Properties Of Non-steroidal Anti-inflammatory Drugs Research Articles

Abstract LB-172: MicroRNAs mediate the inhibition of tumor cell invasion by sulindac

Abstract A large body of evidence indicates that nonsteroidal anti-inflammatory drugs (NSAIDs) have strong antineoplastic properties against a broad range of cancer types in early or late stage animal models of tumorigenesis. However, their use in humans for chemoprevention is limited by toxicities resulting from cyclooxygenase (COX) inhibition and the suppression of physiologically important prostaglandins. The anticancer properties of NSAIDs are generally attributed to the suppression of tumor cell proliferation and induction of apoptosis by inhibiting cyclooxygenase (COX), although numerous studies suggest that a COX-independent mechanism may either contribute to or be fully responsible for their activity. The effect of NSAIDs on tumor cell motility and invasion has not been well studied, despite clinical studies showing that certain NSAIDs can significantly increase the survival of patients with metastatic disease. Our results show that the NSAID, sulindac sulfide (SS) can potently inhibit the motility of human breast (MDA-MB-231 and SUM1315) and colorectal (HCT116 and HT29) tumor cells by a mechanism that is distinct from its tumor cell growth and COX inhibitory activity. To study the molecular basis for this activity, we investigated the involvement of microRNA (miRNA). A total of 132 miRNAs were found to be altered in response to SS treatment including miR-10b, miR-17, miR-21, and miR-9, which have been previously implicated in tumor invasion and metastasis. We confirmed that these miRNAs can stimulate tumor cell invasion and show that SS can attenuate their invasive effects (individual and cooperative) by down-regulating their expression. Employing luciferase and chromatin immunoprecipitation (ChIP) assays, NF-κB was found to bind the promoters of all four miRNAs to regulate their expression at the transcriptional level. Results from the immunofluorescence and Western Blotting assays show that SS can inhibit the translocation of NF-κB to the nucleus by decreasing the phosphorylation of IKKβ and IκB, which leads to down-regulation of these miRNAs. Analysis of the promoter sequences of the miRNAs suppressed by SS revealed that 81 of 115 sequences contained NF-κB binding sites. Our results demonstrate that SS can inhibit tumor cell invasion by suppressing NF-κB mediated transcription of miRNAs, which illustrate the mechanistic basis of this novel anticancer property of sulindac on tumor progression and metastasis. We expect these results are capable of supporting future clinical trials of sulindac in patients with metastatic disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-172. doi:1538-7445.AM2012-LB-172

The Search for a Chemoprevention Agent Effective against Melanoma: Considerations and Challenges

Studies examining the potential chemopreventive properties of nonsteroidal anti-inflammatory drugs (NSAIDs) against melanoma report widely varying results. The construction and interpretation of these studies are hampered by many factors, including limited knowledge of the pathogenesis of melanoma, leading to difficulties in determining the relevant factors in the administration of chemopreventive agents and difficulties in assessing long-term use of nonprescription medications. The study by Curiel-Lewandrowski et al. reported in this issue is an important contribution to the literature, but the final verdict regarding the chemopreventive properties of NSAIDs against melanoma is yet to come.

Non-Steroidal Anti-Inflammatory Drugs and Melanoma Risk: Large Dutch Population-Based Case–Control Study

This case-control study investigates the potential chemoprophylactic properties of non-steroidal anti-inflammatory drugs (NSAIDs) on the incidence of cutaneous melanoma (CM). Data were extracted from the Dutch PHARMO pharmacy database and the PALGA pathology database. Cases had a primary CM between 1991 and 2004, were >or=18 years, and were observed for 3 years in PHARMO before diagnosis. Controls were matched for date of birth, gender, and geographical region. NSAIDs and acetylsalicylic acids (ASAs) were analyzed separately. Adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated using multivariable logistic regression, and the results were stratified across gender. A total of 1,318 CM cases and 6,786 controls were eligible to enter the study. CM incidence was not significantly associated with ever ASA use (adjusted OR: 0.92, 95% CI: 0.76-1.12) or ever non-ASA NSAID use (adjusted OR: 1.10, 95% CI: 0.97-1.24). However, continuous use of low-dose ASAs was associated with a significant reduction of CM risk in women (adjusted OR: 0.54, 95% CI: 0.30-0.99) but not in men (OR: 1.01, 95% CI: 0.69-1.47). A significant trend (P=0.04) from no use, non-continuous use to continuous use was observed in women. Continuous use of low-dose ASAs may be associated with a reduced incidence of CM in women, but not in men.

