Sensitivity of repeated interdigital web pinching to detect antinociceptive effects of ibuprofen.
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AIMS: The aim of the current study was to assess the viability of the interdigital web pinch model as a test for analgesic activity in volunteer-based early phase drug development. METHODS: Pain thresholds and sensitization to a series of four sessions of interdigital web pinching (12 Newtons force) were measured in 26 male volunteers before and 1 and 3 h after oral dosing with ibuprofen (800 mg) or placebo to ibuprofen. Within each time point, the pain thresholds were measured by calculating the average visual analogue scores (VAS) for the first session of pinching (VAS-1). Sensitization to pinching was assessed by calculating the average changes in these scores for the three subsequent sessions of pinching (VAS-2). Moreover, the difference between the VAS score after the first session of pinching and that obtained at the end of the fourth session of pinching was calculated as a secondary endpoint (VAS-3). RESULTS: Treatment with ibuprofen had no significant effect on VAS-1 at either 1 or 3 h after dosing. However, the mean values of VAS-2 and VAS-3, were significantly reduced (P < 0.05) following treatment with ibuprofen. CONCLUSIONS: This model has been able to detect an antinociceptive effect with ibuprofen. However, large numbers of subjects were required in order to demonstrate this effect and this feature would restrict the model's utility in early phase clinical trials where small numbers of subjects are normally employed. (+info)
Chemoprevention of breast cancer in rats by celecoxib, a cyclooxygenase 2 inhibitor.
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Nonsteroidal anti-inflammatory drugs (NSAIDs) have been observed to reduce the relative risk of breast cancer. This prompted our investigation of the chemopreventive potential of celecoxib, a specific cyclooxygenase 2 blocker, against mammary carcinogenesis induced by 7,12-dimethyl-benz(a)anthracene in female Sprague Dawley rats. Treatment with celecoxib was examined and compared to treatment with the general NSAID, ibuprofen, and to a control group receiving only dimethylbenz(a)anthracene. Dietary administration of celecoxib (1500 ppm) produced striking reductions in the incidence, multiplicity, and volume of breast tumors relative to the control group (68%, 86%, and 81%, respectively; P < 0.001). Ibuprofen also produced significant effects, but of lesser magnitude (40%, 52%, and 57%, respectively; P < 0.001). These results help confirm the chemopreventive activity of NSAIDs against breast cancer and provide the first evidence that a cyclooxygenase 2 blocking agent, celecoxib, possesses strong chemopreventive activity against mammary carcinogenesis. (+info)
Dose-dependent effects of ketoprofen on the human gastric mucosa in comparison with ibuprofen.
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BACKGROUND: As non-steroidal anti-inflammatory drugs (NSAIDs) become available for over-the-counter use, it is important to define doses that would not cause undue gastroduodenal damage during the short periods for which self-medication with NSAIDs is licensed. AIM: To establish what dose of ketoprofen most closely resembles the maximum dose of ibuprofen (400 mg t.d.s.) licensed for self-medication. METHODS: We studied healthy volunteers in a double-blind double-dummy randomized crossover study. Each subject took, over four separate 10-day dosing periods, ibuprofen 400 mg t.d.s., ketoprofen 12.5 mg t.d.s., ketoprofen 25 mg t.d.s. or ketoprofen 50 mg t.d.s. Mucosal injury was assessed by endoscopy at baseline and on the 3rd and 10th day of each dosing period. Ex vivo gastric mucosal prostaglandin (PG) E2 evoked by vortex mixing was measured by radioimmunoassay. Serum thromboxane was also measured by radioimmunoassay. RESULTS: Ketoprofen 50 mg t.d.s. suppressed prostaglandin synthesis to a significantly greater extent than ibuprofen and caused significantly more gastroduodenal injury. The profile of prostaglandin synthesis and injury on ketoprofen 12.5 mg t.d.s. most closely resembled that of ibuprofen 400 mg t.d.s. CONCLUSIONS: Ketoprofen 12.5 mg t.d.s. is an appropriate dose for self-medication, which is likely to be similar to ibuprofen 400 mg t. d.s. in its effects on the stomach and duodenum. (+info)
Effects of furosemide on medullary oxygenation in younger and older subjects.
