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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The recent discovery of an alternative form cyclooxygenase (cyclooxygenase-2, COX-2), which has been proposed to play a significant role in inflammatory conditions, may provide an opportunity to develop anti-inflammatory drugs with fewer side effects than existing non-steroidal anti-inflammatory drugs (NSAIDs). We have now identified 6-[(2,4-difluorophenyl)-thio]-5-methanesulfonamido-1-indanone++ + (20) (L-745,337) as a potent, selective, and orally active COX-2 inhibitor. The structure-activity relationships in this series have been extensively studied. Ortho- and para-substituted 6-phenyl substitutents are optimal for in vitro potency. Replacement of this phenyl ring by a variety of heterocycles gave compounds that were less active. The methanesulfonamido group seems to be the optimal group at the 5-position of the indanone system. Compound 20 has an efficacy profile that is superior or comparable to that of the nonselective COX inhibitor indomethacin in animal models of inflammation, pain, and fever and appears to be nonulcerogenic within the dosage ranges required for functional efficacy. Although 20 and its oxygen linkage analog 2 (flosulide) are equipotent in the in vitro assays, compound 20 is more potent in the rat paw edema assay, has a longer t1/2 in squirrel monkeys, and seems less ulcergenic than 2 in rats.
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PMID:Cyclooxygenase-2 inhibitors. Synthesis and pharmacological activities of 5-methanesulfonamido-1-indanone derivatives. 852 3

Understanding pain or, more precisely, the different types of pain, is above all a question of understanding its physiological mechanisms and, in this regard, the role of basic research has without doubt been to trigger the development of new therapeutic strategies. In an approach to these problems, the main international teams involved in pain research have attempted to develop models of experimental pain in rats. Clearly, research aimed at developing these models is controlled by certain ethical considerations; however, in this context, the end must surely justify the means. The main models used (acute or chronic inflammation, rheumatoid arthritis, peripheral neuropathy) certainly do not give a comprehensive representation of all the pain syndromes encountered in clinical practice, but they do provide new data concerning the physiological, behavioural and pharmacological aspects of pain. While giving a brief description of the complexity of the pain circuit, this article also makes reference to certain pharmacological approaches to the treatment of pain. Peripheral nociceptive messages are conveyed by a mosaic of unmyelinated free fibres distributed throughout cutaneous, muscular and articular tissue, and within the visceral walls. They are then transmitted via various nerve endings (polymodal nociceptors) by small diameter A delta and C fibres, which are activated by mechanical, thermal and chemical stimuli. It is nevertheless difficult to ascertain whether these small diameter fibres are involved only in nociception (specific nociceptors) or whether pain causes an excessive activation of these receptors, which under normal conditions have a role in the reflex that regulates various functions (nonspecific nociceptors). Numerous chemical substances play a part in generating nociceptive impulses (e.g. histamine, serotonin, prostaglandins). Furthermore, the role of neuropeptides, such as calcitonin gene-related peptide and particularly substance P, has been clearly demonstrated in the activation of early neurogenic inflammation. Other substances, such as bradykinin and cytokines, are involved in prolonging the sensation of pain. Nerve growth factor also prolongs the sensation of pain by increasing the cellular excitability of nociceptors and promoting the action of the sympathetic nervous system, which has a major role in controlling pain. The very great diversity of all these interacting substances makes the pharmacological treatment of pain extremely complex. Nevertheless, new therapeutic advances are providing interesting approaches, particularly the development of specific inhibitors of cyclo-oxygenase 2 (COX 2), which is produced by the inflammatory process. Such inhibitors would preserve COX 1, which is both constitutive and physiological, and thereby provide improved tolerability compared with currently used NSAIDs, which act upon both COX pathways. A major focus of research relating to new analgesics is the development of synthetic antagonists of bradykinin, substance P and N-methyl-D-aspartate receptors. An improved understanding of anatomical and electrophysiological processes has led to the discovery of new ascending pathways that transmit nociceptive messages to the reticular formation, the hypothalamus, and the amygdala, as well as to certain areas of the cortex. As a result the notion of one single pain centre is no longer valid. This idea is further reinforced by the knowledge that, at different stages of the pain pathway, different control systems constantly modulate the transmission of nociceptive information. Consequently, at a spinal level, activation of the large diameter cutaneous fibres (A alpha et beta) blocks pain stimuli transmitted by the small diameter fibres. Knowledge of this "gate control' mechanism of the posterior horn of the spinal cord is put to practical application in treatments involving transcutaneous electrical nerve stimulation. (ABSTRACT TRUNCATED)
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PMID:[The complexity of physiopharmacologic aspects of pain]. 919 Mar 19

