Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry

A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r(2)=0.998) in the range of 3.0-85.0 μg L(-1) with a detection limit of 0.7 μg L(-1) for preconcentration of 25.0 mL of the sample and the relative standard deviation (n=6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments.

A comparative study of the novel spectrophotometric methods versus conventional ones for the simultaneous determination of Esomeprazole magnesium trihydrate and Naproxen in their binary mixture

Two novel simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed and validated for simultaneous determination of Esomeprazole magnesium trihydrate (ESO) and Naproxen (NAP) namely; absorbance subtraction and ratio difference. The results were compared to that of the conventional spectrophotometric methods namely; dual wavelength and isoabsorptive point coupled with first derivative of ratio spectra and derivative ratio. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of ESO and NAP in their laboratory prepared mixtures and pharmaceutical preparation. No preliminary separation steps are required for the proposed spectrophotometeric procedures. The statistical comparison showed that there is no significant difference between the proposed methods and the reported method with respect to both accuracy and precision.

Anti-inflammatory activity of copao (Eulychnia acida Phil., Cactaceae) fruits

Copao (Eulychnia acida Phil., Cactaceae) is an endemic species occurring in northern Chile. The edible fruits of this plant are valued for its acidic and refreshing taste. Phenolic-enriched extracts from copao fruit pulp and epicarp, collected in the Elqui and Limari river valleys, were assessed by its in vitro ability to inhibit the pro-inflammatory enzymes lipoxygenase (LOX) and cyclooxygenases (COX-1 and COX-2). At 100 μg/mL, pulp extracts showed better effect towards LOX than epicarp extract, while COX-2 inhibition was observed for both epicarp and pulp samples. In general, the extracts were inactive towards COX-1. A positive correlation was observed between the anti-inflammatory activity and the main phenolic compounds found in this fruit. Copao fruits from the Limari valley, a main place of collection and commercialization, showed major activity, adding evidence on the possible health-beneficial effects of this native Chilean fruit.

Antioxidant and anti-inflammatory assays confirm bioactive compounds in Ajwa date fruit

Ajwa, a variety of date palm Phoenix dactylifera L., produces the most expensive date fruits. Percentages of seed, moisture, fructose, glucose, soluble protein, and fiber in Ajwa dates were 13.24, 6.21, 39.06, 26.35, 1.33, and 11.01, respectively. The ethyl acetate, methanolic, and water extracts of Ajwa dates, active at 250 μg/mL in the MTT assay, inhibited lipid peroxidation (LPO) by 88, 70, and 91% at 250 μg/mL and cyclooxygenase enzymes COX-1 by 30, 31, and 32% and COX-2 by 59, 48, and 45% at 100 μg/mL, respectively. Bioactivity-guided purifications afforded compounds 1-7, in addition to phthalates and fatty acids. Compounds 1-3 showed activity at 100 μg/mL in the MTT assay; inhibited COX-1 enzyme by 59, 48, amd 50% and COX-2 enzyme by 60, 40, amd 39% at 50 μg/mL; and inhibited LPO by 95, 58, amd 66% at 100 μg/mL, respectively. The soluble protein fraction was also very active in both antioxidant and anti-inflammatory assays.

TLC determination of meloxicam in tablets and after acidic and alkaline hydrolysis

A simple and rapid method for separation and determination of meloxicam and its degradation products by thin-layer chromatography with densitometric detection in pharmaceutical preparations was described. The method employed TLC F254 plates as the stationary phase. The solvent system consisted of ethyl acetate : toluene : butylamine (2:2:1, v/v/v). Densitometric analysis was carried out in absorbance mode at wavelength of 297 nm. The method was validated for linearity, precision and accuracy. The limits of detection and determination were 0.96 μg per spot and 2.90 μg per spot, respectively. The drug was degraded in acidic and basic environment, at different temperatures. The degradation products were well resolved from the active substance. The HPLC-MS/MS method for the identification of degradation products of meloxicam (i.e. 5-methylthiazol- 2-ylamine and 5-(dioxide-l(6)-sulfanylidene)-6-methylidenecyclohexa-1,3-diene) was investigated. Because the presented method allows the efficient separation of the drug from some of its degradation products, so it can be used as a stability-indicating analysis.

Spherical harmonics coefficients for ligand-based virtual screening of cyclooxygenase inhibitors

BACKGROUND

Molecular descriptors are essential for many applications in computational chemistry, such as ligand-based similarity searching. Spherical harmonics have previously been suggested as comprehensive descriptors of molecular structure and properties. We investigate a spherical harmonics descriptor for shape-based virtual screening.

METHODOLOGY/PRINCIPAL FINDINGS

We introduce and validate a partially rotation-invariant three-dimensional molecular shape descriptor based on the norm of spherical harmonics expansion coefficients. Using this molecular representation, we parameterize molecular surfaces, i.e., isosurfaces of spatial molecular property distributions. We validate the shape descriptor in a comprehensive retrospective virtual screening experiment. In a prospective study, we virtually screen a large compound library for cyclooxygenase inhibitors, using a self-organizing map as a pre-filter and the shape descriptor for candidate prioritization.

