Concentrations Of Non-steroidal Anti-inflammatory Drugs Research Articles

Effects of non-steroidal anti-inflammatory drugs on cell proliferation and death in cultured epiphyseal-articular chondrocytes of fetal rats

Previous reports indicated that non-steroidal anti-inflammatory drugs (NSAIDs) suppress bone repair. Our previous study further found that ketorolac delayed the endochondral bone formation, and the critical effective timing was at the early stage of repair. Furthermore, we found that NSAIDs suppressed proliferation and induced cell death of cultured osteoblasts. In this study, we hypothesized that chondrocytic proliferation and death, which plays an important role at the early stage of endochondral bone formation, might be affected by NSAIDs. Non-selective NSAIDs, indomethacin, ketorolac, diclofenac and piroxicam; cyclooxygenase-2 (COX-2) selective NSAIDs, celecoxib and DFU (an analog of rofecoxib); prostaglandins (PGs), PGE1, PGE2 and PGF2α; and each NSAID plus each PG were tested. The effects of NSAIDs on proliferation, cell cycle kinetics, cytotoxicity and cell death of epiphyseal-articular chondrocytes of fetal rats were examined. The results showed that all the tested NSAIDs, except DFU, inhibited thymidine incorporation of chondrocytes at a concentration range (10 −8 to 10 −4 M) covering the theoretic therapeutic concentrations. Cell cycle was arrested by NSAIDs at the G 0/G 1 phase. Upon a 24 h treatment, LDH leakage and cell death (both apoptosis and necrosis) were significantly induced by the four non-selective NSAIDs in chondrocyte cultures. However, COX-2 inhibitors revealed non-significant effects on cytotoxicity of chondrocytes except higher concentration of celecoxib (10 −4 M). Replenishments of PGE1, PGE2 or PGF2α could not reverse the effects of NSAIDs on chondrocytic proliferation and cytotoxicity. In this study, we found that therapeutic concentrations of non-selective NSAIDs caused proliferation suppression and cell death of chondrocytes, suggesting these adverse effects may be one of the reasons that NSAIDs delay the endochondral ossification during bone repair found in previous studies. Furthermore, these effects of NSAIDs may act via PG-independent mechanisms. COX-2 selective NSAIDs showed less deleterious effects on chondrocytic proliferation and death.

Comparison of cyclooxygenase inhibitory activity and ocular anti-inflammatory effects of ketorolac tromethamine and bromfenac sodium

ABSTRACTObjective: To compare the cyclooxygenase (COX) activity and anti-inflammatory effects of the nonsteroidal anti-inflammatory drugs (NSAIDs) ketorolac tromethamine (ketorolac) and bromfenac sodium (bromfenac).Methods: Cyclooxygenase activity and selectivity was determined in vitro by measuring prostaglandin E2 (PGE2) production following incubation of varying concentrations of NSAID with human recombinant COX‐1 or COX‐2 and arachidonic acid. Anti-inflammatory effects were evaluated in a rabbit model in which an ocular inflammatory response was induced by intravenous injection of 10 µg/kg lipopolysaccharide (LPS). In study animals, one eye was treated with 50 µL (+/–) ketorolac 0.4% (Acular LS) or bromfenac 0.09% (Xibrom) and the other eye with 50 µL buffered saline. In control animals, both eyes were treated with vehicle. All animals were treated twice: 2 hours and 1 hour before LPS.‡ Acular LS is a trade name of Allergan Inc, Irvine, CA, USA§ Xibrom is a trade name of ISTA Pharmaceuticals, Irvine, CA, USAMain outcome measures: PGE2 production in vitro, measured by enzyme immunoassay; fluorescein isothiocyanate (FITC)-dextran leakage into the anterior chamber, measured by fluorophotometry; aqueous PGE2 levels in vivo, measured by ELISA immunoassay.Results: Ketorolac was six times more active against COX‐1 ( IC50 = 0.02 µM) than COX‐2 ( IC50 = 0.12 µM) while bromfenac was ≈ 32 times more active against COX‐2 ( IC50 = 0.0066 µM) than COX‐1 ( IC50 = 0.210 µM). In the animal model, both drugs resulted in nearly complete inhibition of FITC-dextran leakage and PGE2 production in the anterior chamber of treated eyes. There was also a 79% inhibition ( p < 0.001) of FITC-dextran leakage in the contralateral eyes of bromfenac-treated rabbits, and a 22.5% inhibition (not statistically significant) in the contralateral eyes of ketorolac-treated rabbits.Conclusions: Ketorolac is relatively COX‐1 selective while bromfenac is potently selective for COX‐2 over COX‐1. In the animal model, both ketorolac 0.4% and bromfenac 0.09% demonstrated maximal anti-inflammatory activity in treated eyes. Only bromfenac 0.09% had a significant effect on the contralateral eye, suggesting possible systemic absorption of this drug.

Effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs on the production of reactive oxygen species by activated rat neutrophils

The release of reactive oxygen specie (ROS) by activated neutrophil is involved in both the antimicrobial and deleterious effects in chronic inflammation. The objective of the present investigation was to determine the effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) on the production of ROS by stimulated rat neutrophils. Diclofenac (3.6 microM), indomethacin (12 microM), naproxen (160 microM), piroxicam (13 microM), and tenoxicam (30 microM) were incubated at 37 masculineC in PBS (10 mM), pH 7.4, for 30 min with rat neutrophils (1 x 10(6) cells/ml) stimulated by phorbol-12-myristate-13-acetate (100 nM). The ROS production was measured by luminol and lucigenin-dependent chemiluminescence. Except for naproxen, NSAIDs reduced ROS production: 58 +/- 2% diclofenac, 90 +/- 2% indomethacin, 33 +/- 3% piroxicam, and 45 +/- 6% tenoxicam (N = 6). For the lucigenin assay, naproxen, piroxicam and tenoxicam were ineffective. For indomethacin the inhibition was 52 +/- 5% and diclofenac showed amplification in the light emission of 181 +/- 60% (N = 6). Using the myeloperoxidase (MPO)/H2O2/luminol system, the effects of NSAIDs on MPO activity were also screened. We found that NSAIDs inhibited both the peroxidation and chlorinating activity of MPO as follows: diclofenac (36 +/- 10, 45 +/- 3%), indomethacin (97 +/- 2, 100 +/- 1%), naproxen (56 +/- 8, 76 +/- 3%), piroxicam (77 +/- 5, 99 +/- 1%), and tenoxicam (90 +/- 2, 100 +/- 1%), respectively (N = 3). These results show that therapeutic levels of NSAIDs are able to suppress the oxygen-dependent antimicrobial or oxidative functions of neutrophils by inhibiting the generation of hypochlorous acid.

Relationships Between the Concentrations of Prostaglandins and the Nonsteroidal Antiinflammatory Drugs Indomethacin, Diclofenac, and Ibuprofen

To study the concentration-effect relationships of the nonsteroidal antiinflammatory drugs (NSAIDs) indomethacin, diclofenac, and ibuprofen; to investigate whether standard doses of these drugs inhibit prostaglandin concentrations to a similar extent, determined by measuring the concentration of a surrogate marker of prostaglandin E 2 (PGE 2 ); and to determine the extent to which dose increases produce analogous increases in prostaglandin inhibition. Single-dose, randomized, crossover trial with a 1-week washout period. University biopharmaceutics and pharmacokinetics laboratory. Eight healthy adult volunteers younger than 35 years old. Subjects were administered two different standard doses of regular formulations (not enteric coated) of each NSAID on separate occasions. Plasma samples were collected for determination of drug and 13,14-dihydro-15-keto-PGE 2 (PGEM; the surrogate marker of PGE 2 ) concentrations at regular intervals after administration of each NSAID dose. Statistically significant linear correlations were found between the percent reduction in PGEM concentration and the concentrations of diclofenac, indomethacin, and ibuprofen in plasma (R 2 = 0.992-0.999). The PGEM plasma concentrations correlated inversely with NSAID plasma concentrations, indicating maximum inhibition when the highest NSAID plasma concentrations were achieved. Statistically significant differences in the percent inhibition of PGEM concentrations were observed between the two doses for each NSAID (p<0.05), but not between subjects for each NSAID. Doubling the dose (100% increase) of diclofenac and indomethacin produced a 60-65% increase in maximum inhibition of PGEM concentrations, whereas a 50% increase in dose produced a 44% increase in the maximum effect of ibuprofen. Prostaglandin inhibition, as measured by changes in PGEM concentrations, correlated significantly with NSAID concentrations in plasma and differed significantly between high and low NSAID doses. Measurement of PGEM plasma concentrations appears to be a promising marker for estimation of relative potency of NSAIDs.