ETORICOXIB: THERAPEUTIC POTENTIAL

The paper describes the therapeutic properties of nonsteroidal anti-inflammatory drugs (NSAID), among them there is etoricoxib, the most selective current COX-2 inhibitor that may be successfully used for both acute analgesia and the treatment of chronic pain in patients with dorsopathies. The important advantages of the drug are its easiness-to-use (once-daily dosing), a wide range of effective doses (from 30 to 120 mg/day), lower risk of gastrointestinal events, liver damage, and skin and respiratory reactions as compared with nonselective NSAIDs, which make etoricoxib an appropriate treatment option if relevant risk factors are present.

Membrane fusion: A new function of non steroidal anti-inflammatory drugs

Membrane fusion is an important event in many biological processes and is characterized by several intermediate steps of which content mixing between the two fusing vesicles signals the completion of the process. Fusion induced solely by small drug molecules is not a common event. Non Steroidal Anti-Inflammatory Drugs (NSAIDs), that control pain and inflammation, are also capable of exhibiting diverse functions. In this study we present a new function of NSAIDs belonging to the oxicam group, as membrane fusogenic agents. Small Unilamellar Vesicles (SUVs) formed by the phospholipid, dimyristoylphosphatidylcholine (DMPC), were used as model membranes. Fluorescence assays using terbium/dipicolinic acid (Tb/DPA) were used to monitor content mixing and corresponding leakage in presence of the drugs. Transmission Electron Microscope (TEM) was also used to image fusion bodies in drug treated vesicles as compared to the untreated ones. The results show that the three oxicam NSAIDs viz. Meloxicam, Piroxicam and Tenoxicam can induce fusion of DMPC vesicles and lead the fusion process to completion at a very low drug to lipid ratio (D/L) of 0.045. The oxicam drugs exhibit differential fusogenic behavior as reflected in the kinetics of content mixing and leakage, both of which can be described by a single exponential rate equation. Moreover, not all NSAIDs can induce membrane fusion. Indomethacin, an acetic acid group NSAID and ibuprofen, a propionic acid group NSAID, did not induce fusion of vesicles. This new property of NSAIDs has important applications in biochemical processes.

Dexamethasone Damages the Rat Stomach but Not Small Intestine During Inhibition of COX-1

We previously reported that inhibition of both COX-1 and COX-2 is required for the gastrointestinal ulcerogenic properties of nonsteroidal anti-inflammatory drugs (NSAIDs). Inhibition of COX-1 up-regulates COX-2 expression, and the prostaglandins (PGs) produced by COX-2 help to maintain the mucosal integrity during inhibition of COX-1. In the present study we investigated whether dexamethasone damages rat gastrointestinal mucosa during inhibition of COX-1 and further developed the idea that COX-2 expression is a key event in the ulcerogenic actions of NSAIDs. Dexamethasone was given p.o. in the absence or presence of SC-560 (a selective COX-1 inhibitor), and the stomach or intestine was examined 8 or 24 hr later, respectively. Neither dexamethasone nor SC-560 alone damaged the gastrointestinal mucosa. In the presence of SC-560, however, dexamethasone damaged the stomach but not small intestine. SC-560 decreased PGE(2) levels in both tissues, with a gradual recovery accompanying the up-regulation of COX-2 expression, and both the recovery of PGE(2) levels and the expression of COX-2 were inhibited by dexamethasone. In the animals treated with SC-560, iNOS expression was up-regulated in the intestinal but not the gastric mucosa, and this response was also inhibited by dexamethasone. These results suggest a risk from steroid therapy in the stomach when COX-2 expression is up-regulated. Dexamethasone does not provoke damage in the intestine, despite inhibiting the up-regulation of COX-2 expression under conditions of PG deficiency; at least one of the reasons is that this agent prevents the expression of iNOS, a major factor in the pathogenesis of intestinal lesions.