PGs derived from cyclooxygenase-2 (COX-2), in particular PGE2, play important roles in the initiation of inflammation and pain. In the present study, we evaluated the role of COX-2-derived PGE2 in an animal model of established hyperalgesia. Inflammation and hyperalgesia were first induced by injection of carrageenan into rat footpads. Then we investigated the effects of subsequent therapeutic treatment with a selective COX inhibitor, with a nonsteroidal anti-inflammatory drug and with anti-PGE2 antibody. Test compounds were administered 1 to 3 hr after carrageenan challenge, and inhibition of pain (hyperalgesia, measured by withdrawal from a thermal stimulus), and changes in paw edema and PG levels were evaluated. The i.v. administration of a nonselective COX inhibitor, ketorolac, caused a rapid reduction in hyperalgesia in the inflamed footpad, returning it to near-normal values within 1 hr. Normal (control) paw response times were not affected. Therapeutic administration of ketorolac prevented most further swelling caused by carrageenan but did not reverse edema already present at the time of dosing. Administered p.o., a selective COX-2 inhibitor (SC-58635) was as efficacious as ketorolac in reducing inflammatory hyperalgesia. Footpad PG levels returned to base line or below within 5 min of dosing with ketorolac, which suggests rapid turnover of PG in the inflamed tissue. Therapeutic treatment with a monoclonal anti-PGE2 antibody also fully reversed the hyperalgesia response. These studies suggest that continuous production of PGE2 by the COX-2 enzyme is a critical element in sustaining the hyperalgesic response at sites of tissue inflammation.
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PMID:Inhibition of cyclooxygenase-2 rapidly reverses inflammatory hyperalgesia and prostaglandin E2 production. 939 78

Celecoxib (Celebrex) is the first of a new family of nonsteroidal anti-inflammatory drugs (NSAIDs) that selectively inhibit cyclooxygenase 2 (COX 2) while sparing COX 1. Clinical trials indicate that it is approximately as effective in relieving the pain of osteoarthritis and the pain and inflammation of rheumatoid arthritis as nonselective NSAIDs, but causes less gastrointestinal ulceration and bleeding. This paper reviews the pharmacology and possible clinical role of celecoxib and other COX 2-selective NSAIDs.
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PMID:COX 2-selective NSAIDs: biology, promises, and concerns. 1064 79