Membrane permeabilization by non-steroidal anti-inflammatory drugs

The cytotoxicity of non-steroidal anti-inflammatory drugs (NSAIDs) is involved in the formation of NSAID-induced gastric lesions. The mechanism(s) behind these cytotoxic effects, however, is not well understood. We found here that several NSAIDs tested caused hemolysis when employed at concentrations similar to those that result in cytotoxicity. Moreover, these same NSAIDs were found to directly permeabilize the membranes of calcein-loaded liposomes. Given the similarity in NSAID concentrations for cytotoxic and membrane permeabilization effects, the cytotoxic action of these NSAIDs may be mediated through the permeabilization of biological membranes. Increase in the intracellular Ca2+ level can lead to cell death. We here found that all of NSAIDs tested increased the intracellular Ca2+ level at concentrations similar to those that result in cytotoxicity. Based on these results, we consider a possibility that membrane permeabilization by NSAIDs induces cell death through increase in the intracellular Ca2+ level.

MEK inhibition of pancreatic carcinoma cells by U0126 and its effect in combination with sulindac.

The MAP kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) pathway is critical for cell growth and survival. In the current study, we examined the effect of inhibiting the MEK-ERK pathway in pancreatic tumor cells with the MEK-specific inhibitor U0126. In addition, we investigated whether the MEK-ERK pathway influenced the response of pancreatic cancer cells to nonsteroidal antiinflammatory drugs (NSAIDs). Cell growth was monitored by a colorimetric proliferation assay and cell counts. Cell cycle analysis was performed using flow cytometry. Apoptosis was measured using a DNA fragmentation ELISA. Protein expression was detected by Western blot. Treatment with U0126 dose dependently inhibited the growth of 3 human pancreatic carcinoma cell lines (BxPC-3, PANC-1, and MIA PaCa-2). U0126 treatment resulted in cell-cycle alterations but did not induce apoptosis. Growth inhibitory concentrations of NSAIDs unexpectedly increased ERK phosphorylation in BxPC-3 and MIA PaCa-2 cells. We therefore evaluated the effect of treating pancreatic tumor cells with the combination of the NSAID sulindac and U0126. Treatment with U0126 complemented sulindac-induced growth inhibition in BxPC-3 and PANC-1 cells. The expression of several cell cycle (p21, p27, cyclin D1) and apoptotic (survivin, Bcl-xL) regulatory proteins was altered after U0126 and/or sulindac treatment. Our findings suggest that inhibition of the MEK-ERK signaling pathway may sensitize pancreatic tumor cells to NSAID therapy.

Effects of aspirin and indomethacin on endothelial cell proliferation in vitro.

Non-steroidal anti-inflammatory drugs (NSAID) are associated with delayed peptic ulcer healing. Ulcer healing is dependent on angiogenesis, which requires endothelial cell (EC) proliferation. The present study aimed to determine whether NSAID and prostaglandin E2 (PGE2) inhibited EC proliferation in vitro. Effects of 50 micro L aspirin (10 micro M-1 mM), indomethacin (10 micro M-1 mM) and PGE2 (1 micro M-0.1 mM) on the proliferation, viability and cell cycle of human dermal microvascular (HuDMEC) and human umbilical vein (HUVEC) EC were assessed using dual staining cell viability, 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide and flow cytometry assays. Proliferation of HuDMEC and HUVEC was significantly inhibited by 0.1 mM/1 mM indomethacin, 1 mM aspirin and 100 micro M PGE2, with a significant (P < 0.05) increase in EC necrosis with 1 mM indomethacin and 100 micro M PGE2. No effects on cell cycle were demonstrated. High concentrations of NSAID inhibit both HuDMEC and HUVEC proliferation in vitro by cytotoxic (indomethacin) or cytostatic (aspirin and indomethacin) mechanisms. Interestingly, PGE2 was also antiproliferative. Inhibition of EC proliferation may prevent angiogenesis at the ulcer site, which may in part explain the delayed ulcer healing associated with NSAID.

