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PubMed1995

Effect of anti-inflammatory drugs on myeloperoxidase-dependent hydroxyl radical generation by human neutrophils.

Neutrophils comprise a group of leukocytes that play a pivotal role in inflammation and vascular diseases like ischemia/reperfusion. These activated phagocytic cells are drawn to the site of injury, secreting superoxide and other oxidants derived from the formation of this free radical. This series of events frequently results in localized tissue damage. Surprisingly, free radical scavengers frequently offer only minimal relief. Why this is so may be due, in part, to our limited understanding of mechanisms that govern generation of free radicals in these settings. Although the metal ion-catalyzed Haber-Weiss reaction is considered the classical pathway for neutrophil-derived hydroxyl radical, an alternative mechanism, such as the myeloperoxidase-dependent pathway, may undoubtedly contribute to the formation of this free radical by stimulated neutrophils. In this study, we explored this possibility by investigating the role of different classes of anti-inflammatory drugs to ameliorate hydroxyl radical generation via the myeloperoxidase-dependent pathway. In this paper, we report that meclofenamic acid inhibited myeloperoxidase-dependent hydroxyl radical generation through scavenging of hypochlorous acid and not by direct inhibition of myeloperoxidase. The importance of these results with regard to the clinical efficacy of this anti-inflammatory compound remains to be determined as studies into the significance of myeloperoxidase-dependent hydroxyl radical formation in inflammatory tissue injury continue.

Anti-Inflammatory Agents↗
PubMed1985

Differential effect of prostaglandin synthetase inhibitor pretreatment on pentylenetetrazol-induced seizures in rat.

Release of prostaglandins (PGs) from brain tissue increases during experimentally-induced and spontaneous seizures. However, whether PGs or other arachidonic acid metabolites have a role in induction of seizures is still unclear. The effectiveness of pretreatment with PG synthetase inhibitors on pentylenetetrazol (PTZ)-induced models of epilepsy was investigated in free-moving rats with chronically-implanted supracortical electrodes. The effects on the electrocortical and motor manifestations of both a subconvulsive (30 mg.kg-1) and a convulsive (60 mg.kg-1) dose of PTZ were examined. Mefenamic acid (15 or 50 mg.kg-1), meclofenamic acid (15 or 50 mg.kg-1), ibuprofen (30 or 90 mg.kg-1) and paracetamol (300 or 450 mg.kg-1) delayed the onset of PTZ-induced convulsions. But mefenamic acid and meclofenamic acid also potentiated the excitatory effects of both subconvulsive and convulsive doses of PTZ. Indomethacin (3, 10 or 30 mg.kg-1) had no significant effect. The results suggest that the differential effects were produced by actions not related to the cyclo-oxygenase inhibition although the more consistent decrease of convulsive behavior may have resulted from inhibition of PG synthesis.

Acetaminophen↗
PubMed2001

[HPLC analysis of nonsteroidal antirheumatic substances in biological material. V. Fenamates].

The present paper surveys published HPLC methods estimating derivates of fenamic acid in biological materials and an HPLC method for estimation of meclofenamic acid in the samples of whole blood. Meclofenamic acid was isolated from the sample of the blood both liquid-liquid extraction and solid-liquid extraction. For determination of meclofenamic acid in the blood was preferred solid-liquid extraction. The adjust sample was analysed on reverse phase Separon SGX C-18 with the mobile phase methanol-water (pH 2.3) and detected at 220 nm. The method was used in a pharmacokinetic study of meclofenamic acid on rabbits.

Animals↗
PubMed1994

Changes in the endothelial cyclooxygenase pathway in resistance arteries of spontaneously hypertensive rats.