This electrophysiological study examined the effects of NSAID administration on synaptically-elicited responses of rat single spinal dorsal horn neurons to natural stimulation of peripheral receptive fields. Nociceptive responses consisted of a fast initial discharge during the stimulus followed by a slowly-decaying afterdischarge. The cyclooxygenase inhibitor, indomethacin (2.0-8.0 mg/kg, i.v.), was without effect on the on-going rate of discharge but dose-dependently inhibited synaptically-elicited responses to noxious cutaneous mechanical stimulation (fast initial discharge: n = 3/3 with 2 mg/kg, 5/8 with 4 mg/kg, 5/6 with 8 mg/kg; slowly-decaying afterdischarge: n = 3/3 with 2 mg/kg, 6/8 with 4 mg/kg, 6/6 with 8 mg/kg) and thermal (fast initial discharge: n = 7/9 with 8 mg/kg; slowly-decaying afterdischarge: n = 3/4 with 4 mg/kg, n = 7/9 with 8 mg/kg). The inhibitory effect of indomethacin started within 2-4 min and lasted up to 120 min. To eliminate any effect of indomethacin via cutaneous sensory receptors it was tested on the responses of some neurons to high intensity electrical stimulation of the sciatic nerve; indomethacin depressed these evoked responses (fast initial discharge: n = 5/6 with 2 mg/kg, n = 7/7 with 4 mg/kg; slowly-decaying afterdischarge: n = 6/6 with 2 mg/kg, n = 7/7 with 4 mg/kg). The brief excitatory responses to innocuous pressure (fast initial discharge: n = 2/3 with 2 mg/kg, n = 6/8 with 4 mg/kg, n = 4/6 with 8 mg/kg) and hair (n = 2/7 with 2 and 4 mg/kg, respectively) stimulation in both non-nociceptive and wide dynamic range neurons were also depressed but to a lesser extent. However, the prolonged excitation of three wide dynamic range neurons to continuous hair stimulation was almost entirely inhibited by indomethacin. Overall, inhibition of the afterdischarge and the excitatory effect of long-lasting synaptic input were greater than inhibition of the fast synaptic input-evoked initial discharge. The evidence supports the suggestion that systemically-administered indomethacin has an effect in the spinal cord and demonstrates an action specifically in the dorsal horn. The data are interpreted to suggest that sensory inputs are more involved than input-independent excitation of dorsal horn neurons in leading to de novo synthesis of eicosanoids and that the time course of this synthesis brings the levels to a point where COX inhibition can have an observable effect during prolonged excitation. Although the data suggest that COX inhibition differentially inhibits nociceptive versus non-nociceptive mechanisms at the cellular level, irrespective of the modality of the stimulus, this is the first direct demonstration that prolonged activation of synaptic mechanisms are preferentially inhibited. According to this it would be predictable that NSAIDs would be more effective on nociceptive types of pain characterized by time or prolonged inputs of primary afferents.
Pain 1999 Aug
PMID:NSAID-induced cyclooxygenase inhibition differentially depresses long-lasting versus brief synaptically-elicited responses of rat spinal dorsal horn neurons in vivo. 1046 22

The association of cytochrome c oxidase negative fibres (COX-negative) and ragged-red fibres (RR-fibres) with work related trapezius myalgia has been proposed. Hitherto studies have been small or without control groups. The aim of the present study was to investigate the prevalences of RR-fibres and COX-negative fibres in female cleaners with (n=25) and without (n=23) trapezius myalgia and in clinically healthy female teachers (n=21). The cleaners did mainly floor cleaning requiring monotonous loading on the trapezius muscle. A questionnaire covering background data and aspects of pain (prevalence, duration, intensity and influence on daily living) was answered. Biopsies were obtained from the trapezius muscle by an open surgical technique. The three groups did not differ in prevalence of COX-negative or COX-superpositive (i.e. type-I fibres with extremely strong brownish reaction in both the COX and SDH/COX stainings) fibres. The prevalence of COX-negative fibres was age dependent. Two subgroups of RR-fibres were present when stained for COX; COX-negative (73%) and COX-superpositive (26%) fibres. Forty-two percent of the COX-negative fibres were RR-fibres and 79% of the COX-superpositive were RR-fibres. A significantly (P=0.002) higher proportion of the COX-superpositive fibres in the cleaners were RR-fibres compared to the teachers. Multivariate regression analysis revealed that age, occupation as cleaner and a tender point in the trapezius were significantly associated with increased prevalences of RR-fibres; a cleaner with a tender point had a 4.35 higher prevalence of RR-fibres compared to a teacher without a tender point. No correlations between other pain related variables and prevalence of RR-fibres were noted. In conclusion, RR-fibres but not COX-negative or COX-superpositive fibres were correlated with cleaning work tasks and with a tender point in the trapezius.
Pain 2000 Feb
PMID:The prevalences of cytochrome c oxidase negative and superpositive fibres and ragged-red fibres in the trapezius muscle of female cleaners with and without myalgia and of female healthy controls. 1066 44

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.
J Pain Symptom Manage 2000 Jan
PMID:Current pharmacotherapy of chronic pain. 1068 34