Determination of non-steroidal anti-inflammatory drugs in environmental samples by chromatographic and electrophoretic techniques

Non-steroidal anti-inflammatory drugs (NSAIDs) are a group of pharmaceutical compounds widely used in human health care and often found in the aquatic environment, with their metabolites. After an introduction that describes the general problem of drug contamination, the properties of NSAIDs, and environmental risk assessment, this review surveys the chromatographic and electrophoretic methods of analysis in use today for monitoring the most important representatives of this pharmaceutical class in different environmental samples.

Specific Gene Expression and Possible Involvement of Inflammation in Methamphetamine‐Induced Neurotoxicity

To reveal specific gene expression in methamphetamine (METH) -induced dopamine neurotoxicity, temporal characteristics of METH-induced changes in gene expression in dopaminergic neuronal cells were examined using the cDNA array and the differential display method. A number of genes in the class of "trafficking & protein turnover," "metabolic pathways," "transmitters & receptors," and "growth factors, cytokines" were upregulated after the METH treatment in the cDNA array assay. Whereas, some genes related to trafficking & protein turnover and "modulators, effectors & intracellular transducers" were decreased by METH. Some proteins associated with synaptic vesicle transportation indeed up- or downregulated after the METH treatment. These data suggest that the protein trafficking and degradation system is involved in the dopaminergic cell death induced by METH. Furthermore, focusing on inflammatory reactions after METH injection, possible neuroprotective property of nonsteroidal anti-inflammatory drugs were examined against METH-induced neurotoxicity. Coadministration of NSAID with METH significantly attenuated striatal dopamine terminal degeneration and microgliosis induced by METH, suggesting that the protective effects are based on their inhibitory activity on production of cytokines and nitric oxides or their suppressive action against microglia activation.

Ajulemic acid: A novel cannabinoid produces analgesia without a “high”

A long-standing goal in cannabinoid research has been the discovery of potent synthetic analogs of the natural substances that might be developed as clinically useful drugs. This requires, among other things, that they be free of the psychotropic effects that characterize the recreational use of Cannabis. An important driving force for this goal is the long history of the use of Cannabis as a medicinal agent especially in the treatment of pain and inflammation. While few compounds appear to have these properties, ajulemic acid (AJA), also known as CT-3 and IP-751, is a potential candidate that could achieve this goal. Its chemical structure was derived from that of the major metabolite of Δ 9-THC, the principal psychotropic constituent of Cannabis. In preclinical studies it displayed many of the properties of non-steroidal anti-inflammatory drugs (NSAIDs); however, it seems to be free of undesirable side effects. The initial short-term trials in healthy human subjects, as well as in patients with chronic neuropathic pain, demonstrated a complete absence of psychotropic actions. Moreover, it proved to be more effective than placebo in reducing this type of pain as measured by the visual analog scale. Unlike the narcotic analgesics, signs of dependency were not observed after withdrawal of the drug at the end of the one-week treatment period. Data on its mechanism of action are not yet complete; however, the activation of PPAR-γ, and regulation of eicosanoid and cytokine production, appear to be important for its potential therapeutic effects.

Cyclooxygenase-2 modulates cellular growth and promotes tumorigenesis.

Cyclooxygenase (COX)-2 and the prostaglandins resulting from its enzymatic activity have been shown to play a role in modulating cell growth and development of human neoplasia. Evidence includes a direct relationship between COX-2 expression and cancer incidence in humans and animal models, increased tumorigenesis after genetic manipulation of COX-2, and significant anti-tumor properties of non-steroidal anti-inflammatory drugs in animal models and in some human cancers. Recent data showed that COX-2 and the derived prostaglandins are involved in control of cellular growth, apoptosis, and signal through a group of nuclear receptors named peroxisome proliferator-activated receptors (PPARs). In this article we will review some of the findings suggesting that COX-2 is involved in multiple cellular mechanisms that lead to tumorigenesis.

National Cancer Institute Workshop on Chemopreventive Properties of Nonsteroidal Anti-Inflammatory Drugs: Role of COX-Dependent and -Independent Mechanisms

A workshop, “Chemopreventive properties of nonsteroidal anti-inflammatory drugs (NSAIDs): Role of COXdependent and -independent mechanisms,” sponsored by the Chemical and Physical Carcinogenesis Branch, Division of Cancer Biology of the National Cancer Institute, was held in Rockville, Maryland, on January 8, 2001. The workshop was composed of two parts: oral presentations by a series of speakers, and a group discussion of preselected topics.