Vasodilator responses to adenosine and acetylcholine (ACh) were studied in ring preparations of mesenteric resistance arteries of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Adenosine (10(-7)-3 x 10(-4) M) caused relaxations in rings with endothelium. The relaxation was more pronounced in WKY than in SHR. Removal of the endothelium in WKY, but not in SHR, reduced the relaxation. In rings without endothelium, the relaxation was identical in the two strains. In WKY, the cyclooxygenase inhibitor meclofenamic acid attenuated the relaxation to adenosine in rings with endothelium but not in rings without endothelium. With meclofenamic acid, the relaxation was identical in WKY arteries with and without endothelium. ACh (10(-9)-10(-4) M) evoked endothelium-dependent relaxations in WKY. In contrast, in SHR the muscarinic agonist evoked contractions at higher concentrations (10(-6)-10(-4) M), whereas lower concentrations of ACh caused relaxations similar to those observed in WKY. The contraction in SHR was completely inhibited by meclofenamic acid, and with meclofenamic acid the relaxation to ACh was identical in WKY and SHR. Thus, adenosine evokes endothelium-dependent (through release of cyclooxygenase product) and endothelium-independent relaxations and ACh evokes endothelium-dependent relaxations in rat mesenteric resistance arteries. In SHR, the endothelium-dependent responses to the agonists are altered owing to the changes in the endothelial cyclooxygenase pathway.

Acetylcholine↗
PubMed1999

PGE2 induces its own secretion in vitro by bovine 270-day placenta but not by 200-day placenta.

Two separate experiments were conducted to determine whether prostaglandin (PG) E2 stimulates the secretion of progesterone by 270- or 200-day Brahman placentas in vitro. Secretion of progesterone, PGF2alpha, pregnancy specific protein B, or estradiol-17beta by 270-day Brahman placentas was not affected (p > or = 0.05) by PGE2, during the 4-h incubation period at the doses tested. Indomethacin or meclofenamic acid decreased (p < or = 0.05) 270-day Brahman placental secretion of PGE and PGF2alpha by 98 and 60%, respectively. However, PGE2 induced (p < or = 0.05) its own secretion, but not the secretion of PGF2alpha (p > or = 0.05), by 270-day Brahman placentas, even in the presence of indomethacin or meclofenamic acid at a dose of 100 ng/mL. Also, secretion of 8-Epi-PGE2 by Day 270 Brahman placentas was increased (p < or = 0.05) by PGE2. Secretion of progesterone, estradiol-17beta, or pregnancy specific protein B by 200-day Brahman placentas was not affected by PGE2, 8-Epi-PGE2, PGF2alpha, estradiol-17beta, or trichosanthin during the 4- or 8-h incubation period (p > or = 0.05). Secretion of estradiol-17beta at 8 h was lower (p < or = 0.05) in all treatment groups and did not differ (p > or = 0.05) among the 8-h incubation treatment groups. Secretion of PGE by 200-day Brahman placentas was reduced (p < 0.05) by indomethacin 72 and 82% and by meclofenamic acid 72 and 96%, respectively, at 4 and 8 h when compared to controls. Secretion of PGF2alpha was reduced (p < or = 0.05) 71 and 86% by indomethacin or 89 and 89% by meclofenamic acid at 4 and 8 h, respectively, and did not differ (p > or = 0.05) between 4 and 8 h of incubation. PGE2 did not (p > or = 0.05) induce secretion of PGE above what was added in any treatment group. PGE in culture media was increased (p < or = 0.05) by 8-Epi-PGE2, pregnancy specific protein B, and the 100 ng/mL PGF2alpha dose (p < or = 0.05), but not by PGE2, progesterone, estradiol-17beta, 8-Epi-PGF2alpha, or trichosanthin. Secretion of PGF2alpha by 200-day Brahman placentas was not affected (p > or = 0.05) by 8-Epi-PGE2, progesterone, or estradiol-17beta, but PGF2alpha secretion was increased (p < or = 0.05) by trichosanthin or PGE2, even in the presence of indomethacin or meclofenamic acid. It is concluded that PGE does not affect secretion of progesterone by 200- or 270-day bovine placentas, but, pregnancy specific protein B may regulate placental secretion of PGE. Also, indomethacin and meclofenamic may affect enzymes converting PGH to PGE rather than acting only on cyclooxygenase because indomethacin and meclofenamic acid lowered PGE secretion by 270-day Brahman placentas more than they lowered PGF2alpha. In addition, it is concluded that PGE2 can induce bovine placental secretion of PGE, but this is dependent upon the stage of gestation.