CONCLUSIONS/SIGNIFICANCE

12 compounds were tested in vitro for direct enzyme inhibition and in a whole blood assay. Active compounds containing a triazole scaffold were identified as direct cyclooxygenase-1 inhibitors. This outcome corroborates the usefulness of spherical harmonics for representation of molecular shape in virtual screening of large compound collections. The combination of pharmacophore and shape-based filtering of screening candidates proved to be a straightforward approach to finding novel bioactive chemotypes with minimal experimental effort.

Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest complaints, arthritis, rheumatism, venereal diseases and distemper in dogs.

AIMS OF THE STUDY

To investigate the antioxidant, anti-inflammatory and anti-tyrosinase activities of four Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus latifolius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out.

MATERIALS AND METHODS

DPPH, FRAP and β-carotene-linoleic acid assays were used to determine the antioxidant/radical scavenging activities of these species. Anti-inflammatory activity of these species was assayed against two cyclooxygenase enzymes (COX-1 and COX-2). Tyrosinase inhibition activity was analysed using the modified dopachrome method with l-DOPA as the substrate. Phenolics were quantitatively determined using spectrophotometric methods.

RESULTS

Stems of Podocarpus latifolius exhibited the lowest EC(50) (0.84 μg/ml) inhibition against DPPH. The percentage antioxidant activity based on the bleaching rate of β-carotene ranged from 96% to 99%. High ferric reducing power was observed in all the extracts. For COX-1, the lowest EC(50) value was exhibited by stem extracts of Podocarpus elongatus (5.02 μg/ml) and leaf extract of Podocarpus latifolius showed the lowest EC(50) against COX-2 (5.13 μg/ml). All extracts inhibited tyrosinase activity in a dose-dependent manner with stem extract of Podocarpus elongatus being the most potent with an EC(50) value of 0.14 mg/ml. The total phenolic content ranged from 2.38 to 6.94 mg of GAE/g dry sample.

CONCLUSION

The significant pharmacological activities observed support the use of these species in traditional medicine and may also be candidates in the search for modern pharmaceuticals in medicine, food and cosmetic industries.

In vitro cyclooxygenase inhibition assay for evaluating ecotoxicity of the surface water and domestic wastewater in the Tone Canal, Japan

Cyclooxygenase (COX) plays an important role in eicosanoid metabolism. Nonsteroidal anti-inflammatory drugs (NSAIDs) function as COX inhibitors and are frequently detected in the aquatic environment. Here, we measured the in vitro COX-inhibiting activity of the surface water and domestic wastewater in the Tone Canal, Japan. The concentrations of several NSAIDs in the some samples were also determined using gas chromatography-tandem mass spectrometry for confirming the validity of the assay. The target compounds were extracted from the samples using a solid-phase extraction cartridge. A dose-response relationship between the inhibiting activity and sample volume were observed in the wastewater sample. The higher COX-inhibiting activities were observed in the wastewater sample, as compared with the samples of the surface water in the canal. These inhibiting activities reflected the trends of NSAIDs distribution in the canal. However, the inhibiting activities of the water samples could not be entirely explained by the NSAIDs that were selected for instrumental analysis in this study. Other compounds that were not measured by instrumental analysis in this study might contribute to the inhibiting activities. Therefore, the COX-inhibiting assay would be effective for evaluating inclusive ecotoxicity in the aquatic environment.

[Turbidimetric determination of tenoxicam using molybdophosphoric acid]

A turbidimetric method was developed for tenoxicam quantification using the complexing reaction with molybdophosphoric acid in hydrochloric acid medium; the complex has a maximum of absorbance at 369 nm.

MATERIALS AND METHOD

The practical working conditions were established. In the 2.5 division by 15.0 microg/mL concentration range of tenoxicam in 1N hydrochloric acid, were added 1 mL of 1% molybdophosphoric acid solution and 1 mL of 0.1% sodium lauryl sulphate. The stability of product was evaluated over 60 minutes. The developed method was validated.

RESULTS

The method showed a good linearity in the range of 2.5 division by 15.0 microg/mL (the correlation coefficient r = 0.9996). The detection limit (LD) was 0.44 microg/mL and the quantification limit (LQ) was 1.47 microg/mL. There were established the precision (RSD = 1.82%) and the accuracy (mean recovery is 100.79% in 97.55 division by BY 04.41% the range).

CONCLUSIONS

The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A(1cm,369nm)(1%) higher than tenoxicam in hydrochloric acid medium A(1cm,354nm)(1%).

