The enantiomers of etodolac, a racemic anti-inflammatory agent, play different roles in efficacy and gastrointestinal safety

R-etodolac is a more potent Wnt signaling inhibitor than enantiomer, S-etodolac

Etodolac is an FDA-approved nonsteroidal anti-inflammatory drug (NSAID) used to treat a variety of inflammatory diseases. The drug is administered as a racemate (50/50 mixture of R- and S- enantiomers), however, studies have shown that the two enantiomers have distinct biologic and pharmacokinetic differences. Wnt signaling, which plays key roles in cell proliferation, polarity, and differentiation, has been shown to be inhibited by R-etodolac; however, comparative analyses of R- and S-etodolac in this function have not been conducted. We used in silico molecular docking and TOPflash functional biologic assays to compare R- and S-enantiomers effect on Wnt signaling inhibition. Further, we used a cultivated limbal stem epithelial cell (cLSCs) model to investigate enantiospecific changes in the colony-forming efficiency (CFE) of cLSCs. The data shows that R-etodolac is a more potent inhibitor of Wnt signaling. In addition, consistently, while both enantiomers demonstrate a dose-dependent decrease in CFE of cLSCs, R-etodolac is a more potent inhibitor.

Combined Use of Cu(II)-L-Histidine Complex and β-Cyclodextrin for the Enantioseparation of Three Amino Acids by CE and a Study of the Synergistic Effect

A new capillary electrophoresis method was applied to chiral separation of three amino acids, including D,L-tryptophan, D,L-tyrosine and D,L-phenylalanine. The chiral resolution was attained in an untreated fused-sillica capillary using a dual chiral selector, which was made up of Cu(II)-L-histidine complex and β-cyclodextrin (CD). The cardinal factors influencing its separation efficiency, such as chiral selectors, buffer pH and applied voltage, were optimized. Best results were acquired by using a buffer consisting of 10 mmol/L Cu(II), 13 mmol/L L-histidine, 8 mmol/L β-CD, 5 mmol/L phosphate adjusted to pH 5.0 and 15 kV applied voltage. All enantiomers were entirely resolved within 20 min with high resolutions of 3.6~6.1. The analysis method was verified through the determination of D,L-tryptophan in terms of linearity, precision and accuracy. And the robustness of this method was proved. The Limit of Detection and Limit of Quantification for both enantiomers were 2.5 and 5 μg/mL, respectively. The method was perfectly applied to the determination of the enantiomeric purity of L-tryptophan. Furthermore, the interaction between Cu(II)-L-histidine complex and β-CD was also studied using Ultraviolet-visible and 1H NMR spectroscopy to explain the synergistic effect involved. The results illustrated that Cu(II)-L-histidine complex and β-CD played a synergistic role in the enantiomeric separation of chiral drugs, with good prospects for application.

Albumin-Based Transport of Nonsteroidal Anti-Inflammatory Drugs in Mammalian Blood Plasma

Every day, hundreds of millions of people worldwide take nonsteroidal anti-inflammatory drugs (NSAIDs), often in conjunction with multiple other medications. In the bloodstream, NSAIDs are mostly bound to serum albumin (SA). We report the crystal structures of equine serum albumin complexed with four NSAIDs (ibuprofen, ketoprofen, etodolac, and nabumetone) and the active metabolite of nabumetone (6-methoxy-2-naphthylacetic acid, 6-MNA). These compounds bind to seven drug-binding sites on SA. These sites are generally well-conserved between equine and human SAs, but ibuprofen binds to both SAs in two drug-binding sites, only one of which is common. We also compare the binding of ketoprofen by equine SA to binding of it by bovine and leporine SAs. Our comparative analysis of known SA complexes with FDA-approved drugs clearly shows that multiple medications compete for the same binding sites, indicating possibilities for undesirable physiological effects caused by drug-drug displacement or competition with common metabolites. We discuss the consequences of NSAID binding to SA in a broader scientific and medical context, particularly regarding achieving desired therapeutic effects based on an individual's drug regimen.