Abortifacient Agents, Nonsteroidal↗
PubMed1991

Pharmacology, pharmacokinetics, and therapeutic use of meclofenamate sodium.

Meclofenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) approved for use in arthritis (osteo and rheumatoid), analgesia (mild to moderate pain), dysmenorrhea, and heavy menstrual blood loss (menorrhagia). At least three different biochemical effects have been defined for meclofenamic acid. It is a potent inhibitor of the enzyme cyclooxygenase, thereby inhibiting the production of prostaglandins. It also inhibits the release of 5-HETE and LTB4 from human neutrophils stimulated with calcium ionophore and antagonizes the response of tissues to certain prostaglandins. These mechanisms may explain in part the pharmacological profile and clinical effectiveness of this compound. The rapid onset of activity of meclofenamic acid and its duration of action may be the result of its pharmacokinetic profile. Sodium meclofenamate is completely bioavailable from capsules relative to an oral suspension dosage form. Maximum meclofenamic acid plasma concentrations are achieved in 0.5-2 h following doses of capsules. Meclofenamic acid is extensively metabolized. One of the metabolites, metabolite 1, is approximately 20% as active as the parent compound in inhibiting cyclooxygenase activity in vitro. This metabolite accumulates in plasma during repeated dosing. It is possible that this metabolite may contribute to at least some of the activity observed following administration of sodium meclofenamate.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Roles of prostaglandins and nitric oxide in the effect of endothelin-1 on renal hemodynamics.

It is known that endothelin-1 stimulates the release of nitric oxide and prostaglandins in various vascular beds. We designed the present study to analyze the roles of prostaglandins and nitric oxide in the effect of endothelin-1 on the regulation of renal hemodynamics and renin release. We used N omega-nitro-L-arginine methyl ester (L-NAME) and meclofenamic acid to inhibit the production of nitric oxide and prostaglandins, respectively. With a nonfiltering kidney model, renal blood flow was reduced 21% in dogs treated with L-NAME and 18% in dogs treated with meclofenamic acid. Inhibition of nitric oxide and prostaglandins, however, produced opposite effects on estimated glomerular hydraulic pressure: L-NAME increased glomerular hydraulic pressure from 63.1 +/- 0.9 to 64.6 +/- 1.3 mm Hg (P < .01), and meclofenamic acid reduced glomerular hydraulic pressure from 63.3 +/- 1.4 to 59.8 +/- 1.6 mm Hg (P < .01). Endothelin-1 infusion produced a dose-dependent reduction in renal blood flow after blockade of nitric oxide and prostaglandins. The responses of glomerular hydraulic pressure were different in the two groups during endothelin-1 infusion. Endothelin-1 progressively reduced glomerular hydraulic pressure in a dose-dependent fashion in the meclofenamic acid group. However, endothelin-1 slightly increased glomerular hydraulic pressure until the infusion rate reached 5.0 ng/kg per minute. At that rate, endothelin-1 reduced glomerular hydraulic pressure from 63.3 +/- 1.4 to 47.0 +/- 1.4 mm Hg in the meclofenamic acid group (P < .01), a more than 25% reduction, whereas at the same dose, endothelin-1 reduced glomerular hydraulic pressure only less than 2% in the L-NAME group. In addition, blockade of nitric oxide and prostaglandins did not alter the inhibitory effect of endothelin-1 on renin release in the non-filtering kidney. Therefore, the present study demonstrates that the release of nitric oxide and prostaglandins might modulate the effects of endothelin-1 on the renal circulation. The present findings suggest that the differential vasoconstrictive effects of endothelin-1 on preglomerular and postglomerular vessels are associated with its stimulation of nitric oxide and prostaglandin production.

Animals↗
PubMed2006

Determination of fourteen non-steroidal anti-inflammatory drugs in animal serum and plasma by liquid chromatography/mass spectrometry.