A liquid chromatography/tandem mass spectrometry method for detecting UGT-mediated bioactivation of drugs as their N-acetylcysteine adducts in human liver microsomes

The detection of the reactive metabolites of drugs has recently been gaining increasing importance. In vitro trapping studies using trapping agents such as glutathione are usually conducted for the detection of reactive metabolites, especially those of cytochrome P450-mediated metabolism. In order to detect the UDP-glucuronosyltransferase (UGT)-mediated bioactivation of drugs, an in vitro trapping method using N-acetylcysteine (NAC) as a trapping agent followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed in this study. After the test compounds (diclofenac and ketoprofen) had been incubated in human liver microsomes with uridine diphosphoglucuronic acid (UDPGA) and NAC, the NAC adducts formed through their acyl glucuronides were analyzed using LC/MS/MS with electrospray ionization (ESI). The NAC adduct showed a mass shift of 145 units as compared to its parent, and the characteristic ion fragmentations reflected the parent. This is a concise and high-throughput method for evaluating reactive metabolites by UGT-mediated bioactivation.

Anthocyanin content, lipid peroxidation and cyclooxygenase enzyme inhibitory activities of sweet and sour cherries

Cherries contain bioactive anthocyanins that are reported to possess antioxidant, anti-inflammatory, anticancer, antidiabetic and antiobese properties. The present study revealed that red sweet cherries contained cyanidin-3-O-rutinoside as major anthocyanin (>95%). The sweet cherry cultivar "Kordia" (aka "Attika") showed the highest cyanidin-3-O-rutinoside content, 185 mg/100 g fresh weight. The red sweet cherries "Regina" and "Skeena" were similar to "Kordia", yielding cyanidin-3-O-rutinoside at 159 and 134 mg/100 g fresh weight, respectively. The yields of cyanidin-3-O-glucosylrutinoside and cyanidin-3-O-rutinoside were 57 and 19 mg/100 g fresh weight in "Balaton" and 21 and 6.2 mg/100 g fresh weight in "Montmorency", respectively, in addition to minor quantities of cyanidin-3-O-glucoside. The water extracts of "Kordia", "Regina", "Glacier" and "Skeena" sweet cherries gave 89, 80, 80 and 70% of lipid peroxidation (LPO) inhibition, whereas extracts of "Balaton" and "Montmorency" were in the range of 38 to 58% at 250 microg/mL. Methanol and ethyl acetate extracts of the yellow sweet cherry "Rainier" containing beta-carotene, ursolic, coumaric, ferulic and cafeic acids inhibited LPO by 78 and 79%, respectively, at 250 microg/mL. In the cyclooxygenase (COX) enzyme inhibitory assay, the red sweet cherry water extracts inhibited the enzymes by 80 to 95% at 250 microg/mL. However, the methanol and ethyl acetate extracts of "Rainier" and "Gold" were the most active against COX-1 and -2 enzymes. Water extracts of "Balaton" and "Montmorency" inhibited COX-1 and -2 enzymes by 84, and 91 and 77, and 87%, respectively, at 250 microg/mL.

Lipid peroxidation and cyclooxygenase enzyme inhibitory activities of acidic aqueous extracts of some dietary supplements

The botanical supplement market is growing at a fast pace with more and more people resorting to them for maintaining good health. Echinacea, garlic, ginkgo, ginseng, Siberian ginseng, grape seed extract, kava kava, saw palmetto and St John's wort are some of the popular supplements used for a variety of health benefits. These supplements are associated with various product claims, which suggest that they possess cyclooxygenase (COX) enzyme and lipid s inhibitory activities. COX enzymes are found to be at elevated levels in inflamed and cancerous cells. To test some of the product claims, selected supplements were analysed for their ability to inhibit COX-1 and -2 enzymes and lipid peroxidation in vitro. The supplements were extracted with acidified water (pH 2) at 37 degrees C to simulate the gastric environment. The supplements tested demonstrated varying degrees of COX enzyme inhibition (5-85% for COX-1 and 13-28% for COX-2). Interestingly, extracts of garlic (Meijer), ginkgo (Solaray), ginseng (Nature's Way), Siberian ginseng (GNC, Nutrilite, Solaray, Natrol), kava kava (GNC, Sundown, Solaray) and St John's wort (Nutrilite) selectively inhibited COX-2 enzyme. These supplements also inhibited lipid peroxidation in vitro (5-99%). The results indicated that the consumption of these botanical supplements studied possess health benefits.

Chronic administration of nonsteroidal-antiinflammatory drugs (NSAIDS): effects upon mouse reproductive functions

Although nonsteroidal-antiinflamatory drugs (NSAIDs) are widely employed, reproductive side effects of prostaglandins long-term inhibition remain unknown. The objective of the present study was to evaluate the effects of chronic low/moderate NSAIDs doses upon mice reproductive functions. Male or female mice were injected (i.p. for 60 or 35 days respectively) with: ibuprofen doses A, B or C (0.56, 1.12 or 1.68 mg/100 g/day respectively) or piroxicam doses A, B or C (0.028, 0.056 or 0.084 mg/100 g/day respectively). Parameters evaluated were: a) in females, spontaneous and induced ovulation, oocyte maturity and spermatozoa migration through genital tract, b) in males, epididymal spermatozoa concentration, motility, viability, resistance to hypoosmotic shock, acrosomal status and membrane maturity and c) in both genders, in vitro and in vivo fertilization, reproductive hormones plasma levels and cyclooxigenase inhibition in reproductive tissues. In females ibuprofen (dose A) elicited a significant reduction in spontaneous and induced ovulation rates and piroxicam (dose A) diminished the concentration of spermatozoa found in the uterus after mating. Males treated with ibuprofen (dose B) showed a reduction in the in vitro fertilization ability. Our data reveal that chronic administration of ibuprofen or piroxicam can exert detrimental effects upon reproductive physiology, which depends on the doses and/or the drug employed.

