Propellant Free Pressurized Spray System of Etodolac to Manage Acute Pain Conditions: In Vitro and In Vivo Evaluation.

This study aimed to develop a propellant-free topical spray formulation of Etodolac (BCS-II), a potent NSAID, which could be beneficial in the medical field for the effective treatment of pain and inflammation conditions. The developed novel propellant-free spray formulation is user-friendly, cost-effective, propellant-free, eco-friendly, enhances the penetration of Etodolac through the skin, and has a quick onset of action. Various formulations were developed by adjusting the concentrations of different components, including lecithin, buffering agents, film-forming agents, plasticizers, and permeation enhancers. The prepared propellant-free spray formulations were then extensively characterized and evaluated through various in vitro, ex vivo, and in vivo parameters. The optimized formulation exhibits an average shot weight of 0.24 ± 0.30 ml and an average drug content or content uniformity of 87.3 ± 1.01% per spray. Additionally, the optimized formulation exhibits an evaporation time of 3 ± 0.24 min. The skin permeation study demonstrated that the permeability coefficients of the optimized spray formulation were 21.42 cm/h for rat skin, 13.64 cm/h for mice skin, and 18.97 cm/h for the Strat-M membrane. When assessing its potential for drug deposition using rat skin, mice skin, and the Strat-M membrane, the enhancement ratios for the optimized formulation were 1.88, 2.46, and 1.92, respectively against pure drug solution. The findings from our study suggest that the propellant-free Etodolac spray is a reliable and safe topical formulation. It demonstrates enhanced skin deposition, and improved effectiveness, and is free from any skin irritation concerns.

Enhanced Oral Bioavailability of Etodolac by the Liquisolid Compact Technique: Optimisation, In-Vitro and In-Vivo Evaluation.

BACKGROUND: Poor dissolution of Etodolac is one of the major challenges in achieving the desired therapeutic effect in oral therapy. OBJECTIVE: This study aimed to assess the potential of the liquisolid compact technique in increasing the rate of dissolution of Etodolac and thus its bioavailability. METHODS: Liquisolid compacts were prepared using PEG 400, Avicel PH-200 and Aerosil 200 as non-volatile liquid, carrier and coating material, respectively. The optimisation was carried out by applying a 32 full factorial design using Design expert software 11.0.3.0 to examine the effects of independent variables (load factor and carrier: coating ratio) on dependent variables (angle of repose and % cumulative drug release at 30 min [Q _{30 min]). Assessment of bioavailability was based on a pharmacokinetic study on rabbits and pharmacodynamics evaluation on rats, respectively. RESULTS: The formulation M3 was identified as the optimised formulation based on the better flow (lower angle of repose) and a higher rate of dissolution (Q 30 min >95%). The higher dissolution rate could be due to conversion of Etodolac into an amorphous molecularly dispersed state, availability of larger surface area, enhancement of aqueous solubility and enhanced wetting of drug particles. Studies with DSC, XRD, and SEM verified the transformation of Etodolac from crystalline to amorphous state, a key factor responsible for improving the dissolution rate. The pharmacokinetic profile of M3 was prominent, demonstrating higher absorption of Etodolac in comparison to oral suspension and immediate-release conventional tablets in rabbits. Liquisolid formulation exhibited a 27% increment in paw thickness as compared to 57% and 46% increments for oral suspension and immediate-release conventional tablets, respectively, after 7 hrs in the carrageenan-induced paw model in rats. CONCLUSION: The results indicated the liquisolid compact technique to be a promising strategy to enhance the bioavailability of Etodolac.}

Pharmacokinetic modeling and simulation of etodolac following single oral administration in dogs.

Etodolac is a nonsteroidal anti-inflammatory drug with selective cyclooxygenase-2 inhibition to treat pain and inflammation associated with osteoarthritis in humans and dogs. The aim of the study was to investigate the pharmacokinetics of etodolac following single oral administration of 200 mg to 10 healthy beagle dogs. The plasma concentrations of etodolac were detected using liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was conducted using the noncompartmental method and modeling approaches. Etodolac was rapidly absorbed (Tmax = 0.85 h, Ka = 1.49 h-1) and slowly eliminated (T1/2 = 39.55 h) following oral administration to the dogs. A two-compartment pharmacokinetic model with first-order absorption and elimination rate constants was successfully explained for the pharmacokinetic aspects of etodolac in dogs. From a Monte Carlo simulation (1000 repetitions), the accumulation index and AUCτ at steady state were predicted as 1.60 [90% confidence intervals (CI), 1.24-2.81] and 408.18 ng·hr/mL [90% CI, 271.26-590.58 ng·hr/mL], respectively. This study will help to enact a more accurate optimal dosing regimen of etodolac in dogs with osteoarthritis, and may be useful in developing a novel formulation of etodolac for human in the future.