Development of predictive retention–activity relationship models of non-steroidal anti-inflammatory drugs by micellar liquid chromatography: comparison with immobilized artificial membrane columns

The predictive and interpretative capability of quantitative chromatographic retention–biological activity models is supported by the fact that under adequate experimental conditions the solute partitioning into chromatographic system can emulate the solute partitioning into lipid bilayers of biological membranes, which is the basis for drug and metabolite uptake, passive transport across membranes and bioaccumulation. The use of micellar solutions of Brij35 as mobile phases in reversed-phase liquid chromatography has proven to be valid to predict some biological activities of different kinds of drugs. In this study, quantitative retention–activity relationship (QRAR) models to describe some of the biological activities and pharmacokinetic properties of non-steroidal anti-inflammatory drugs (NSAIDs) with predictive and interpretative ability are obtained. These models are compared with those obtained using immobilized artificial membrane (IAM) column data taken from the literature. For NSAIDs, the statistical characteristics of the micellar liquid chromatography (MLC) QRAR models were better than or at least comparable to those of the IAM-QRAR models.

Role of mucus reduction and luminal acid elevation in increased susceptibility of stomach to nonsteroidal antiinflammatory drug-induced injury in arthritic rats.

We investigated the role of gastric mucus and acid secretion in the increase of nonsteroidal antiinflammatory drug-induced gastric lesions in adjuvant-induced arthritic rats. Both aspirin- and indomethacin-induced gastric injury were remarkably worsened in the arthritic rats. In the arthritic rats, the amounts of mucus glycoprotein in both the mucosa and adherent gel layer were respectively decreased to 70% and 34% of those in normal rats, while gastric acid secretion was augmented to 1.5-fold. The gastroprotective antiulcer agent ecabet sodium, which increased the mucus content in the gel layer but did not affect the luminal acid contents, prevented the increase of both lesions induced by aspirin and indomethacin. Cimetidine also inhibited the formation of aspirin- and indomethacin-induced damage as well as the acid secretion in the arthritic rats. In conclusion, an imbalance between gastric defensive and aggressive systems due to the loss of adherent mucus glycoprotein and the elevation of the luminal acid contents seems to account for the increased susceptibility of the lesion-inducing properties of nonsteroidal antiinflammatory drugs in arthritic rats.

Non-steroidal anti-inflammatory drugs (NSAIDs) block the late, prostanoid-dependent/ceramide-independent component of ovarian IL-1 action: implications for the ovulatory process

The therapeutic efficacy and antiovulatory properties of non-steroidal anti-inflammatory drugs (NSAIDs) is attributed to their ability to suppress prostaglandin endoperoxide synthase (PGS) activity. Given the likely role of interleukin (IL)-1 in the inflammatory (and probably the ovulatory) process, we set out to evaluate whether the antiovulatory property of NSAIDs is attributable, in part, to the inhibition of ovarian IL-1 action. Whole ovarian dispersates from immature rats were cultured under serum-free conditions in the absence or presence of the indicated agents. At the conclusion of the culture period, total RNA was extracted and probed for transcripts corresponding to PGS-1, PGS-2, IL-1β, IL-1 receptor antagonist (IL-1RA) or type I IL-1 receptor (IL-1R) by a solution hybridization/ribonuclease protection assay. Treatment with indomethacin was without significant effect on the early (1 h) response to IL-1β; however, it led to complete and highly significant dose-dependent blockade of the late (48 h) response to IL-1β as assessed in terms of PGS-2 transcripts, proteins and activity. The addition of PGE 2 to cells augmented the ability of IL-1β to upregulate PGS-2 transcripts. Moreover, the addition of PGE 2 to indomethacin-treated cells all but reversed the ability of indomethacin to suppress the IL-1β effect at both the PGS-2 transcript and protein levels. The upregulation by IL-1 of IL-1β, IL-1R and IL-1RA transcripts was similarly inhibited by indomethacin. Taken together, these observations suggest that the anti-ovulatory property of NSAIDs may be due, in part, to blockade of the late, prostanoid-dependent component of ovarian IL-1 action.