The European Union has regulated the use of non-steroidal anti-inflammatory drugs (NSAIDs) in animal production and requires its member states to detect their residues in different matrices. In this work, a detailed MS and MS/MS study by ion-trap mass spectrometry of fourteen NSAIDs is described. Two multi-residue reversed-phase LC/ESI-MS/MS methods were developed, one for the determination of salicylic acid, naproxen, carprofen, flurbiprofen, ibuprofen, niflumic acid and meclofenamic acid in the negative ion mode, and the other for the determination of ketoprofen, suxibutazone, diclofenac, mefenamic acid, tolfenamic acid, phenylbutazone and its metabolite oxyphenbutazone in the positive ion mode. It was thus possible to confirm up to 14 different NSAID residues in serum and plasma samples of farmed animals, after chromatographic separation by a linear gradient. These substances were chosen as representative of different chemical subclasses of NSAIDs. The two methods were also validated in-house at three contamination levels, evaluating specificity and calculating mean recoveries, repeatability and within-laboratory reproducibility. The MS/MS product ion spectra were successfully used for the qualitative identification of all the drugs tested. All the NSAIDs, apart from salicylic acid, were recovered in high amounts, ranging between 71.6% and 100.9%.

Animals↗
PubMed1995

Reduction of intracellular pH by tenidap. Involvement of cellular anion transporters in the pH change.

Tenidap [5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H- indole-1-carboxamide], a novel antirheumatic agent, produces a rapid and sustained intracellular acidification when applied to cells in culture. To investigate the mechanism by which this change in ionic homeostasis is achieved, the acidification activities of structural analogs of tenidap were determined, and the movements of [14C]tenidap into and out of cells were explored. The acidification activity of tenidap was enhanced by lowering extracellular pH, suggesting that the free acid species was required for this process. Consistent with this requirement, a non-acidic analog of tenidap did not produce a change in intracellular pH (pHi). In contrast, multihalogenated derivatives of tenidap produced greater changes in pHi than did tenidap, and one analog produced a transient acidification from which the cell recovered; this recovery, however, was blocked by an inhibitor of the Na+/H+ antiporter. Fibroblasts incubated with [14C]tenidap achieved within 5 min a level of cell-associated drug that remained constant during longer incubations. Simultaneous addition of the electrogenic ionophore valinomycin or the P-glycoprotein inhibitor 4-(3,4-dihydro-6,7-dimethoxy-2(1H)-isoquinolinyl)-N-[2-(3,4-dimethoxyphe nyl) ethyl]-6,7-dimethoxy-2-quinazolinamine (CP-100,356) caused a time- and concentration-dependent increase in the level of cell-associated [14C]tenidap; other agents tested did not promote this enhanced cellular accumulation. [14C]Tenidap accumulated by fibroblasts in the presence of CP-100,356 subsequently was released when these cells were placed in a tenidap- and CP-100,356-free medium. Importantly, several agents that are known to inhibit anion transport processes, including alpha-cyano-beta-(1-phenylindol-3-yl) acrylate, 5-nitro-2(3-phenylpropylamino)-benzoic acid, and meclofenamic acid, inhibited efflux of [14C]tenidap. In contrast, ethacrynic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid did not impair the efflux process. Likewise, tenidap analogs that produced a sustained intracellular acidification blocked the efflux of [14C]tenidap, but non-acidifying species did not. These data suggest that movements of tenidap into and/or out of cells is a facilitated process subject to pharmacological intervention. Together, the structural selectivity of the acidification response and the evidence of facilitated transport suggest that the pHi modulating activity of tenidap is dependent on its unique physicochemical properties. Due to the dependence of these physicochemical properties on environmental and cellular conditions, in vivo expression of the acidification activity is likely to occur only within restricted environments that favor this tenidap-induced process.

Animals↗
PubMed1982

Augmentation of concanavalin A-induced immunosuppression by indomethacin.