Preparation, Characterization and In Vitro / In Vivo Evaluation of Oral Time-Controlled Release Etodolac Pellets.

The objective of this study was to prepare time-controlled release etodolac pellets to facilitate drug administration according to the body's biological rhythm, optimize the drug's desired effects, and minimize adverse effects. The preparation consisted of three laminal layers from center to outside: the core, the swelling layer, and the insoluble polymer membrane. Factors influenced the core and the coating films were investigated in this study. The core pellets formulated with etodolac, lactose, and sodium carboxymethyl starch (CMS-Na) were prepared by extrusion-spheronization and then coated by a fluidized bed coater. Croscarmellose sodium (CC-Na) was selected as the swelling agent, and ethyl cellulose (EC) as the controlled release layer. The prepared pellets were characterized by scanning electron microscopy and evaluated by a dissolution test and a pharmacokinetic study. Compared with commercial available capsules, pharmacokinetics studies in beagle dogs indicated that the prepared pellets release the drug within a short period of time, immediately after a predetermined lag time. A good correlation between in vitro dissolution and in vivo absorption of the pellets was exhibited in the analysis.

Development of an Enantioselective and Biomarker-Informed Translational Population Pharmacokinetic/Pharmacodynamic Model for Etodolac.

Cyclooxygenase-2 (COX-2) isoform has a critical role in the development of pain. Inhibition of COX-2 in vitro serves as a biomarker for nonsteroidal anti-inflammatory drugs (NSAIDs). The NSAID concentrations yielding 80% COX-2 inhibition (IC80) correlate with therapeutic doses to achieve analgesia across multiple COX-2 inhibitors. However, there are no time-course models relating COX-2 inhibition with decreased pain. This study aimed to characterize the relationship between NSAID concentrations, in vitro COX-2 inhibition, and acute pain decrease in humans over time by a translational approach using clinical pharmacokinetic and literature reported in vitro and clinical pharmacodynamic data. In a two-way cross-over study, eight healthy volunteers received 300 and 400 mg racemic etodolac, a preferential COX-2 inhibitor. R- and S-etodolac were determined by LC-MS/MS and simultaneously modeled. Literature in vitro IC50 data for COX-2 inhibition by S-etodolac were used to fit adjusted pain score profiles from dental patients receiving etodolac. External model qualification was performed using published ibuprofen data. Etodolac absorption was highly variable due to gastric transit kinetics and low aqueous solubility. The disposition parameters differed substantially between enantiomers with a total clearance of 2.21 L/h for R-etodolac and 26.8 L/h for S-etodolac. Volume of distribution at steady-state was 14.6 L for R-etodolac and 45.8 L for S-etodolac. Inhibition of COX-2 by 78.1% caused a half-maximal pain decrease. The time-course of pain decrease following ibuprofen was successfully predicted via the developed translational model. This proposed enantioselective pharmacodynamic-informed approach presents the first quantitative time-course model for COX-2 induced pain inhibition in patients.

Etodolac transdermal cubosomes for the treatment of rheumatoid arthritis: ex vivo permeation and in vivo pharmacokinetic studies.

In this study, transdermal etodolac-loaded cubosomes were developed in order to relieve patient pain and joints stiffness by providing stable etodolac concentration at the targeting sites through controlled drug delivery via the noninvasive skin route with more sustaining and less frequent dosing. Different ratios and percentages of poloxamer 407 and monoolein were used to formulate the cubosomes using emulsification and homogenization processes. The etodolac-loaded cubosomes showed particle size values ranging from 135.95 to 288.35 nm and zeta potential values ranging from -18.40 to -36.10 mV. All the cubosomes offered an encapsulation efficiency value of about 100% and showed drug loading capacity ranging from 1.28 to 6.09%. The in vitro drug release studies revealed a controlled drug release profile with a drug release rate up to 15.08%/h. Increasing poloxamer concentration in etodolac-loaded cubosomes resulted in nanoparticles with less particle size and faster drug release. The particles exhibited cubic and hexagonal shapes. The DSC and X-ray analysis demonstrated that the drug was encapsulated in the cubosomes bicontinuous structures in amorphous form. In addition, investigated cubosomes exhibited fast drug penetration through excited mice skin followed by slower drug penetration for up to 24 h. The pharmacokinetic study in human volunteers showed that the selected etodolac-loaded cubosomes enhanced the bioavailability of etodolac as compared to the oral capsules (266.11%) with evidence of longer half-life and higher MRT that reached 18.86 and 29.55 h, respectively. The etodolac-loaded cubosomes propose a promising system for treatment of arthritis simply through skin application.