Spectrofluorometric determination of ketorolac tromethamine via its oxidation with cerium(IV) in pharmaceutical preparations and biological fluids

A simple and sensitive fluorometric method for determination of ketorolac tromethamine was studied. The method depends on oxidation of the drug with cerium(IV) and subsequent monitoring of the fluorescence of the induced cerium(III) at lambda(em) 365 nm after excitation at 255 nm. Different variables affecting the reaction conditions, such as the concentrations of cerium(IV), sulfuric acid concentration, reaction time, and temperature, were carefully studied and optimized. Under the optimum conditions, a linear relationship was found between the relative fluorescence intensity and the concentration of the investigated drug in the range of 0.1-0.8 microg/mL. No interferences could be observed from the excipients commonly present in dosage forms. The proposed method was successfully applied to the analysis of the investigated drug in its pure form, pharmaceutical preparations, and biological fluids with good accuracy and precision. The recoveries for pharmaceutical formulations ranged from 99.8-101.0 +/- 0.6% for tablets, 98.5-101.0 +/- 1.0% for ampoules, and 99.0-100.5 +/- 0.7% for eye drops. The results obtained by the proposed method were satisfactory compared with those obtained by the official method. The recoveries for biological fluids were 99.1-100.4 +/- 0.7 and 99.0-100.0 +/- 0.5% for plasma and urine, respectively.

Liquid-chromatographic separation and determination of process-related impurities, including a regio-specific isomer of celecoxib on reversed-phase C18 column dynamically coated with hexamethyldisilazane

A simple and rapid reversed-phase high-performance liquid-chromatographic method for the separation and determination of process-related impurities of celecoxib (CXB) in bulk drugs and pharmaceuticals was developed. The separation of impurities viz., 4-methylacetophenone (I), 1-(4-methylphenyl)-4,4,4-trifluorobutane-1,3-dione (II), 4-hydrazinobenzene sulfonamide (III) and a regio-specific isomer [3-(4-methylphenyl)-5-trifluoromethyl-1H-pyrazole-1-yl]-benzenesulfonamide (IV), was accomplished on an Inertsil ODS-3 column dynamically coated with 0.1% hexamethyldisilazane (HMDS) in acetonitrile:water (55:45 v/v) as a mobile phase and detection at 242 nm using PDA at ambient temperature. The chromatographic conditions were optimized by studying the effects of HMDS, an organic modifier, time of silanization and column temperature. The method was validated and found to be suitable not only for monitoring the synthetic reactions, but also to evaluate the quality of CXB.

[Nimesulide spectrophotometric determination in the visible region]

Nimesulide is a nonsteroidal antiinflammatory (NSAID) drug whose mechanism of action is characterized by selective inhibition of cyclooxygenase-2. Nimesulide have analgesic and antipyretic properties.

MATERIALS AND METHOD

For nimesulide analysis we developed a spectrophotometric method based on reduction of the nitro group of nimesulide by zinc and hydrochloric acid followed by diazotization and coupling with thymol (5-methyl-2-(1-methylethyl) phenol) in ammonia medium to form a stable chromophore which absorbs at 476 nm. There were established the practical working conditions. The developed method was validated.

RESULTS

The method showed a good linearity in the range of 5 - 40 microg / sample (the correlation coefficient r = 0.9990). The detection limit (LD) was 0.99 microg/sample and the quantification limit (LQ) was 3.32 microg/sample. There were established the system precision (RSD = 1.70%), the precision (RSD < 2.2%) and the accuracy (recovery in the range 97.66 - 102.69% with a mean recovery of 99.81%) of the method.

CONCLUSIONS

A new method for nimesulide spectrophotometric quantification in visible has been developed.

Validated high-throughput HPLC assay for nimesulide using a short monolithic column

High samples analysis rate is a key demand in modern pharmaceutical analysis, especially during new product development and validation of industrial-scale manufacturing process. The present study reports a validated HPLC assay for the dissolution studies of nimesulide-containing tablets (Lizepat 100 mg/tab, Cosmopharm Ltd., Korinthos, Greece). Using a 50 mm x 4.6 mm i.d. monolithic column (Chromolith, Merck) and acetonitrile-phosphate buffer (pH 7.0; 10 mM) (34:66, v/v) as the mobile phase, the separation cycle was completed in 60s at a flow rate of 4.0 ml min(-1). The assay was validated in terms of selectivity against potential impurities of the active ingredient, detection and quantification limits, linearity, accuracy and inter-/intra-day precision. Results from the application of the HPLC method to the accelerated and long-term dissolution stability control of Lizepat tablets (Lot 005) are reported.