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Renal medullary hypoxia is characteristic of mammalian kidneys and can be assessed noninvasively in animals and humans by blood oxygen level-dependent magnetic resonance imaging (BOLD MRI). Water diuresis has been shown to improve medullary oxygenation in young human subjects but not in elderly subjects, a difference attributed to a decline in renal prostaglandin production with age. Loop diuretics such as furosemide also increase medullary oxygenation in experimental animals, by inhibiting active transport and oxygen consumption in the medullary thick ascending limb. We examined, using BOLD MRI, this response to furosemide in eight younger (23 to 34 years) and eight elderly (64 to 81 years) healthy women. We also attempted to assess the role of prostaglandins in age-related differences, using ibuprofen to inhibit prostaglandin E2 synthesis. Renal medullary oxygenation, initially low, increased during furosemide diuresis in younger subjects. In the older population, however, furosemide usually elicited little or no change in oxygenation of the renal medulla, despite profuse diuresis. Ibuprofen did not inhibit the action of furosemide to improve medullary pO2 in younger subjects. CONCLUSIONS: The action of loop diuretics to improve medullary oxygenation, apparent in younger subjects, is blunted by normal aging. Inhibition of prostaglandin synthesis did not counteract the effect of furosemide in younger subjects, suggesting that a decline in prostaglandin E2 production with age is not the central cause of this age-related defect. (+info)
Effect of subacute ibuprofen dosing on rectal mucosal prostaglandin E2 levels in healthy subjects with a history of resected polyps.
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Nonsteroidal antiinflammatory drugs are among the most promising chemopreventive agents for colorectal cancer. Although the mechanism by which nonsteroidal antiinflammatory drugs exert such effects remains to be further characterized, their best known pharmacological effect is inhibition of prostaglandin synthetase, which leads to decreases in tissue prostaglandin levels. We conducted a randomized, double-blind, controlled study to examine the effect of daily ibuprofen treatment on the rectal mucosal prostaglandin E2 (PGE2) levels in healthy subjects with a history of resected polyps. Study participants (n = 27) completed a 2-week run-in period and were then randomized to take a single, daily dose of ibuprofen (300 or 600 mg) or of a placebo for 4 weeks. Rectal biopsy specimens were taken before and after the run-in period and at 2 and 4 weeks after the ibuprofen/placebo treatment. Notably large between- and within-subject variability in the rectal mucosal PGE2 content was seen. The changes in PGE2 levels after ibuprofen/placebo treatment correlated with the baseline PGE2 content. After adjustment of the baseline values, 2 weeks of 300 mg/day of ibuprofen treatment resulted in significantly more suppression of PGE2 levels than that observed after the placebo treatment (55% versus 22% suppression from baseline; P = 0.033). Although other ibuprofen treatment schedules and doses appeared to result in suppression in the PGE2 levels, the suppression was not statistically significant because of the large variability in this measurement. Because lower doses are associated with fewer adverse effects, a dose of 300 mg of ibuprofen/day should be considered for future Phase II chemoprevention studies. Stratifying study participants, based on their baseline PGE2 levels and inclusion of a larger number of study subjects, are recommended for future trials where the rectal mucosal PGE2 level is to be used as a surrogate end point biomarker. (+info)
Effect of regulated expression of human cyclooxygenase isoforms on eicosanoid and isoeicosanoid production in inflammation.