Quantification of Etodolac in Human Plasma for Pharmacokinetics and Bioequivalence Studies in 27 Korean Subjects.

OBJECTIVE: We developed a simple and validated liquid chromatography tandem mass spectrometry( LC-MS/MS) for quantification of etodolac using pioglitazone as an internal standard (IS) to assess pharmacokinetics and to appraise bioequivalence of two formulations of etodolac (reference and tested) in 27 healthy Korean subjects. METHODS: Isocratic mobile phase consisted of 10 mM ammonium formate and acetonitrile were used to separate the analytes on a Gemini C18 column. Also, analytes were analyzed by MS/MS in multiple reaction monitoring (MRM) mode using the transitions of (M+H)+ ions, m/z 288.2→ 172.3 and m/z 357.1→ 134.2 for quantification of etodolac and IS each. The standard calibration curves displayed significant linearity within the range of 0.2-30.0 µ g/mL (r2=0.9956, 1/x2 weighting) with LLOQ of 0.1 µg/mL. RESULTS: The retention times of etodolac and the IS were 0.77 min and 0.57 min each, indicating the high-throughput potential of the proposed method. The pharmacokinetic parameters were calculated from the plasma samples and data form the reference and test drugs were represented as follows; Area under plasma concentration-time curve (AUCt) (78.03 vs. 84.00 µgxh/mL), AUC∞ (86.67 vs. 93.92 µgxh/mL), maximal plasma concentration (Cmax) (19.49 vs. 18.94 µg/mL), time for maximal concentrations (Tmax) (2.13 vs. 2.26 h), Plasma elimination half-life (T1/2) (8.12 vs. 8.47 h), elimination rate constant (λz) (0.0853 vs. 0.0818 h-1). Pharmacokinetic parameters with 90% confidence interval fall within the bioequivalence range of 80-125%. CONCLUSION: Thus, the new testified method was successfully applied for the pharmacokinetic and bioequivalence studies for two etodolac formulations.

An ionic liquid-in-water microemulsion as a potential carrier for topical delivery of poorly water soluble drug: Development, ex-vivo and in-vivo evaluation.

In this paper, we report an ionic liquid-in-water (IL/w) microemulsion (ME) formulation which is able to solubilize etodolac (ETO), a poorly water soluble drug for topical delivery using BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) as IL, Tween 80 as surfactant and ethanol as co-surfactant. The prepared ME was characterized for physicochemical parameters, subjected to ex-vivo permeation studies as well as in-vivo pharmacodynamic evaluation. The ex-vivo drug permeation studies through rat skin was performed using Franz-diffusion cell and the IL/w based ME showed maximum mean cumulative percent permeation of 99.030±0.921% in comparison to oil-in-water (o/w) ME (61.548±1.875%) and oily solution (48.830±2.488%) of ETO. In-vivo anti-arthritic and anti-inflammatory activities of the prepared formulations were evaluated using different rodent models and the results revealed that ETO loaded IL/w based ME was found to be more effective in controlling inflammation than oily solution, o/w ME and marketed formulation of ETO. Histopathological studies also demonstrated that IL/w based ME caused no anatomical and pathological changes in the skin.

Enantioselective HPLC-DAD method for the determination of etodolac enantiomers in tablets, human plasma and application to comparative pharmacokinetic study of both enantiomers after a single oral dose to twelve healthy volunteers.