The PSIs include acetaminophen, NSAIDs, and salicylates. They can be used alone for the treatment of mild pain or as an adjunct to opioid analgesia. In children, most experience is with acetaminophen and ibuprofen. For the treatment of mild to moderate pain, these agents can be administered as needed or at fixed intervals. The latter dosing scheme may provide a more consistent serum level, thereby improving analgesia. The major advantages of acetaminophen are its availability as a suppository for PR administration and its lack of effects on renal and GI function, adverse effects that may be seen with the NSAIDs. Many of the effects on platelet functioning, RBF, and the GI tract may be eliminated with the introduction of NSAIDs that selectively inhibit COX II without effects on COX I, the enzyme present in the GI tract, renal system, and platelets. Future evaluations with these agents in the pediatric population are needed. For more severe pain, the NSAID salicylate or acetaminophen can be combined with a weak opioid, such as codeine, oxycodone, or hydrocodone. When using oral analgesics, factors that may interfere with effective analgesia include a child's refusal to take the medication, ineffective doses and dosing regimens, decreased bioavailability following PO administration, inability to tolerate PO medications because of nausea or vomiting, altered GI motility, and a delayed onset caused by slow absorption. With such caveats in mind, the PO route provides an effective and cost-effective means for many patients. It should be considered as the primary route for pediatric patients in the treatment of mild to moderate pain, even in the hospital setting.
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PMID:Weak analgesics and nonsteroidal anti-inflammatory agents in the management of children with acute pain. 1083 89

The spinal activity of racemic ketoprofen and its enantiomers in models of neuropathic and tonic pain was explored in rats. Tactile allodynia and thermal hyperalgesia were induced by tight ligation of the L(5)/L(6) spinal nerves. Tonic pain was modeled by the formalin-induced flinch response. The spinal injection of (S)-ketoprofen alone or of morphine alone did not produce antiallodynic activity. A 1:1 combination of these drugs produced a robust dose-dependent antiallodynic action, consistent with previous observations where (S)-ketorolac combined with morphine also produced antiallodynia. (R)-ketoprofen given alone spinally produced a dose-dependent antiallodynia, but its activity was not augmented by spinal morphine. Conversely, (S)-ketoprofen, but not (R)-ketoprofen, blocked the second phase of the formalin-induced flinch response; neither enantiomer significantly blocked phase one of the formalin response. Again, (S)-, but not (R)-ketoprofen, interacted synergistically with spinal morphine in suppressing the phase II formalin response. These results are consistent with a spinal COX inhibitory action of (S)-ketoprofen. These results also point to a novel, as yet undefined, mechanism of action of (R)-ketoprofen against signs of neuropathic pain that does not appear to involve COX inhibition. The ability to modulate tactile allodynia is of special interest as this represents an aspect of clinical neuropathic pain that is very difficult to treat adequately.
Pain 2000 Aug
PMID:Differential effects of spinal (R)-ketoprofen and (S)-ketoprofen against signs of neuropathic pain and tonic nociception: evidence for a novel mechanism of action of (R)-ketoprofen against tactile allodynia. 1092 12

Postoperative pain, arising due to surgical tissue injury, is most frequent type of pain found in clinical practice. In postoperative analgesia opioids still constitute the fundamental form of pain treatment, but the development of neurophysiology and neuropharmacology has allowed for the optimization of postoperative analgesia. Therefore, in order to potentialize the pain relief effect of opioids and/or inhibit the nociception process and its consequences, diverse drugs and therapies are used. The procedure is called multimodal analgesia and consists in the administration of opioids in conjunction with NMDA antagonists, COX inhibitors, cholecystokinin antagonists, agonists of muscarine receptors, agonists of alpha-2 receptors or cytokine inhibitors. An alternative or supplementary therapy in the postoperative period relies on local anaesthetic techniques or TENS. There also exists pre-emptive analgesia, whose aim is to safeguard the central nervous system from increased afferent nociceptive stimulation during the operation.
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PMID:[Postoperative pain treatment]. 1096 35


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