Effect of selective vs. non-selective cyclo-oxygenase inhibitors on fetal membrane prostaglandin synthesis

Increased expression of the inducible isoform of cyclo-oxygenase (COX-2) and prostaglandin output from fetal membranes is a key stage in human parturition. Prostaglandin production can be inhibited by non-steroidal anti-inflammatory drugs (NSAIDs), but these may also inhibit cyclo-oxygenase enzymes in fetal tissues, and hence cause potentially serious side effects. We have compared the concentrations of NSAIDs that inhibit maximal PGE2 synthesis from intact human fetal membrane explants in vitro with those found in human plasma after standard anti-inflammatory treatment. The concentrations of all six drugs that caused a 50% inhibition of fetal membrane prostaglandin output were lower than average plasma levels achieved during treatment. This effect was greatest for nimesulide and indomethacin, indicating that these drugs require further study at low doses in vivo, as this could achieve the same tocolytic effect with diminished adverse fetal effect. These drugs were also the most potent inhibitors of fetal membrane prostaglandin output, consistent with their effects on COX-2 activity.

Is inhibition of cyclooxygenase required for the anti-tumorigenic effects of nonsteroidal, anti-inflammatory drugs (NSAIDs)?: In vitro versus in vivo results and the relevance for the prevention and treatment of cancer

Active research is being conducted to unravel the cellular mechanisms mediating the anti-tumorigenic effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and their association with cyclooxygenase (COX) inhibition. The majority of NSAIDs inhibit either COX-1, COX-2, or both and exert their anti-COX, anti-inflammatory, and anti-tumorigenic effects in vivo in a parallel dose-dependent manner. The effects are seen at NSAID blood plasma concentrations of 0.1–5 μM. Significantly, the same compounds tested at the same concentrations in incubations with cultured tumor cells in vitro similarly inhibit COX activities but are devoid of anti-proliferative activity. Yet, at much higher concentrations (100–20,000 μM), these same NSAIDs do exert anti-proliferative effects in vitro due to apparent non-specific toxic effects, as evidenced by disruption of ion transport and mitochondrial oxidation in some cells. A small group of NSAIDs (e.g. sulindac) do not inhibit COX enzymes significantly but can reduce the synthesis of prostanoids by alternate mechanisms. One such mechanism is inhibition of agonist-stimulated phospholipase-mediated release of arachidonic acid from phospholipids leading to depressed synthesis of prostanoids, especially prostaglandin E 2 (PGE 2). Another group of non-COX inhibitors are the R-isomers of NSAIDs, based on the structure of 2-arylpropionic acid. These compounds exert anti-proliferative effects in vivo, acting by an as yet undetermined mechanism. A possible caveat in these data is an R to S chiral transformation in vivo that would render the R-isomer effect as being due to the S-isomer generated in vivo from it. Demonstration of minimal or no R to S inversion under the experimental in vivo conditions employed is, therefore, a necessary control in these studies. The overall body of data supports the conclusion that, for COX-inhibiting NSAIDs, their anti-tumorigenic effect in vivo is due to, and depends upon, inhibition of tumor COX enzymes, primarily COX-2. The cellular effects seen when adding high concentrations of NSAIDs to tumor cells cultured in vitro and the mechanisms proposed to mediate these effects may not have substantial relevance to the mechanisms that mediate the effects of NSAIDs in vivo.

Effects of Cyclooxygenase and Lipoxygenase Inhibitors on the Proliferation of Colon Cancer Cells and Their Production of Eicosanoids.