The influence of tissue cross-talking on OA progression: role of nonsteroidal antiinflammatory drugs

Osteoarthritis is increasingly recognized as a complex illness in which interrelationships between the different tissues of the joint are important. We are still some way from a complete understanding of the pathophysiologic and temporal relationships between bone, synovial tissue and cartilage. Recent evidence points to a significant role for cytokines and growth factors in osteoarthritis that leads to a preponderance of catabolic processes in the joint.In-vitroculture of human cartilage has been used as a model to measure the effects of drugs used in the treatment of osteoarthritis on anabolic and catabolic processes. On this basis, the nonsteroidal antiinflammatory drugs can be categorized into one of three classes depending on whether they are inhibitory (e.g., indomethacin and naproxen), neutral (e.g., diclofenac, aspirin and piroxicam) or stimulatory (e.g., aceclofenac, tenidap and tolmetin) of glycosaminoglycan synthesis in chondrocytes. The marked differences between these nonsteroidal antiinflammatory drugs suggest that a mechanism other than cyclooxygenase inhibition is involved in their effects on glycosaminoglycan synthesis. Inhibition of IL-1β and the stimulation of growth factors are suggested as possible mechanisms.Although the significance of these properties of nonsteroidal antiinflammatory drugs awaits confirmation inin-vivoand clinical situations, they do provide the clinician with a new parameter with which to choose therapy in osteoarthritis.

Effects of flunixin on movement and performance of Standardbred trotters on the track

An often discussed and controversial issue is the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on performance. The purpose of this study was to investigate the effect of the NSAID flunixin on the movement pattern and performance capacity of Standardbred trotters using a standardised track model. Five adult Standardbred horses in training trotted at 2 occasions with a 2 week interval on the same oval dirt track. Before each occasion the horses were either injected with flunixin meglumine (Finadyne) or normal saline solution i.m. 4 h before the performance test (double blind crossover study). The kinematics for 5 consecutive strides were filmed. There was no significant difference in maximal speed between the saline and flunixin treatment sessions. Significant changes in the movement pattern were observed as an effect of the flunixin treatment. The horses maintained the same stride duration while significantly decreasing stance time and increasing swing time in the forelimbs. The horses' range of limb angle decreased significantly. Heart rates were monitored and plasma lactate and flunixin concentrations were measured. No significant differences were found in heart rate and plasma lactate. The results indicate that flunixin had a significant effect on locomotor pattern while it did not effect metabolic response in these horses (considered to represent a normal race track population). The overall effect on performance in racing horses may therefore be related to the anti-inflammatory and analgesic properties of NSAIDs by masking pain and lameness.

Intestinal tumor load in the Min/+ mouse model is not correlated with eicosanoid biosynthesis.

Several lines of evidence demonstrate an inverse relationship between the use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and aspirin-like drugs, and intestinal cancer. NSAIDs have been shown to reduce the risk of intestinal cancer in humans by 50%.1–4 It is well known that the anti-inflammatory properties of NSAIDs are related to their ability to inhibit prostaglandin biosynthesis. Cyclooxygenase (COX) catalyzes the committed step in prostaglandin formation. Two isoforms of cyclooxygenase exist, COX-1 and COX-2. NSAIDs can inhibit both. COX-1 is the constitutively expressed isoform, and COX-2 is the inducible form of the enzyme involved in inflammation.5–7

Comparison of the cyclooxygenase-1 inhibitory properties of nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors, using sensitive microsomal and platelet assays

Two forms of cyclooxygenase (COX) activity are involved in the synthesis of prostaglandins, prostacyclins, and thromboxanes in mammalian cells. There is now convincing evidence, obtained with a number of structurally distinct inhibitors, that selective COX-2 inhibitors possess anti-inflammatory effects with an improved gastrointestinal tolerability compared with conventional nonsteroidal anti-inflammatory drugs (NSAIDs) affecting both COX-1 and COX-2. As more selective COX-2 inhibitors are being developed, assays with a high degree of sensitivity to inhibition are needed to compare the relative effects of compounds on COX-1 activity. In the present report, we describe a sensitive assay for the inhibition of human COX-1 based on the production of prostaglandin E2 by microsomes from U937 cells incubated with a subsaturating concentration of arachidonic acid. More than 45 NSAIDs and selective COX-2 inhibitors were tested in this assay. IC50 values ranged from 1 nM for flunixin and flurbiprofen to about 200-500 microM for salicylate and acetaminophen. Potent and nonselective NSAIDs such as sulindac sulfide, diclofenac, and indomethacin showed IC50 values of < 20 nM. Among the compounds that have been reported to show selectivity for COX-2, the rank order of potency against COX-1 was DuP 697 > SC-58451 > celecoxib > nimesulide-meloxicam-piroxicam-NS-398-RS-57067 > SC-57666 > SC-58125 > flosulide > etodolac > L-745,337 > DFU-T-614, with IC50 values ranging from 7 nM to 17 microM. A good correlation was obtained between the IC50 values for the inhibition of microsomal COX-1 and both the inhibition of TXB2 production by Ca2+ ionophore challenged platelets and the inhibition of prostaglandin E2 production by CHO cells stably expressing human COX-1. However, the microsomal assay was more sensitive to inhibition than cell-based assays and allowed the detection of inhibitory effects on COX-1 for all NSAIDs and selective COX-2 inhibitors examined with discrimination of their potency under conditions of limited availability of arachidonic acid.

