinal safety but also by enhancing analgesic/antiinflammatory effects.
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PMID:Diclofenac/misoprostol: novel findings and their clinical potential. 959 52

Explants of tissue derived from the medial collateral ligament (MCL) of normal and pregnant NZW rabbits cultured in the presence of substance P (SP), calcitonin gene-related peptide (CGRP), or both neuropeptides were found to have altered mRNA levels for a number of relevant molecules. Using a very efficient RNA isolation method, semi-quantitative RT-PCR and rabbit-specific primers, mRNA for growth factors (TGFbeta, bFGF, IGF-2, ET-1), cytokines (IL-1, TNF), enzymes (COX-2, iNOS), metalloproteinases (collagenase, stromelysin) and metalloproteinase inhibitors (TIMP-1, TIMP-2) were assessed after culture with or without neuropeptide. The results indicate that SP was effective in lowering mRNA levels for all of the molecules assessed in RNA from normal ligaments except IL-1beta, IGF-2 and TIMP-1, for which there was no significant effect. Similarly, CGRP was effective in lowering mRNA levels for all molecules except TNF, ET-1 and the TIMPs. The extent of the lowering of mRNA levels was both molecule-specific and neuropeptide-specific. When the experiments were repeated with ligament tissue from pregnant animals, a very different pattern of responsiveness to the neuropeptides was observed. While mRNA levels for 9/12 genes assessed were significantly affected by SP when normal MCL tissue was investigated, pregnancy abolished all significant responsiveness to this neuropeptide except for iNOS mRNA levels. In the case of iNOS mRNA, SP induced an increase in the steady-state levels, the opposite to what was observed with tissue from non-pregnant animals. For CGRP and SP+CGRP, tissue from pregnant animals was still responsive, but the pattern of responsiveness was changed from strictly a lowering of steady-state mRNA levels to elevations in mRNA levels for a number of genes. These findings indicate that mRNA levels for a number of genes can be influenced by neuropeptides known to be in ligaments. Thus, neuropeptides likely are important regulators of ligament cell metabolism. As the responsiveness to SP was nearly completely abolished during pregnancy, neuroregulatory influences mediated by this peptide are altered in the pregnant female. This loss of responsiveness to SP may also be one aspect of the analgesia associated with pregnancy.
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PMID:Pregnancy alters the in vitro responsiveness of the rabbit medial collateral ligament to neuropeptides: effect on mRNA levels for growth factors, cytokines, iNOS, COX-2, metalloproteinases and TIMPs. 978 99

Nimesulide is a newer non-steroidal anti-inflammatory drug (NSAID) with selective cyclo-oxygenase (COX)-2 blocking property and has demonstrated a potent analgesic and anti-inflammatory activity on oral and rectal administration. However, the Cmax through both these routes is reached only after 3 h of administration. Dose-dependent gastrointestinal side effects also limit the concentration of drug that can be achieved at the site of inflammation when administered through these routes. The present study was conducted to evaluate the antinociception induced by a new gel formulation of nimesulide when applied on the skin. Efficacy of topical nimesulide gel 1% (w/w) was studied on mice in the acetic-acid-induced writhing, tail flick latency (TFL) test and formalin-induced pain models. The antinociceptive effect of nimesulide was compared to diclofenac gel (1% w/w). Both the drugs induced dose-dependent analgesia with peak effect seen between 90 and 120 min after treatment. Greater antinociceptive effect (expressed as percent maximum possible effect) was seen in the writhing test than in the TFL test, indicating the peripheral action of both drugs. Nimesulide evidenced significant protection in the first phase of formalin-induced pain indicating modulation of peripheral nociceptors unlike other conventional NSAIDs. This suggests that COX-2 may be a primary contributor to afferent evoked increase in prostanoid-mediated changes in pain processing. Antinociception seen following drug application on the skin was lower than that seen on intraperitoneal administration, indicating localised action following topical application. The findings of the present study suggest that the transgel formulation of nimesulide provides significant analgesic activity when applied topically.
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PMID:Comparative analgesic efficacy of nimesulide and diclofenac gels after topical application on the skin. 988 12