Epidemiological and laboratory studies suggest that nonsteroidal antiinflammatory drugs (NSAIDs) reduce the risk of colon cancer and that the inhibition of colon cancer is mediated through modulation of eicosanoid production. The present study examined the effect of cyclooxygenase (COX) and lipoxygenase (LOX) inhibitors on colon cancer cell growth and prostaglandin E(2) (PGE(2)) or leukotriene B(4) (LTB(4)) secretion by these cells. The human colon adenocarcinoma cell lines, Caco-2 and HT-29 cells, were cultured in serum-free medium with various concentrations of indomethacin, piroxicam or esculetin in the presence of 0.15nM or 10nM linoleic acid. Cell number was estimated by MTT assay and PGE(2) and LTB(4) were analyzed by enzyme immunoassay. The NSAIDs inhibited cell proliferation in a concentration-dependent manner. However, the potency and efficacy of each drug varied in the two cell lines. In Caco-2 cells, the effect of esculetin was higher than that of indomethacin, and piroxicam had no effect. In HT-29 cells, only indomethacin significantly inhibited cell proliferation. All three agents inhibited PGE(2) secretion in a dose-dependent manner; the effect of indomethacin was highest and that of esculetin lowest. The secretion of LTB4 was increased by indomethacin and piroxicam but decreased by esculetin. The effects of these drugs on cell proliferation and eicosanoid secretion were not influenced by linoleic acid concentrations in the culture media. Neither exogenous PGE2 nor LTB4 affected cell proliferation. The results of Pearson correlation analyses revealed that changes in cell proliferation were somewhat related to both concentrations of NSAIDs in the culture medium and production of PGE(2) and LTB(4). The present data suggests that the anti-proliferative effect of NSAIDs may not be entirely attributed to changes in the production of PGE2 and/or LTB4 in the two colon cancer cell lines. These NSAIDs may inhibit cell proliferation largely independent of their ability to modulate eicosanoid synthesis.

INHIBITION OF TENDON CELL PROLIFERATION AND MATRIX GLYCOSAMINOGLYCAN SYNTHESIS BY NON-STEROIDAL ANTI-INFLAMMATORY DRUGS IN VITRO

The purpose of this study was to investigate the effects of some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) on human tendon. Explants of human digital flexor and patella tendons were cultured in medium containing pharmacological concentrations of NSAIDs. Cell proliferation was measured by incorporation of 3H-thymidine and glycosaminoglycan synthesis was measured by incorporation of 35S-Sulphate. Diclofenac and aceclofenac had no significant effect either on tendon cell proliferation or glycosaminoglycan synthesis. Indomethacin and naproxen inhibited cell proliferation in patella tendons and inhibited glycosaminoglycan synthesis in both digital flexor and patella tendons. If applicable to the in vivo situation, these NSAIDs should be used with caution in the treatment of pain after tendon injury and surgery.

Effect of lipophilicity on in vivo iontophoretic delivery. I. NSAIDs.

The effect of drug lipophilicity on in vivo iontophoretic transdermal absorption was evaluated. Non-steroidal anti-inflammatory drugs (NSAIDs) were selected as model drugs with a wide range of lipophilicity: salicylic acid (SA), ketoprofen (KP), naproxen (NP) and indomethacin (IM). Cathodal iontophoresis of NSAIDs was conducted in rats (0.625 mA/cm2; 90 min), and drug concentrations in skin, cutaneous vein and systemic vein were determined. Skin concentrations of NSAID were higher in the case of lipophilic drugs (SA=KP=NP<IM), whereas cutaneous plasma concentrations decreased with an increase in lipophilicity (SA>KP=NP>IM). Additionally, the dependence of drug lipophilicity on systemic plasma concentration was similar to cutaneous plasma concentration. The transfer rate from skin to cutaneous vein (R(SC)) was calculated from the arterio-venous plasma concentration difference of drug in the skin. Normalized R(SC) by skin concentration (R(SC)/X(S)) yielded a negative correlation with the logarithm of n-octanol/buffer partition coefficient (Log P at pH 7.4), suggesting that transfer of NSAIDs from skin to cutaneous vein decreased with increasing lipophilicity (SA>KP=NP>IM). This correlation means that drug partitioning between stratum corneum and viable epidermis might be a dominant step.

Mechanism of action of acetaminophen: is there a cyclooxygenase 3?