Etodolac Containing Topical Niosomal Gel: Formulation Development and Evaluation

The present study aimed to investigate the delivery potential of Etodolac (ETD) containing topical niosomal gel. Niosomal formulations were prepared by thin film hydration method at various ratios of cholesterol and Span 60 and were evaluated with respect to particle size, shape, entrapment efficiency, and in vitro characteristics. Dicetyl phosphate (DCP) was also added in the niosomal formulation. Mean particle size of niosomal formulation was found to be in the range of 2 μm to 4 μm. Niosomal formulation N2 (1 : 1) ratio of cholesterol and surfactant displayed good entrapment efficiency (96.72%). TEM analyses showed that niosomal formulation was spherical in shape. Niosomal formulation (N2) displayed high percentage of drug release after 24 h (94.91) at (1 : 1) ratio of cholesterol : surfactant. Further selected niosomal formulation was used to formulate topical gel and was characterized with respect to its various parameters such as pH, viscosity, spreadability, ex vivo study, and in vivo potential permeation. Ex vivo study showed that niosomal gel possessed better skin permeation study than the plain topical gel. Further in vivo study revealed good inhibition of inflammation in case of topical niosomal gel than plain gel and niosomal formulation. The present study suggested that topical niosomal gel formulations provide sustained and prolonged delivery of drug.

Etodolac blocks the allyl isothiocyanate-induced response in mouse sensory neurons by selective TRPA1 activation

BACKGROUND AND PURPOSE

The excitability of nociceptors is modulated by the transient receptor potential cation channel, ankyrin subfamily, member 1 (TRPA1). We have previously reported that etodolac, a nonsteroidal anti-inflammatory drug, attenuates mechanical allodynia in a mouse model of neuropathic pain by a mechanism that is independent of cyclooxygenase inhibition. Here, we investigate the role of TRPA1 in the mechanism of the antinociceptive action of etodolac in vitro and in vivo.

EXPERIMENTAL APPROACH

Ca(2+) influx was measured in HEK-293 cells expressing mouse TRPA1 and in mouse dorsal root ganglion (DRG) neurons. The effect of etodolac on the nociceptive behavior induced in mice by the TRPA1 agonist allyl isothiocyanate (AITC) was also measured.

RESULTS

Etodolac induced Ca(2+) influx in HEK-293 cells expressing mouse TRPA1 and in mouse DRG neurons. The Ca(2+) influx induced by etodolac was inhibited by pretreatment with the TRPA1-specific antagonist HC-030031. In contrast, etodolac did not induce Ca(2+) influx in cells expressing TRPV1, TRPV2 or TRPM8. In addition, pretreatment with etodolac inhibited the Ca(2+) influx induced by AITC.

CONCLUSION AND IMPLICATION

Etodolac showed a selective TRPA1 agonist action, providing evidence that etodolac desensitizes nociceptors by the selective activation of TRPA1. Etodolac may be clinically useful in the treatment of neuropathic pain.

The Pattern of Use of Oral NSAIDs with or without Co-prescription of Gastroprotective Agent for Arthritic Knee by Korean Practitioners

PURPOSE

The aim of this study was to describe the patterns of use of non-steroidal anti-inflammatory drugs (NSAIDs) for arthritic knees in clinical practice, particularly focusing on the co-prescription of gastroprotective agents for patients with risk factors for adverse gastrointestinal (GI) events.

MATERIALS AND METHODS

Each cross-sectional cohort was a group of outpatients visiting 111 physicians who had prescribed NSAIDs for the patients' arthritic knees for more than three consecutive months. A self-administered questionnaire was completed by each patient and physician.

RESULTS

Nine hundred and forty five patients (48%) of the whole 1,960 patients belonged to the group with a high or very high risk for NSAID-induced gastropathy determined by northern California Health Maintenance Organization guidelines. Overall, only less than half of the patients were given co-prescription of gastroprotective agents, regardless of the presence or absence of GI symptoms and irrespective of the level of risk for NSAID-induced gastropathy.

CONCLUSIONS

The physician prescribing NSAIDs for arthritic knees should monitor any GI symptoms and the patient monitor anylevel for NSAIDinduced gastropathy, and be willing to add gastroprotective agents as necessary in order to prevent serious adverse GI events.