An ELISA method to measure inhibition of the COX enzymes

The cyclooxygenase (COX) reaction can be monitored by measurement of oxygen consumption, peroxidase co-substrate oxidation or prostaglandin (PG) detection. This protocol describes a procedure measuring cyclooxygenase activity by quantifying PGE2 produced by enzymatic conversion of arachidonic acid, in the presence or absence of potential inhibitors. This high-throughput method has the advantage that it directly measures cyclooxygenase activity and requires little enzyme. The first part of the assay consists of incubating arachidonic acid, cyclooxygenase and the test samples to generate prostaglandins. The second part uses an ELISA method to quantify the amount of PGE2 produced by the enzymatic reaction. The isolation of COX-1 and COX-2 enzymes is also described. This protocol can be completed in approximately 23 h, including 16-h and 4-h incubation phases. This does not include enzyme preparation (3 h for COX-1 and 24 h for COX-2) or preparation of ELISA plates (23 h, including incubation).

Validation of liquid chromatography and liquid chromatography/tandem mass spectrometry methods for the determination of etoricoxib in pharmaceutical formulations

Reversed-phase liquid chromatography (LC) and LC/tandem mass spectrometry (LC/MS/MS) methods were developed and validated for the determination of etoricoxib in pharmaceutical dosage forms. The LC method was performed by reversed-phase chromatography on a Synergi fusion C18 column (150 x 4.6 mm id) maintained at ambient temperature. The mobile phase consisted of 0.01 M phosphoric acid, pH 3.0-acetonitrile (62 + 38, v/v) at a flow rate of 1.0 mL/min, and photodiode array detection at 234 nm was used. The chromatographic separation was obtained within 7.0 min, and calibration curves were linear in the concentration range of 0.02-150 microg/mL. The LC/MS/MS method was performed on a Luna C18 column (50 x 3.0 mm id). The mobile phase consisted of acetonitrile-water (95 + 5)-0.1% acetic acid (90 + 10, v/v). Detection was performed by positive electrospray ionization in the multiple reaction monitoring mode, monitoring the transitions 359.3 > 280.0 and 332.0 > 95.0 for etoricoxib and piroxicam (internal standard), respectively. The chromatographic separation was obtained within 2.0 min, and calibration curves were linear in the concentration range of 1-5000 ng/mL. Validation parameters, such as specificity, linearity, precision, accuracy, and robustness, were evaluated, which gave results within the acceptable range for both methods. Moreover, the proposed methods were successfully applied for routine quality control analysis of pharmaceutical products and showed significant correlation (r = 0.9999) of the results.

Quantification of infant exposure to celecoxib through breast milk

AIMS

To determine the milk-to-plasma (M/P) concentration ratio of celecoxib, and estimate likely infant exposure.

METHODS

Blood and milk were sampled for 48 h after oral administration of celecoxib 200 mg to six lactating volunteers. The M/P ratio was derived from the area under the concentration-time curves (0-infinity) and the infant 'dose' estimated from celecoxib concentrations in milk.

RESULTS

The median (range) M/P ratio was 0.18 (0.15-0.26). The median (range) infant 'dose' was 0.23% (0.17-0.30%) of the maternal dose, adjusted for weight.

CONCLUSION

The relative 'dose' of celecoxib to which infants are exposed via milk is very low, suggesting that breastfeeding during routine dosing would pose minimal risk.

A new stability--indicating RP-HPLC method to determine assay and known impurity of Celecoxib API

A simple, rapid and accurate Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) method was developed to determine assay and known impurity of Celecoxib API. The chromatographic separation was performed on reversed-phase C-18 column. Eluents were monitored on photo-diode array detector at a wavelength of 254 nm using a mixture (40:60) of buffer and acetonitrile. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for forced-degradation study, linearity and range, accuracy, precision, stability of analytical solutions, and selectivity. Due to its simplicity, rapid, and accuracy, we believe that the method will be useful to determine assay and known impurity of Celecoxib.

Mixture design in the optimization of a microemulsion system for the electrokinetic chromatographic determination of ketorolac and its impurities: Method development and validation

Microemulsion EKC (MEEKC) was used for the determination of ketorolac and its three impurities. The microemulsion system was optimized, for the first time in the literature, using a multivariate strategy involving a mixture design. A 13-run experimental plan covering an experimental domain defined by the components aqueous phase (10 mM borate buffer pH 9.2), oil phase (n-heptane) and surfactant/cosurfactant (SDS/n-butanol) was carried out. Good results were obtained with all microemulsions tested considering as responses analysis time and resolution, and according to the desirability function the best microemulsion system was constituted by 90.0% 10 mM borate buffer, 2.0% n-heptane, 8.0% of SDS/n-butanol in 1:2 ratio. Finally, with the aim of reducing analysis time, a response surface study was carried out in the experimental domain defined by the process variables temperature and voltage and the best values were 17 degrees C and -17 kV, respectively. Applying the optimised conditions, a complete resolution among the analytes was obtained in about 3 min using the short-end injection method. The method was validated for both drug substances and drug product and was applied to the quality control of ketorolac in coated tablets. A comparison of MEEKC, MEKC and CEC for assaying ketorolac and its related substances has been made.