These studies show that, in BALB/C mice, when antibody synthesis against sheep red blood cells is suppressed by concanavalin A, treatment with indomethacin (4-8 mg/kg per os) will augment this suppression. Two other nonsteroidal anti-inflammatory drugs, flufenamic acid and meclofenamic acid (50 mg/kg), also have this effect, whereas phenylbutazone was inactive at this dose. The augmentation of concanavalin A-induced immunosuppression by indomethacin could not be demonstrated on the response to the T-independent antigen polyvinypyrrolidone. In contrast to indomethacin, which inhibits cyclooxygenase, neither nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway, nor eicosa-5,8,11,14-tetraynoic acid, an inhibitor of both the cyclooxygenase and the lipoxygenase pathways, had this augmenting effect. Therefore, we do not have strong evidence that the absence of a prostaglandin is responsible for the effect of indomethacin. However, inhibition of the pathway leading to prostaglandin synthesis causes an increase in arachidonic acid metabolism via the lipoxygenase pathway. A product of this pathway, such as a leukotriene, may have immunosuppressive effects in this model. Evidence for the enhancement of a suppressor cell population is provided by an in vitro coculture assay. Cells treated with concanavalin A and indomethacin had more suppressive activity than cells treated with concanavalin A or indomethacin alone.

Animals↗
PubMed1983

Modification of sodium transport in freshwater mussels by prostaglandins, cyclic AMP and 5-hydroxytryptamine: effects of inhibitors of prostaglandin synthesis.

Pondwater acclimated unionid mussels, Ligumia subrostrata, experienced an increased Na influx, compared to controls, when injected with the phospholipase A2 inhibitor dexamethasone, or the cyclooxygenase inhibitors N-(2,6-dichloro-m-tolyl) anthranilic acid (meclofenamate) and indomethacin. Prostaglandin E2 (PGE2) or PGF2 alpha injections inhibited Na transport by depressing Na influx with no change in Na efflux. Prostaglandin E2 injections inhibited the indomethacin and dexamethasone dependent increase in Na transport. The PGE2 inhibition of Na influx was reversed by the administration of dibutyryl cAMP. Injections of serotonin (5-HT) elevated Na influx in mussels and the stimulation of Na transport by 5-HT could be potentiated by the injection of meclofenamate.

Animals↗
PubMed1998

Evaluation of selective inhibition of canine cyclooxygenase 1 and 2 by carprofen and other nonsteroidal anti-inflammatory drugs.

OBJECTIVE: To evaluate the activity of carprofen and other nonsteroidal anti-inflammatory drugs (NSAID) against isozymes of canine cyclooxygenases (COX1 and COX2). PROCEDURE: Constitutive COX1 was obtained from washed canine platelets, and COX2 was obtained from a canine macrophage-like cell line that was induced with endotoxin. Activity of carprofen and other NSAID against COX1 and COX2 was compared. Dose-response curves were plotted, and calculations were performed to identify concentrations that caused 50% inhibition (IC50 [microM]) for each isozyme. Ratio of the COX1-to-COX2 IC50 was used as a measure of isozyme selectivity. RESULTS: Of the compounds evaluated, carprofen had the greatest selectivity for COX2. Potency of carprofen for canine COX2 was more than 100-fold greater than for canine COX1. Inhibition of canine COX2 (IC50, 0.102 microM) for the racemic mixture of carprofen (S and R stereoisomers) was primarily attributable to the S enantiomer (IC50, 0.0371 microM), which was approximately 200-fold more potent than the R enantiomer (IC50, 5.97 microM). Nimesulide had the next highest selectivity for COX2 (38-fold), and tolfenamic acid and meclofenamic acid had 15-fold selectivity for COX2. The other compounds tested did not have substantial selectivity for canine COX2 or were more selective for canine COX1. CONCLUSIONS: Carprofen was found to be a potent inhibitor of canine COX2. Of the compounds tested, carprofen had the highest selectivity for canine COX2. CLINICAL RELEVANCE: The selectivity of carprofen for canine COX2 may be an important factor for its use in dogs.

Animals↗
PubMed2000

Biochemically based design of cyclooxygenase-2 (COX-2) inhibitors: facile conversion of nonsteroidal antiinflammatory drugs to potent and highly selective COX-2 inhibitors.

All nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the cyclooxygenase (COX) isozymes to different extents, which accounts for their anti-inflammatory and analgesic activities and their gastrointestinal side effects. We have exploited biochemical differences between the two COX enzymes to identify a strategy for converting carboxylate-containing NSAIDs into selective COX-2 inhibitors. Derivatization of the carboxylate moiety in moderately selective COX-1 inhibitors, such as 5,8,11,14-eicosatetraynoic acid (ETYA) and arylacetic and fenamic acid NSAIDs, exemplified by indomethacin and meclofenamic acid, respectively, generated potent and selective COX-2 inhibitors. In the indomethacin series, esters and primary and secondary amides are superior to tertiary amides as selective inhibitors. Only the amide derivatives of ETYA and meclofenamic acid inhibit COX-2; the esters are either inactive or nonselective. Inhibition kinetics reveal that indomethacin amides behave as slow, tight-binding inhibitors of COX-2 and that selectivity is a function of the time-dependent step. Site-directed mutagenesis of murine COX-2 indicates that the molecular basis for selectivity differs from the parent NSAIDs and from diarylheterocycles. Selectivity arises from novel interactions at the opening and at the apex of the substrate-binding site. Lead compounds in the present study are potent inhibitors of COX-2 activity in cultured inflammatory cells. Furthermore, indomethacin amides are orally active, nonulcerogenic, anti-inflammatory agents in an in vivo model of acute inflammation. Expansion of this approach can be envisioned for the modification of all carboxylic acid-containing NSAIDs into selective COX-2 inhibitors.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1971

Selective blockade of the vasodepressor response to prostaglandin F 2 in the anaesthetized rabbit.

1. The prostaglandin-blocking activity of meclofenamic acid, N-(2,6-dichloro-m-tolyl)anthranilic acid (CI-583), was analysed in the anaesthetized rabbit. PGF(2alpha), PGE(1) and isoprenaline were injected before and after meclofenamic acid infusion.2. Isoprenaline produced a fall in blood pressure, a reduction in oviduct motility and a reduction in uterine motility if the uterus showed marked spontaneous motility. PGF(2alpha) uniformly produced a fall in blood pressure and an increase in both uterine and oviduct contractility. PGE(1) produced a fall in blood pressure, a reduction in oviduct motility and no consistent effect on uterine motility.3. Meclofenamic acid selectively blocked the vasodepressor response to PGF(2alpha). The vasodepressor responses to PGE(1) and isoprenaline as well as the effects of all three agonists on uterine and oviduct contractility were not reduced by treatment with meclofenamic acid.4. Polyphloretin phosphate (PPP) administered to two rabbits in a cumulative dose of 94 mg/kg showed no significant blocking action on the vasodepressor or uterine and oviduct contractor responses to PGE(1) or PGF(2alpha) though this compound, like meclofenamic acid, has been reported to antagonize the actions of PGE(1) and PGF(2alpha) on isolated smooth muscle preparations.

Animals↗
PubMed1985

Stoichiometry and kinetics of the interaction of prostaglandin H synthase with anti-inflammatory agents.