Acetaminophen, also known as paracetamol, is a nonsteroidal anti-inflammatory drug with potent antipyretic and analgesic actions but with very weak anti-inflammatory activity. When administered to humans, it reduces levels of prostaglandin metabolites in urine but does not reduce synthesis of prostaglandins by blood platelets or by the stomach mucosa. Because acetaminophen is a weak inhibitor in vitro of both cyclooxygenase (COX)-1 and COX-2, the possibility exists that it inhibits a so far unidentified form of COX, perhaps COX-3. In animal studies, COX enzymes in homogenates of different tissues vary in sensitivity to the inhibitory action of acetaminophen. This may be evidence that there are >2 isoforms of the enzyme. Recently, a variant of COX-2 induced with high concentrations of nonsteroidal anti-inflammatory drugs was shown to be highly sensitive to inhibition by acetaminophen. Therefore COX-3 may be a product of the same gene that encodes COX-2, but have different molecular characteristics.

Inhibition of human liver phenol sulfotransferase by nonsteroidal anti-inflammatory drugs.

The aim of this investigation was to study the inhibition of 11 nonsteroidal anti-inflammatory drugs (NSAIDs) on the human liver phenol sulfotransferases (HL-PST) and catechol sulfotransferase (HL-CST). The activities of HL-PST and HL-CST were measured with 4 microM 4-nitrophenol and 60 microM dopamine (the sulfate acceptors) and 0.4 microM 3'-phosphoadenosine-5'-phosphosulfate [35S] (the sulfate donor). Samples of liver were obtained from five patients, aged 55-79 years, undergoing clinically indicated hepatectomy. The inhibition curves were constructed with at least five concentrations of the inhibitor. With the exception of piroxicam, NSAIDs inhibited HL-PST, and the estimates of the inhibitory concentration for 50% of responses (IC50; microM) were: 0.02 (mefenamic acid), 3.7 (diflunisal), 5.4 (nimesulide), 9.5 (diclofenac), 30 (salicylic acid), 41 (ketoprofen), 74 (indomethacin), 159 (ibuprofen), 245 (ketoralac) and 473 (naproxen). With 4-nitrophenol as the variable substrate, the inhibition of salicylic acid on HL-PST was non-competitive and the Ki and Kies were 18 microM and 21 microM (n = 5; P = 0.548), respectively. HL-CST was less susceptible than HL-PST to inhibition by NSAIDs, with only five drugs inhibiting this enzyme. The IC50 estimates for these drugs (microM) were 76 (mefenamic acid), 79 (diflunisal), 103 (indomethacin), 609 (salicylic acid) and 753 (diclofenac). The comparison of the IC50 estimates of HL-PST with the therapeutic plasma concentrations of NSAIDs corrected for the plasma unbound fraction was consistent with the view that mefenamic acid and salicylic acid, when administered at therapeutic doses, should impair the hepatic sulfation of those compounds that are substrates of phenol sulfotransferase.

Pharmacokinetics of nonsteroidal anti-inflammatory drugs in synovial fluid.

The major site of action for nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of rheumatic diseases is probably within the synovial compartment. There has been little work on the disposition of NSAIDs in the synovium and most studies have involved the measurement of their concentrations in synovial fluid. The concentrations of NSAIDs are more sustained in synovial fluid than in plasma, the difference being particularly noted with NSAIDs with short elimination half-lives. The more sustained concentrations may contribute to the prolonged effect of the short half-life NSAIDs, which are usually administered at intervals longer than their half-lives in plasma. The most widely used method of kinetic analysis of NSAIDs in synovial fluid is a compartmental model in which synovial fluid is a peripheral compartment of distribution of the drug. Repeated samples of synovial fluid from individual patients are difficult to collect, but even 1 sample of synovial fluid and plasma from each patient can provide useful data when analysed using the population approach to pharmacokinetic analysis. According to the compartmental model, the mean half-lives of efflux of the NSAIDs from synovial fluid range from 1.5 to 7 hours. The mean partition coefficient of most NSAIDs between synovial fluid and plasma is approximately 0.6. The NSAIDs are highly protein-bound, and the lower mean concentrations in synovial fluid are largely because of the lower concentrations of the binding protein, albumin. The NSAIDs diffuse into and out of synovial fluid in their unbound forms, but there is some diffusion in the protein-bound forms, particularly out of synovial fluid. The mean rates of diffusion of NSAIDs into and out of skin blisters in humans are similar to the rates of influx and efflux in the synovial fluid of the knee, but there is considerable variation between the pharmacokinetics of transfer at the 2 sites in individual patients. NSAIDs decrease the synthesis of prostaglandins in synovial fluid, but there are few data on the relationship between the kinetics of NSAIDs in synovial fluid and the effects on prostaglandin synthesis.