An enantioselective high performance liquid chromatographic method with diode array detection (HPLC-DAD) was developed and validated for the determination of etodolac enantiomers in tablets and human plasma. Enantiomeric separation was achieved on a Kromasil Cellucoat chiral column (250 mm × 4.6mm i.d., 5 µm particle size) using a mobile phase consisting of hexane: isopropanol: triflouroacetic acid (90:10:0.1 v/v/v) at a flow rate of 1.0 mL min(-1). The chromatographic system enables the separation of the two enantiomers and the internal standard within a cycle time of 8 min. The resolution between the two enantiomers was 4.25 and the resolution between each enantiomer and the internal standard was more than 2.0. Detection was carried out at 274 nm, and the purity assessment was performed using a photodiode array detector. Solid phase extraction technique using C-18 cartridge was applied to extract the analytes from the plasma samples, and the percentage recovery was more than 95% for the lower quantification limit. The method has been validated with respect to selectivity, linearity, accuracy and precision, robustness, limit of detection and limit of quantification. The validation acceptance criteria were met in all cases. The linearity range for the determination of each enantiomer in human plasma was 0.4-30.0 µg mL(-1) and the limits of quantification of R-etodolac and S-etodolac were 0.20 and 0.19 µg mL(-1), respectively. The validated method was successfully applied to the determination of etodolac enantiomers in tablets and to a comparative pharmacokinetic study of the two enantiomers after the administration of 300 mg single oral dose etodolac racemate tablets to twelve healthy volunteers.

Comparison of the effect of Naproxen, Etodolac and Diclofenac on postoperative sequelsfollowing third molar surgery: A randomised, double-blind, crossover study

OBJECTIVE: To compare the three non-steroidal anti-inflammatory agents (NSAIDs) Diclofenac potassium, Etodolac and Naproxen sodium in relation to pain, swelling and trismus following impacted third molar surgery. Study DESIGN: The study was a randomized and a double-blinded study which included 42 healthy young individuals with impacted third molars and bone retention. Patients were randomly assigned to 3 groups (n: 14) to which Diclofenac potassium, Naproxen sodium and Etodolac were administered orally an hour before the operation. Impacted third molars were surgically extracted with local anaesthesia. Visual analog scales (VAS) were used to assess the pain in the 6th, 12th hours and on the 1st, 2nd, 3rd, 5th, and 7th days postoperatively. Swelling was evaluated using ultrasound (US) and mouth opening (trismus) was measured with a composing stick pre and post operatively on the 2nd and 7th days respectively. RESULTS: Regarding pain alleviation, Diclofenac potassium was better than Naproxen sodium and Naproxen sodium was better than Etodolac but these differences were not statistically significant. US measurements showed that the swelling on postoperative 2nd day was significantly lowest with Diclofenac potassium as compared to others (p= 0.027) while Naproxen sodium and Etodolac acted similarly (p = 0.747). No difference was noted regarding trismus in any of the groups. CONCLUSION: NSAIDs (Diclofenac, Naproxen and Etodolac) are somehow similarly effective for controlling pain and trismus following extraction of mandibular third molars but Diclofenac potassium surpasses others in reduction of swelling

Development and in vitro/in vivo evaluation of etodolac controlled porosity osmotic pump tablets.

The aim of the current work was the design and evaluation of etodolac controlled porosity osmotic pump (CPOP) tablets exhibiting zero-order release kinetics. Variables influencing the design of (1) core tablets viz., (a) osmogent type (sodium chloride, potassium chloride, mannitol, and fructose) and (b) drug/osmogent ratio (1:0.25, 1:0.50, and 1:0.75), and (2) CPOP tablets viz., (a) coating solution composition, (b) weight gain percentage (1-5%, w/w), and (c) pore former concentration (5%, 10%, and 20%, v/v), were investigated. Statistical analysis and kinetic modeling of drug release data were estimated. Fructose-containing core tablets showed significantly (P < 0.05) more retarded drug release rates. An inverse correlation was observed between drug/fructose ratio and drug release rate. Coating of the optimum core tablets (F4) with a mixture of cellulose acetate solution (3%, w/v), diethyl phthalate, and polyethylene glycol 400 (85:10:5, v/v, respectively) till a 4% w/w weight gain enabled zero-order sustained drug delivery over 24 h. Scanning electron microscopy micrographs of coating membrane confirmed pore formation upon contact with dissolution medium. When compared to the commercial immediate-release Napilac® capsules, the optimum CPOP tablets (F4-34) provided enhanced bioavailability and extended duration of effective etodolac plasma concentration with minimum expected potential for side effects in healthy volunteers.

Polymeric surfactant based etodolac chewable tablets: formulation and in vivo evaluation.