QSAR analysis of meclofenamic acid analogues as selective COX-2 inhibitors

The use of quantitative structure-activity relationships, since its advent, has become increasingly helpful in understanding many aspects of biochemical interactions in drug research. This approach was utilized to explain the relationship of structure with biological activity of selective COX-2 inhibitors. The enormity of the COX-2 discovery is reflected in the unprecedented speed at which research laboratories have sought to validate its clinical implications. Presented herein is a series of 21 derivatives of meclofenamic acid with selective COX-2 inhibitory activity. Several statistically significant regression expressions were obtained for both COX-1 and COX-2 inhibition using sequential multiple linear regression analysis method. Two of these models were selected and validated further, which revealed the importance of Kier molecular flexibility index for COX-2 inhibitory activity and the number of hydrogen bond donor atoms for COX-1 inhibitory activity. Additionally, linear correlation of molecular flexibility with COX-1 and COX-2 inhibitory activities revealed that flexibility of molecules at COX-2 active site can improve the selectivity of COX-2 inhibitors.

Determination of rofecoxib in human plasma and breast milk by high-performance liquid chromatographic assay

A rapid and simple HPLC assay was developed for the determination of rofecoxib in human plasma and breast milk. After solid-phase extraction, rofecoxib was resolved on a C18 column and detected by UV detection at 272 nm. Standard curves were linear over the concentration range 10-2000 microg/L (r2 >0.99). Intra- and inter-day coefficients of variation for both matrices were <10% and the limit of quantification was around 10 microg/L.

Cyclooxygenase 2 expression in the spared nerve injury model of neuropathic pain

Cyclooxygenase-2 (COX-2) after induction peripherally, and within the CNS, plays an important role in producing inflammatory pain. However, its role in neuropathic pain models is controversial. Recently a robust and persistent model of partial nerve injury pain, the spared nerve injury (SNI) model, has been developed. The aim of the present study was to examine the regulation of COX-2 in the rat SNI model and to evaluate the effectiveness of the selective COX-2 inhibitor rofecoxib in preventing neuropathic allodynia and hyperalgesia. RNase protection assays revealed only a very small and transient increase in COX-2 mRNA in the dorsal horn of the spinal cord in the SNI model with a maximum change at 24 h. Immunohistochemical analysis showed a small increase in COX-2 protein in the deep layers of the dorsal horn 10 h following SNI surgery. Rofecoxib (100 microM) did not affect spontaneous excitatory postsynaptic currents or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propanoic acid (AMPA) and N-methyl-d-aspartate (NMDA) responses in lamina II neurons from spinal cords of animals with SNI indicating no detectable action on transmitter release or postsynaptic activity. Furthermore, rofecoxib treatment (1 and 3.2 mg/kg for 5 and 3 days respectively starting on the day of surgery) failed to modify the development of allodynia and hyperalgesia in the SNI model. However, rofecoxib significantly reduced inflammatory hypersensitivity evoked by injection of complete Freund's adjuvant into one hindpaw, indicating that the doses used were pharmacologically active. The pain hypersensitivity produced by the SNI model is not COX-2-dependent.

Comparison of derivative spectrophotometric and liquid chromatographic methods for the determination of rofecoxib

Two different UV spectrophotometric methods were developed for the determination of rofecoxib in bulk form and in pharmaceutical formulations. The first method, an UV spectrophotometric procedure, was based on the linear relationship between the rofecoxib concentration and the lambdamax amplitude at 279 nm. The second one, the first derivative spectrophotometry, was based on the linear relationship between the rofecoxib concentration and the first derivative amplitude at 228, 256 and 308 nm. Calibration curves were linear in the concentration range using peak to zero 1.5-35.0 microg x ml(-1). HPLC was carried out at 225 nm with a partisil 5 ODS (3) column and a mobile phase constituted of acetonitrile and water (50 :50 v/v). A linear range was found to be 0.05-35.0 microg x ml(-1). The developed methods were successfully applied for the assay of pharmaceutical dosage form. The statistics of the analytical data is also presented. The results obtained by first derivative spectrophotometry were compared with HPLC and no significant difference was found.

Reduced incidence of gastroduodenal ulcers associated with lumiracoxib compared with ibuprofen in patients with rheumatoid arthritis

BACKGROUND

Lumiracoxib (Prexige; Novartis Pharma AG, Basel, Switzerland) is a cyclooxygenase-2 selective inhibitor associated with improved gastrointestinal safety compared with nonsteroidal anti-inflammatory drugs, in patients with osteoarthritis.