Adverse interactions between warfarin and nonsteroidal antiinflammatory drugs: mechanisms, clinical significance, and avoidance.

To review the mechanisms and clinical significance of adverse interactions between warfarin and nonsteroidal anti-inflammatory drugs (NSAIDs) and discuss how these interactions can be avoided. Previous studies of interactions between warfarin and NSAIDs or reports of adverse interactions were identified from a MEDLINE search (1976 to present) and from the reference lists of pertinent articles. All articles were considered for inclusion in the review. Pertinent information was selected for discussion. All NSAIDs can prolong bleeding time by inhibiting platelet function. High-dose aspirin has a direct hypoprothrombinemic effect. Phenylbutazone and its analogs enhance the hypoprothrombinemic effect of warfarin through a pharmacokinetic interaction by inhibiting the hepatic metabolism of warfarin. Mefenamic acid also enhances the anticoagulant effect of warfarin, but the mechanism is not known. The clinical relevance of protein binding displacement in the interaction between warfarin and NSAIDs has been overstated, although a significant one may be more likely in the presence of high concentrations of NSAIDs in patients with slow elimination of warfarin (e.g., those with severe heart failure or impaired liver function). NSAIDs can induce gastrointestinal bleeding, which is likely to be more severe if warfarin is also given. The combined use of warfarin and NSAIDs is generally discouraged because of the increased risk of bleeding in these patients. In patients receiving warfarin who also require NSAIDs, phenylbutazone and its analogs, high-dose aspirin, mefenamic acid, excessive use of topical methyl salicylate, and NSAIDs that are associated with a higher risk of bleeding peptic ulcers should be avoided. Patients should be closely monitored for anticoagulant control and bleeding complications during the combined use of warfarin and NSAIDs.

Human Plasma Protein Binding of the Angiotensin II Receptor Antagonist Losartan Potassium (DuP 753/MK 954) and Its Pharmacologically Active Metabolite EXP3174

The in vitro protein binding characteristics of the prototypical angiotensin II receptor antagonist losartan potassium (DuP 753/MK 954) and its pharmacologically active metabolite EXP3174 were determined by ultrafiltration with plasma from naive donors, volunteers dosed with losartan, and purified human plasma proteins. The binding of losartan was high, with a percent unbound (free) of 1.4 +/- 0.2% to 1.2 +/- 0.1% at concentrations ranging from 0.5 to 5.0 micrograms/mL; that is, approximately 98.6 to 98.8% bound. EXP3174 was more highly bound than losartan (P < .05) with 0.2 +/- 0.0% free at concentrations ranging from 0.1 to 10.0 micrograms/mL; or, greater than 99.7% bound. The binding in the plasma from volunteers given oral losartan was similar to that determined with plasma from naive donors, with 1.5 +/- 0.3 versus 1.4 +/- 0.1% free for losartan, and 0.5 +/- 0.1 versus 0.4 +/- 0.0% for EXP3174, respectively. This extensive plasma binding of both acidic compounds occurs primarily to albumin, with negligible binding to the alpha 1-acid glycoprotein. Although highly bound, neither losartan nor EXP3174 were displaced in vitro by pharmacologically relevant concentrations of non-steroidal antiinflammatory drugs (NSAIDs), warfarin, or diazepam; however, suprapharmacologic concentrations of the NSAIDs increased the free fraction of both compounds. These data show that the angiotensin II receptor antagonists losartan and EXP3174 are highly bound to plasma albumin in humans, although clinically significant drug interactions due to displacement from binding sites are unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Low concentrations of nonsteroidal anti-inflammatory drugs affect cell functions

The effect of 10 −14 − 10 −4M ibuprofen and aspirin both on arachidonic acid metabolism in peritoneal murine macrophages and on the concanavalin A-induced proliferation of murine splenocytes were investigated. It was shown that 10 −7 − 10 −4M ibuprofen inhibits the arachidonic acid metabolism. On the other hand, 10 −12 −10 −11M ibuprofen causes pronounced activation of arachidonic acid metabolism. The low concentration (10 −14 − 10 −10M) effects also take place when non-steroidal anti-inflammatory drugs influence other functions of the immune system: that is, they activate the splenocyte mitogen-induced proliferative response. These results are in accord with our suggestion that the low concentration effects of these drugs do not depend upon cell types and may have an important physiological significance.