Etodolac (ET) is a nonsteroidal anti-inflammatory drug with proved potential antitumor and uric acid lowering effects. It shows dissolution rate-dependent bioavailability. This work was carried out to improve the dissolution rate of etodolac using three carriers of known potential to improve solubility and hence dissolution rate of poorly soluble drugs through coevaporation technique. The polymeric surfactant inutec, 2-hydroxypropyl-ß-cyclodextrin, and tromethamine were used at three different drug/carrier ratios. The dissolution rate of ET at pH 1.2 and 6.8 is improved in all of the solid dispersion systems compared to that of the pure drug and physical mixtures. DSC of coevaporates at 1:5 drug/carrier ratio providing the fastest dissolution rate suggested loss of ET crystallinity which was further confirmed by X-ray diffraction. Inutec-based coevaporate was chosen for the formulation of ET chewable tablets. Chewable tablets (F3) that met the USP monograph specifications for ET tablets, with 86% dissolved amount within 15 min, was chosen for in vivo absorption study in comparison with pure ET-filled hard gelatin capsules. The results showed significantly higher mean C (max) and shorter mean T (max) (about 2 h earlier) and about 1.32-fold higher mean AUC(0-24) values for the F3 chewable tablets compared to ET-filled capsules.

Enhanced oral bioavailability of etodolac by self-emulsifying systems: in-vitro and in-vivo evaluation.

OBJECTIVES: The objective of this study was to prepare a self-emulsifying drug delivery system (SEDDS) for oral bioavailability enhancement of a poorly water-soluble drug, etodolac. The SEDDS formulations were optimized by evaluating their ability to self-emulsify when introduced to an aqueous medium under gentle agitation, and by determination of the particle size of the resulting emulsion. METHODS: An optimized formulation of SEDDS (composed of 20% etodolac, 30% oil Labrafac WL1349, 10% Lauroglycol 90 and 40% Labrasol) was selected for bioavailability assessment in rabbits. The anti-inflammatory effect was also determined in rats, and compared with powder drug and etodolac suspension in water (50 mg/kg). KEY FINDINGS: The peak plasma concentration of 16.4 +/- 1.1 microg/ml appeared after 1.3 +/- 0.2 h, whereas with powder drug and etodolac suspension the values were 7.5 +/- 0.5 and 10.6 +/- 0.7 microg/ml at 4.2 +/- 0.4 and 2.4 +/- 0.2 h, respectively. The AUC(0-8) of the etodolac SEDDS formulation was 2.3 times that of the pure drug and 1.4 times that of the suspension form. SEDDS formulation exhibits a 21% increase in paw thickness compared with a 39% increase on oral administration of etodolac suspension after 4 h at the same dose of the drug (20 mg/kg). CONCLUSIONS: The result indicates the utility of SEDDS for the oral delivery of etodolac and potentially other lipophilic drugs.

Phase I study of a novel pro-apoptotic drug R-etodolac in patients with B-cell chronic lymphocytic leukemia.

R-etodolac is a novel pro-apoptotic agent with potential antitumor activity against B-cell chronic lymphocytic leukemia (B-CLL). This phase I clinical trial was conducted to determine the tolerability, safety, and maximum tolerated dose (MTD) of R-etodolac, administered orally twice a day (BID), in patients with B-CLL. Secondary objectives included evaluating clinical response, pharmacodynamic activity (reduction of lymphocytes), and pharmacokinetic (PK) profile. Forty-three patients were enrolled in the study. The most frequently reported adverse events were diarrhea, rash, pruritus, and headache. Increases in alanine aminotransferase (ALT) were also observed. Adverse events were generally mild and self-limiting, although in an apparent dose-response relationship, grade 2 and 3 gastrointestinal toxicities and grade 3 skin toxicities were reported with the highest dose regimens (1,800 and 2,400 mg BID). Hematologic toxicity was rare. The MTD was determined to be 1,200 mg BID. PK results indicated that oral absorption of R-etodolac was rapid (time to maximum concentration ranged from 2 to 4 h), and the half-life ranged from 5 to 7 h. The increase in maximum concentration, however, was not proportional to the increase in dose. R-etodolac significantly reduced absolute lymphocyte count (ALC) in B-CLL patients in a dose-dependent manner up to 1,800 mg BID and caused partial responses in 2 patients. Further study of R-etodolac as a possible new maintenance therapy or as a part of combination therapy of B-CLL appears warranted.