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To examine the role of cyclooxygenase (COX) isozymes in prostaglandin formation and oxidant stress in inflammation, we administered to volunteer subjects placebo or bolus injections of lipopolysaccharide (LPS), which caused a dose-dependent increase in temperature, heart rate, and plasma cortisol. LPS caused also dose-dependent elevations in urinary excretion of 2,3-dinor 6-keto PGF(1alpha) (PGI-M) and 11-dehydro thromboxane B(2) (Tx-M). Platelet COX-1 inhibition by chronic administration of low-dose aspirin before LPS did not alter the symptomatic and febrile responses to LPS, but the increment in urinary PGI-M and Tx-M were both partially depressed. Pretreatment with ibuprofen, a nonspecific COX inhibitor, attenuated the febrile and systemic response to LPS and inhibited prostanoid biosynthesis. Both celecoxib, a selective COX-2 inhibitor, and ibuprofen attenuated the pyrexial, but not the chronotropic, response to LPS. Experimental endotoxemia caused differential expression of the COX isozymes in monocytes and polymorphonuclear leucocytes ex vivo. LPS also increased urinary iPF(2alpha)-III, iPF(2alpha)-VI, and 8,12-iso-iPF(2alpha)-VI, isoprostane (iP) indices of lipid peroxidation, and none of the drugs blunted this response. These studies indicate that (a) although COX-2 predominates, both COX isozymes are induced and contribute to the prostaglandin response to LPS in humans; (b) COX activation contributes undetectably to lipid peroxidation induced by LPS; and (c) COX-2, but not COX-1, contributes to the constitutional response to LPS in humans. (+info)
Rhinovirus-induced oxidative stress and interleukin-8 elaboration involves p47-phox but is independent of attachment to intercellular adhesion molecule-1 and viral replication.
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Virus-induced elaboration of proinflammatory cytokines is mediated by virus-induced oxidative stress. The purpose of these studies was to determine the source of the virus-induced oxidative stress. Inhibition of viral replication with antibody to intercellular adhesion molecule-1 had no effect on virus-induced oxidative stress or interleukin-8 (IL-8) response (597+/-88 vs. 668+/-78 pg/mL in control cells). Treatment of cells with diphenylene iodonium inhibited virus-induced oxidative stress and IL-8 elaboration, but allopurinol, ibuprofen, and rotenone had no effect. Studies in cell lines produced from a patient with gp91-phox deficiency revealed normal responses. In contrast, the oxidative response was decreased and the IL-8 concentration was 227+/-36 pg/mL in cells from a patient with p47-phox deficiency, compared with 664+/-48 pg/mL in control cells. These studies suggest that the stimulation of reactive oxygen species by viral challenge occurs at the cell surface even in the absence of viral replication and involves a flavoprotein that may act in concert with p47-phox. (+info)
PKA and arachidonic acid activation of human recombinant ClC-2 chloride channels.
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An HEK-293 cell line stably expressing the human recombinant ClC-2 Cl(-) channel was used in patch-clamp studies to study its regulation. The relative permeability P(x)/P(Cl) calculated from reversal potentials was I(-) > Cl(-) = NO(3)(-) = SCN(-)>/=Br(-). The absolute permeability calculated from conductance ratios was Cl(-) = Br(-) = NO(3)(-) >/= SCN(-) > I(-). The channel was activated by cAMP-dependent protein kinase (PKA), reduced extracellular pH, oleic acid (C:18 cisDelta9), elaidic acid (C:18 transDelta9), arachidonic acid (AA; C:20 cisDelta5,8,11,14), and by inhibitors of AA metabolism, 5,8,11,14-eicosatetraynoic acid (ETYA; C:20 transDelta5,8,11,14), alpha-methyl-4-(2-methylpropyl)benzeneacetic acid (ibuprofen), and 2-phenyl-1,2-benzisoselenazol-3-[2H]-one (PZ51, ebselen). ClC-2 Cl(-) channels were activated by a combination of forskolin plus IBMX and were inhibited by the cell-permeant myristoylated PKA inhibitor (mPKI). Channel activation by reduction of bath pH was increased by PKA and prevented by mPKI. AA activation of the ClC-2 Cl(-) channel was not inhibited by mPKI or staurosporine and was therefore independent of PKA or protein kinase C activation. (+info)