Pharmacokinetic-pharmacodynamic drug interactions with nonsteroidal anti-inflammatory drugs.

The nonsteroidal anti-inflammatory drugs (NSAIDs) are very commonly prescribed, especially in the elderly population. In many countries more than 10 different NSAIDs are available. As the older pyrazole compounds like phenylbutazone, oxyphenbutazone and azapropazone are most prone to pharmacokinetic interactions, the use of these compounds should be avoided where possible. Acidic NSAIDs interact with bile acid-binding resins, resulting in decreased concentrations of NSAIDs in the blood. In earlier reports it was suggested that the absorption of NSAIDs was affected by antacids and sucralfate. More recently, it was shown that there is delayed absorption of these drugs, but there is no difference in the extent of absorption. Only salicylates had their urinary secretion enhanced by antacids, which increase the urinary pH to values > 7. Histamine H2-receptor antagonists can be combined safely with NSAIDs. The concomitant administration of probenecid increased the blood concentration of NSAIDs, so an enhanced anti-inflammatory effect can be expected when these 2 drugs are combined. More importantly, NSAIDs can cause pharmacokinetic drug-drug interactions with other drugs. As can be expected, interactions with drugs that have a small therapeutic window are most likely to be of clinical significance. For example, lithium, medium to high dose methotrexate and, to a lesser extent, cyclosporin may be affected by concomitant administration of an NSAID. Aspirin (acetylsalicylic acid) and/or pyrazoles interact with oral anticoagulants, oral antihyperglycaemic agents and the anticonvulsants phenytoin and valproic acid (sodium valproate). Elevation of blood concentrations of these agents can be potentially dangerous. Similarly, NSAIDs interact with digoxin. This interaction is most likely to occur in the elderly, in neonates or in patients with renal impairment. Indomethacin can influence the blood concentrations of aminoglycosides in neonates. Unfortunately, this effect seems unpredictable, so practical therapeutic recommendations cannot be made. When NSAIDs are combined with salicylates or diflunisal, the blood concentrations of the salicylate or diflunisal may increase. However, the clinical relevance of this increase in drug concentration seems to be of minor importance. Gastrointestinal bleeding caused by NSAIDs is the most dangerous when it results from a mixed pharmacokinetic/pharmacodynamic interaction; however, patients are also at risk when pharmacodynamic interactions only are involved.

Inhibition of histamine release from human FcεRI+ cells by nimesulide

We have previously demonstrated that pharmacological concentrations of non-steroidal anti-inflammatory drugs (NSAID) such as indomethacin, acetylsalicylic acid, and meclofenamic acid enhance IgE-mediated histamine release (HR) from human basophils. We have now examined the effects of nimesulide (NIM), a new NSAID, on mediator release from human basophils. Preincubation (10 min at 37°C) of basophils with pharmacological concentrations (10−6−10−3M) of NIM resulted in a concentration-dependent decrease of HR induced by anti-IgE, the Ca2+-ionophore A23187 and the formylated tripeptide f-Met-Leu-Phe (FMLP). Maximal inhibition of anti-IgE-induced HR was achieved after preincubation with 10−4M NIM and ranged between 14.5% and 44.5% (mean±SEM, 29.7±4.5%). The drug had a marked inhibitory effect on HR from basophils induced by A23187 (80.6±5.5%), FMLP (63.5±10.3%), 12-O-tetradecanoyl-phorbol-13-acetate (57.0±8.7%) and bryostatin 1 (65.7±7.6%). NIM also inhibited the IgE-mediated synthesis of peptide leukotriene C4 from basophils.