Comparison of the cyclooxygenase-1 inhibitory properties of nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors, using sensitive microsomal and platelet assays

Two forms of cyclooxygenase (COX) activity are involved in the synthesis of prostaglandins, prostacyclins, and thromboxanes in mammalian cells. There is now convincing evidence, obtained with a number of structurally distinct inhibitors, that selective COX-2 inhibitors possess anti-inflammatory effects with an improved gastrointestinal tolerability compared with conventional nonsteroidal anti-inflammatory drugs (NSAIDs) affecting both COX-1 and COX-2. As more selective COX-2 inhibitors are being developed, assays with a high degree of sensitivity to inhibition are needed to compare the relative effects of compounds on COX-1 activity. In the present report, we describe a sensitive assay for the inhibition of human COX-1 based on the production of prostaglandin E2 by microsomes from U937 cells incubated with a subsaturating concentration of arachidonic acid. More than 45 NSAIDs and selective COX-2 inhibitors were tested in this assay. IC50 values ranged from 1 nM for flunixin and flurbiprofen to about 200-500 microM for salicylate and acetaminophen. Potent and nonselective NSAIDs such as sulindac sulfide, diclofenac, and indomethacin showed IC50 values of < 20 nM. Among the compounds that have been reported to show selectivity for COX-2, the rank order of potency against COX-1 was DuP 697 > SC-58451 > celecoxib > nimesulide-meloxicam-piroxicam-NS-398-RS-57067 > SC-57666 > SC-58125 > flosulide > etodolac > L-745,337 > DFU-T-614, with IC50 values ranging from 7 nM to 17 microM. A good correlation was obtained between the IC50 values for the inhibition of microsomal COX-1 and both the inhibition of TXB2 production by Ca2+ ionophore challenged platelets and the inhibition of prostaglandin E2 production by CHO cells stably expressing human COX-1. However, the microsomal assay was more sensitive to inhibition than cell-based assays and allowed the detection of inhibitory effects on COX-1 for all NSAIDs and selective COX-2 inhibitors examined with discrimination of their potency under conditions of limited availability of arachidonic acid.

Solubility and solubilization properties of non-steroidal anti-inflammatory drugs

Ten non-steroidal anti-inflammatory drugs (NSAID) of the acetic and propionic classes were analyzed in the form of salts to disclose the solubilization property of their aqueous solutions toward a lipid probe (the azo-dye Orange OT). This property is related to the self-aggregation of the anions above a concentration value that differs for each drug: indomethacin and fenclofenac showed solubilization ability in the form of sodium salts in pure water (starting from 30 and 40 mM, respectively); these values decreased with increasing ionic strength. In the case of diclofenac it was necessary to use a salt prepared with an organic base, that displayed a solubility higher than that of the sodium salt, required to overcome the critical value (35 mM). Naproxen, sulindac, ketoprofen, indoprofen were used at high concentrations of their sodium salts (100–160 mM) and solubilize the dye in the presence of a high total ionic strength. Alclofenac did not display solubilization ability; fenbufen and ibuprofen were tested as salts of an organic base: results were not conclusive because the presence of the organic base in the salt form and in the solution, as added electrolyte for the ionic strength, affected the results of the solubilization tests. The results are briefly discussed in terms of hydrophilic/hydrophobic balance present on the anion of the NSAID examined, as evaluated by the fragment constant approach.