We have examined the kinetics, stoichiometry, and chemical nature of the interaction of three anti-inflammatory agents (indomethacin, flurbiprofen, and meclofenamic acid) with pure ovine prostaglandin H synthase. The kinetics of the interaction with the synthase for each of the three agents, monitored by the decrease in cyclooxygenase activity, was consistent with the model proposed by Rome and Lands (Rome, L.H., and Lands, W.E.M. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 4863-4865): a rapid and reversible initial binding, followed by a first-order decay of the synthase-inhibitor complex. A relatively stable form of the cyclooxygenase, which had 4-10% of the initial activity, was the eventual product of this decay process. The dissociation constants evaluated for the initial binding were 1.7 +/- 1.5 microM for indomethacin, 0.2 +/- 0.1 microM for flurbiprofen, and 0.08 +/- 0.06 microM for meclofenamic acid. The values of the first order rate constants for the subsequent decay process were 14.9 +/- 11.3 min-1 for indomethacin, 3.4 +/- 0.7 min-1 for meclofenamic acid, and 16.6 +/- 6.2 min-1 for flurbiprofen. In repeated titrations of the cyclooxygenase with the three agents, 1.3 +/- 0.3 mol of indomethacin, 1.2 +/- 0.1 mol of meclofenamic acid, and 1.2 +/- 0.1 mol of S-(+)-flurbiprofen/mol of synthase dimer were found to result in maximal inhibition of the enzyme. Racemic flurbiprofen required 2.4 +/- 0.3 mol/mol synthase dimer for full effect, and the R-(-)-isomer was not inhibitory. Inhibition of the cyclooxygenase activity by these agents thus appears to result from a stereospecific binding to only one of the subunits of the synthase. Intact indomethacin could be recovered quantitatively after prolonged incubation (in stoichiometric quantities) with the synthase had resulted in maximal inhibition of the cyclooxygenase activity. The time-dependent effect of indomethacin on the cyclooxygenase is thus likely to involve a conformational change in the synthase rather than a covalent interaction.

Animals↗
PubMed1988

Human monocytes exposed to Biostim (RU 41740) alter lymphocyte mitogenesis: mechanisms of action.

The immunomodulatory agent RU 41740 (Biostim), which is derived from Klebsiella pneumoniae, may augment mitogenic responses of purified human blood lymphocytes. In non-purified preparations, however, responses may be sharply reduced due to the fact that Biostim induces monocytes to secrete immunosuppressive factors. This investigation has shown that both these biological activities can be exerted by a single, major glucoprotein fraction of Biostim termed F1. The Biostim-induced suppression of mitogen responses was not blocked by antibodies directed against IFN alpha or IFN gamma, thus speaking against IFN as being a mediator of suppression. Reduced suppression, however, was observed in the presence of drugs which inhibit arachidonic acid transformation. The cyclo-oxygenase inhibitors meclofenamic acid and indomethacin, which diminish biosynthesis of prostaglandins, could partially block the Biostim-induced suppression. Such an effect was not observed with 5,8,11-eicosatrynoic acid (ETI) which is an inhibitor of 12-lipoxygenase and leukotriene biosynthesis. Combinations of ETI and meclofenamic acid, however, were more potent than the latter tested separately. Another drug termed diclofenac Na, which apart from being an inhibitor of cyclo-oxygenase, rapidly clears cells of free arachidonic acid by binding to triglycerides, was found to be the most potent in preventing Biostim-induced suppression of mitogen responses. It is concluded that Biostim-exposed monocytes liberate increased amounts of immunosuppressive eicosanoids such as prostaglandins.

Adjuvants, Immunologic↗
PubMed2006

Second-order calibration of excitation-emission matrix fluorescence spectra for the determination of N-phenylanthranilic acid derivatives.

A spectrofluorimetric method has been developed for the quantitative determination of mefenamic, flufenamic, and meclofenamic acids in urine samples. The method is based on second-order data multivariate calibration (unfolded partial least squares (unfolded-PLS), multi-way PLS (N-PLS), parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD), and bilinear least squares (BLLS)). The analytes were extracted from the urine samples in chloroform prior to the determination. The chloroform extraction was optimized for each analyte, studying the agitation time and the extraction pH, and the optimum values were 10 minutes and pH 3.5, respectively. The concentration ranges in chloroform solution of each of the analytes, used to construct the calibration matrix, were selected in the ranges from 0.15 to 0.8 microg mL-1 for flufenamic and meclofenamic acids and from 0.25 to 3.0 microg mL-1 for mefenamic acid. The combination of chloroform extraction and second-order calibration methods, using the excitation-emission matrices (EEMs) of the three analytes as analytical signals, allowed their simultaneous determination in human urine samples, in the range of approximately 80 mg L-1 to 250 mg L-1, with satisfactory results for all the assayed methods. Improved results over unfolded-PLS and N-PLS were found with PARAFAC, SWATLD, and BLLS, methods that exploit the second-order advantage.

Anti-Inflammatory Agents, Non-Steroidal↗