Previous data have suggested that rofecoxib, a cyclooxygenase (COX)-2-specific inhibitor, had analgesic effects similar to those of the nonsteroidal anti-inflammatory drugs when tested in the post-dental surgery pain model. The objective of this parallel-group, double-masked, randomized, placebo- and active comparator-controlled clinical trial was to assess more fully the analgesic efficacy of rofecoxib in the treatment of postoperative dental pain. After dental surgery, 151 patients (50.3% women; mean age, 18.3 years; 93.4% white) experiencing moderate-to-severe pain were to receive a single dose of placebo, rofecoxib 50 mg, or ibuprofen 400 mg. Analgesic efficacy was assessed for up to 24 hours postdose using self-administered questionnaires. Tolerability was assessed using spontaneous reports of adverse experiences, physical findings, and laboratory measurements. The results of this study demonstrated that rofecoxib 50 mg was more effective than placebo on all measures of analgesic efficacy. Rofecoxib 50 mg exhibited overall analgesic effects, onset of analgesia, and peak analgesic effects that were not significantly different from those of ibuprofen 400 mg, with a significantly longer duration of action (P < 0.05). We concluded that rofecoxib was efficacious in the treatment of postoperative dental pain and that COX-2-derived prostanoids play a role in treatment of the pain associated with dental surgery.
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PMID:Analgesic efficacy of the cyclooxygenase-2-specific inhibitor rofecoxib in post-dental surgery pain: a randomized, controlled trial. 1044 Jun 19

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs and their widespread use is associated with increased gastro-intestinal toxic effects such as ulceration, haemorrhage, perforation and death. They result in these complications mainly by reducing cytoprotective prostaglandins (PGE2 and PGI2) in the stomach, through the inhibition of cyclo-oxygenase (COX) enzyme. The increased morbidity and mortality, in addition to enormous cost, associated with NSAID-associated side effects, necessitates a need for safer GI-friendly NSAID. Various approaches have been used to counteract NSAID associated side effects with varying degrees of success and acceptance. These include the use of alternative analgesia, anti-acid secretory agents like proton pump inhibitors, sucralfate and prostaglandin analogues. In addition, new types of NSAIDs are being developed, based on new understanding of their mechanism of action and the pathogenesis of inflammation. These include a new class of NSAIDs called "selective Cox-2 inhibitors". These agents preserve the COX-1 that is responsible for the production of cytoprotective prostaglandins in the stomach and selectively inhibit COX-2 induced at the sites of inflammation. Selective COX-2 inhibitors exert the same analgesic and anti-inflammatory effects as the existing NSAIDs but may be less toxic to the stomach. In this review the background development and well-structured clinical trials on this new generation NSAIDs are discussed.
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PMID:Non-steroidal anti-inflammatory drugs (NSAIDs) and gastro-intestinal toxicity: current issues. 1062 61

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. However, the cost-benefit of using these relatively more expensive drugs versus other NSAIDs plus gastro-protective therapies needs to be determined. Adjuvant analgesics can be grouped into four major classes according to their use: multipurpose, neuropathic pain, musculoskeletal pain, and cancer pain. There has been a dramatic increase in the number of these drugs during the past two decades and they now play an important role in the management of chronic pain. 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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PMID:Current pharmacotherapy of chronic pain. 1068 34

Even at the beginning of the next millennium, aspirin will still offer surprises. Its relatively young pharmacological history compares with the early use of salicylate-containing plants since antiquity. The Assyrians and the Egyptians were aware of the analgesic effects of a decoction of myrtle or willow leaves for joint pains. Hippocrates recommended chewing willow leaves for analgesia in childbirth and the Reverend Edward Stones is acknowledged as the first person to scientifically define the beneficial antipyretic effects of willow bark. At the beginning of the 19th century salicin was extracted from willow bark and purified. Although a French chemist, Charles Gerhardt, was the first to synthesize aspirin in a crude form, the compound was ignored, and later studied by Felix Hoffmann. He reportedly tested the rediscovered agent on himself and on his father, who suffered from chronic arthritis--a legend was born and Bayer Laboratories rose to the heights of the pharmacological world. First used for its potent analgesic, antipyretic and anti-inflammatory properties, aspirin was successfully used as an antithrombotic agent. Sir John Vane elucidated aspirin's active mechanism as an inhibitor of prostaglandin synthetase and received the Nobel Price in Medicine for this work in 1982. Two isoform of cyclooxygenase (COX-1 and COX-2) have now been identified, each possessing similar activities, but differing in characteristic tissue expression. The cox enzyme is now a target of drug interventions against the inflammatory process. After two centuries of evaluation, aspirin remains topical, and new therapeutic indications are increasingly being studied.
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PMID:[Aspirin throughout the ages: a historical review]. 1076


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