In vitro and ex vivo permeation studies of etodolac from hydrophilic gels and effect of terpenes as enhancers.

Etodolac, a highly lipophilic anti-inflammatory drug, is widely used in rheumatoid arthritis usually at an oral dose of 200 mg twice daily. The commonest side effects during therapy with etodolac is generally gastrointestinal disturbances these are usually mild and reversible but in some patients are peptic ulcer and severe gastrointestinal bleeding. To eliminate these side effects and obtain high drug concentration at the application side, dermal application of etodolac seems to be an ideal route for administration. Hydrophilic gel formulations of etodolac were prepared with carboxymethylcellulose sodium. The effect of different terpenes (anethole, carvacrol, and menthol) as an enhancer on the percutaneous absorption of etodolac was also investigated. Permeation studies were carried out with unjacketed modified horizontal diffusion cells through cellulose membrane and rat skin. In vitro studies with cellulose membrane showed that all formulations presented the same drug release profile (p > 0.05). Ex vivo studies with excised rat skin revealed that etodolac was released and penetrated into rat skin quickly. Anethole, a hydrophobic terpene, enhanced the absorption of etodolac significantly (p < 0.05). This result is consistent with the fact that hydrophobic terpenes are effective on the percutaneous absorption of lipophilic drugs. Menthol and carvacrol, hydrophilic terpenes, did not enhance the absorption of etodolac. The lipophilicity of the enhancers seems an important factor in promoting penetration of etodolac through the skin. Since etodolac creates gastrointestinal disturbances, topical formulations of etodolac in gel form including 1% anethole could be an alternative.

Pharmacokinetics of etodolac in the horse following oral and intravenous administration.

The purpose of this study was to determine the pharmacokinetics of etodolac following oral and intravenous administration to six horses. Additionally, in vitro cyclooxygenase (COX) selectivity assays were performed using equine whole blood. Using a randomized two-way crossover design, horses were administered etodolac (20 mg/kg) orally or intravenously, with a minimum 3-week washout period. Plasma samples were collected after administration for analysis using high pressure liquid chromatography with ultraviolet detection. Following intravenous administration, etodolac had a mean plasma half-life (t(1/2)) of 2.67 h, volume of distribution (Vd) of 0.29 L/kg and clearance (Cl) of 234.87 mL/h kg. Following oral administration, the average maximum plasma concentration (Cmax)) was 32.57 mug/mL with a t(1/2) of 3.02 h. Bioavailability was approximately 77.02%. Results of in vitro COX selectivity assays showed that etodolac was only slightly selective for COX-2 with a COX-1/COX-2 selectivity ratio effective concentration (EC)50 of 4.32 and for EC80 of 4.77. This study showed that etodolac is well absorbed in the horse after oral administration, and may offer a useful alternative for anti-inflammatory treatment of various conditions in the horse.

Nonsteroidal antiinflammatory drugs: a review.

The increasing use of nonsteroidal antiinflammatory drugs (NSAIDs) in small animals has resulted in the development of new and innovative additions to this class of drugs. Examples of NSAIDs now available for use in small animals include aspirin, etodolac, carprofen, ketoprofen, meloxicam, deracoxib, and tepoxalin. The purposes of this article are to review the pathophysiology of prostaglandin synthesis and inhibition, the mechanisms of action, pharmacokinetics, pharmacological effects, and potential adverse reactions of aspirin and the newly released NSAIDs.

Pharmacokinetic difference between S-(+)- and R-(-)-etodolac in rats.

AIM: To study whether etodolac enantiomers have pharmacokinetic difference after oral administration. METHODS: Fourteen rats, divided into two groups randomly, were orally given S-(+)- or R-(-)-etodolac at a single dose of 20 mg/kg, respectively. Blood samples were collected before and at 5, 10, 20, 30 min and 1, 3, 6, 12, 24, 48, 72 h after treatment. The plasma samples were analyzed with a high-performance liquid chromatographic method. RESULTS: The calibration curves were linear in the range of 0.5-50.0 mg/L (r=0.9999) to S-(+)-etodolac and 2.0-200.0 mg/L (r=0.9999) to R-(-)-etodolac, respectively. The main pharmacokinetic parameters of S-(+)- and R-(-)-etodolac were as follows: t1/2(lambdaz) 18+/-4 h vs 19.4+/-2.2 h, tmax 3.3+/-2.6 h vs 4+/-4 h; Cmax 29+/-6 mg/L vs 97+/-14 mg/L, AUC0-t 706+/-100 h.mg.L(-1) vs 2940+/-400 h mg.L(-1), CL(s) 0.030+/-0.006 L.kg(-1).h(-1) vs 0.0065+/-0.0010 L.kg(-1).h(-1) and V/F 0.25+/-0.22 L.kg(-1) vs 0.03+/-0.05 L.kg(-1). There was no significant difference in t1/2(lambdaz), and tmax between S-(+)- and R-(-)-etodolac (P>>0.05). The Cmax, and AUC0-t of R-(-)-etodolac were markedly higher (P<0.05), while the CL(s) and V/F were markedly lower than those of S-etolodac (P<0.05). CONCLUSION: There is pharmacokinetic difference between S-(+)- and R-(-)- etodolac enantiomers in rats after oral administration.