AIM

To compare the gastroduodenal safety of lumiracoxib with ibuprofen and celecoxib in patients with rheumatoid arthritis.

METHODS

A total of 893 patients with rheumatoid arthritis were randomized to lumiracoxib 400 mg once daily, lumiracoxib 800 mg once daily, ibuprofen 800 mg three times daily or celecoxib 200 mg twice daily for 13 weeks, in a double-blind randomised controlled clinical trial. The primary endpoint was the cumulative incidence of gastroduodenal ulcers over 13 weeks.

RESULTS

The incidence of gastroduodenal ulcers >/=3 mm with lumiracoxib 400 mg once daily (2.8%) or lumiracoxib 800 mg once daily (4.3%) was significantly lower than with ibuprofen (13.6%, all P < 0.01) and not different from celecoxib (1.9%). The incidence of adverse events was similar for lumiracoxib 400, 800 mg and celecoxib (78, 75 and 77%, respectively) and higher with ibuprofen (86%). Discontinuation for adverse events was highest for ibuprofen (12.5% vs. 7.9-8.8% for the other groups).

CONCLUSIONS

Lumiracoxib demonstrated gastroduodenal safety superior to ibuprofen and similar to celecoxib in patients with rheumatoid arthritis.

Collision-induced dissociation of valdecoxib metabolites: a novel rearrangement involving an isoxazole ring

Valdecoxib is a potent COX-2 inhibitor. During metabolism studies of valdecoxib by liquid chromatography/tandem mass spectrometry, we observed a novel mass spectral rearrangement involving an isoxazole ring for some of the metabolites in the negative ion mode. Accurate mass measurements were performed with quadrupole time-of-flight mass spectrometry to determine the elemental compositions of the fragments. Additionally, two types of stable-isotope labeled analogues were prepared to assist with the assignments of these fragments and possible mechanistic rearrangements resulting from collision-induced dissociation (CID). Detailed analyses of the CID mass spectra suggest that the fragmentation process involves a novel two-step rearrangement. The first step consists of an intramolecular SN2 reaction with a five-membered ring rearrangement to form an intermediate. The second step involves a four-membered ring intramolecular rearrangement followed by a cleavage of the N-O bond on the isoxazole ring to form a unique fragment ion at m/z 196. The same phenomenon was observed for a group of structurally related metabolites that also contain a 5-hydroxymethyl or 5-carboxylic acid moieties. A mechanism for the novel rearrangement involving an isoxazole ring is proposed.

Quantitative determination of rofecoxib in pharmaceutical preparations

Rofecoxib was assayed by UV spectrophotometry and HPLC, the concentration ranges were 2-30 microg x ml(-1) and 5-50 microg x ml(-1), respectively. The results, obtained by the two methods in pharmaceutical preparations were compared of each other. There were no significant differences between the mean values and the precisions.

Effect of extraction method on the concentrations of selected bioactive compounds in mandarin juice

A mandarin-type citrus fruit, ponkan (Citrus reticulata), was processed by in-line, chopper pulper, and hand-press extractions to investigate the effect of extraction method on the concentrations of bioactive compounds in processed juice. Concentrations of polymethoxylated flavones (tangeretin, nobiletin, and sinensetin) and beta-cryptoxanthin in juice, and inhibitory activities against arachidonate cyclooxygenase and lipoxygenases of the juice extract were analyzed. The juice processed by hand-press extraction contained the largest amounts of nobiletin (3.56 mg/100 mL), tangeretin (4.10 mg/100 mL), and sinensetin (0.13 mg/100 mL). Concentrations of beta-cryptoxanthin were 0.66, 0.59, 0.55, and 0.50 mg/100 mL in chopper pulper, in-line (5/64 in.), in-line (8/64 in.) and hand-press juices, respectively. Both extracts of in-line juices showed greater inhibitory activity toward platelet 12-lipoxygenase than the others. The inhibitory effect of hand-press juice extract on platelet cyclooxygenase activity was remarkable among juice extracts. All juice extracts effectively inhibited polymorphonuclear 5-lipoxygenase activity at nearly the same rate.

RP-HPLC study of the degradation of diclofenac and piroxicam in the presence of hydroxyl radicals

The effect of hydroxyl radical attack on two non-steroidal anti-inflammatory drugs (NSAIDs) was studied in vitro. Diclofenac and piroxicam were analysed by RP-HPLC after reaction with OH* free radicals to detect newly formed oxidation and/or degradation products. OH* free radicals were obtained by means of ferrous sulphate and ascorbic acid mixtures. During the reaction the mixtures were exposed to irradiation by a tungsten lamp to obtain an increased and more reproducible formation of hydroxyl radicals. The chromatographic profiles showed the formation of several new peaks for both diclofenac and piroxicam due to the presence of a number of degradation/oxidation products formed in the presence of OH* radicals.