Effects of flunixin meglumine or etodolac treatment on mucosal recovery of equine jejunum after ischemia.

OBJECTIVE: To examine the effects of flunixin meglumine and etodolac treatment on recovery of ischemic-injured equine jejunal mucosa after 18 hours of reperfusion. ANIMALS: 24 horses. PROCEDURE: Jejunum was exposed to 2 hours of ischemia during anesthesia. Horses received saline (0.9% NaCl) solution (12 mL, i.v., q 12 h), flunixin meglumine (1.1 mg/kg, i.v., q 12 h), or etodolac (23 mg/kg, i.v., q 12 h). Tissue specimens were obtained from ischemic-injured and nonischemic jejunum immediately after ischemia and 18 hours after recovery from ischemia. Transepithelial electric resistance (TER) and transepithelial flux of tritium-labeled mannitol measured mucosal permeability. Denuded villous surface area and mean epithelial neutrophil count per mm2 were calculated. Western blot analysis for cyclooxygenase (COX)-1 and -2 was performed. Pharmacokinetics of flunixin and etodolac and eicosanoid concentrations were determined. RESULTS: Ischemic-injured tissue from horses treated with flunixin and etodolac had significantly lower TER and increased permeability to mannitol, compared with that from horses treated with saline solution. Epithelial denudation after ischemia and 18 hours after recovery was not significantly different among treatments. Both COX-1 and -2 were expressed in ischemic-injured and nonischemic tissues. Ischemia caused significant upregulation of both COX isoforms. Eicosanoid concentrations were significantly lower in tissues from flunixin and etodolac-treated horses, compared with that from horses treated with saline solution. CONCLUSIONS AND CLINICAL RELEVANCE: Flunixin and etodolac treatment retarded recovery of intestinal barrier function in jejunal mucosa after 18 hours of reperfusion, whereas tissues from horses treated with saline solution recovered baseline values of TER and permeability to mannitol.

Oral etodolac, a COX-2 inhibitor, reduces postoperative pain immediately after fast-track cardiac surgery.

PURPOSE: The present study was designed to evaluate the efficacy of a cyclooxygenase (COX)-2 inhibitor, etodolac, on postoperative pain after fast-track cardiac surgery, and to examine the changes in plasma etodolac concentration after oral administration. METHODS: Thirty patients scheduled for elective coronary artery bypass grafting (CABG) surgery were randomly assigned preoperatively in a double-blind fashion to receive either vehicle ( n = 15) or etodolac 400 mg ( n = 15) via a gastric tube at the end of the surgery. Standardized fast-track cardiac anesthesia was used. In both groups, postoperative pain was treated with buprenorphine suppository. Visual analogue pain scores (VASs) were recorded immediately after extubation and at 24 h after surgery. Plasma etodolac concentration was measured at 1, 2, and 6 h after administration ( n = 8). RESULTS: No difference was detected in time to extubation between the etodolac group (209 +/- 85 min, mean +/- SD) and the vehicle group (207 +/- 98 min). VASs were significantly lower in the etodolac (2.3 +/- 2.1) vs the vehicle group (5.8 +/- 2.0) immediately after extubation ( P = 0.009), but no difference was detected in pain scores at 24 h after surgery, or in the amount of buprenorphine administered in the intensive care unit (ICU), or in the incidence of side effects. Plasma etodolac concentration was within the pharmaceutically recommended range at 1 h, 2 h, and 6 h after administration. CONCLUSION: The oral use of etodolac with rectal buprenorphine reduces pain scores immediately after cardiac surgery without an increase in side effects.