Optimization of dissolution test precision for a ketoprofen oral extended-release product

An example of application of experimental design methodologies to the set up of dissolution test conditions for a new ketoprofen oral extended-release dosage form is presented. The aim of the work was to find the best experimental conditions, using a USP apparatus 2 (paddle), for maximizing the method precision as degree of repeatability. The considered factors mainly influencing the dissolution test results were pH and volume of dissolution medium, and paddle stirring speed. Two distinct 4-run Plackett-Burman designs were carried out: one at gastric and the other at intestinal pH values. Each run was performed in triplicate in order to calculate the standard deviations of the drug dissolution efficiency at 60 and 120 min, selected as responses to be minimized. Optimum conditions to carry out the dissolution test were: 900 ml volume of dissolution medium and 70 rpm paddle stirring speed for both environments and pH 1 and 5.5, for the gastric and intestinal environment, respectively.

Cyclooxygenase inhibitory and antioxidant compounds from the mycelia of the edible mushroom Grifola frondosa

The bioassay-guided isolation and purification of the hexane extract of the cultured mycelia of Grifola frondosa led to the characterization of a fatty acid fraction and three compounds, ergosterol (1), ergostra-4,6,8(14),22-tetraen-3-one (2), and 1-oleoyl-2-linoleoyl-3-palmitoylglycerol (3). The composition of fatty acid fraction was confirmed as palmitic, oleic, and linoleic acids by GC-MS and by comparison with the retention values of authentic samples. The structures of compounds 1-3 were established by spectroscopic methods. The fatty acid fraction and compounds 1-3 showed cyclooxygenase (COX) enzyme inhibitory and antioxidant activities. The inhibition of COX-1 enzyme by the fatty acid fraction and compounds 1-3 at 250 microg/mL were 98, 37, 55, and 67%, respectively. Similarly, COX-2 enzyme activity was reduced by fatty acid fraction and compounds 1-3 at 250 microg/mL by 99, 37, 70, and 4%, respectively. The inhibitions of liposome peroxidation by the fatty acid fraction and compounds 1 and 2 at 100 microg/mL were 79, 48, and 42%, respectively. This is the first report of compounds 2 and 3 from the cultured mycelia of G. frondosa. The COX inhibitory activities of compounds 1-3 are reported here for the first time.

Constituents in evening primrose oil with radical scavenging, cyclooxygenase, and neutrophil elastase inhibitory activities

Cold-pressed, non-raffinated evening primrose oil was found to contain lipophilic radical scavengers. A highly enriched fraction of these compounds could be obtained from the oil by extraction with aqueous ethanol and subsequent liquid-liquid partitioning with petroleum. LC-DAD-MS analysis revealed that the fraction contained three aromatic compounds with identical UV and ESI-MS spectra. The compounds were isolated by RP-HPLC and their structures established by chemical and spectroscopic means as 3-O-trans-caffeoyl derivatives of betulinic, morolic, and oleanolic acid. The morolic acid derivative was a new compound. The three esters exhibited pronounced radical scavenging activity against the stable 2,2-diphenyl-1-picrylhydrazyl radical and were potent inhibitors of neutrophil elastase and cyclooxygenase-1 and -2 in vitro. Commercial samples of evening primrose oils contained only traces of these lipophilic antioxidants.

Enantioseparation of novel COX-2 anti-inflammatory drugs by capillary electrophoresis using single and dual cyclodextrin systems

A capillary electrophoresis method was developed for the enantioseparation of three novel cyclooxygenase-2 (COX-2) inhibitor drugs (E-6259, E-6036 and E-6087) with anti-inflammatory and analgesic activities using sulfobutyl ether-beta-cyclodextrin (SBE-beta-CD) as a chiral selector. The use of 50 mM sodium tetraborate at pH 9.2 with 30% v/v methanol, containing 7.1 mM SBE-beta-CD, as a background electrolyte (BGE) allowed the complete enantioseparation of the three neutral racemic mixtures (resolution = 2.4, 3.0 and 8.7, respectively) and their corresponding metabolites (oxidation products) in a single run. Migration times were shortened with some loss of enantioresolution by adding 1.75 mM dimethyl-beta-cyclodextrin (DM-beta-CD) to the previous BGE (dual CD system). The reversal of the migration order of E-6259 enantiomers in the dual CD system was also studied. Furthermore, the addition of DM-beta-CD to the BGE introduced a new chemoselectivity in the system that allowed E-6259 to be separated from the structurally similar compound E-6036.

Determination of celecoxib, a COX-2 inhibitor, in pharmaceutical dosage forms by MEKC

A micellar electrokinetic chromatographic (MEKC) method was developed for the quantification of celecoxib, a COX-2 inhibitor in pharmaceutical dosage forms within the total analysis time of 7 min. The method has been validated and proven to be rugged. The quantification was carried out at 35 degrees C and 25 kV, using a 25 mM borate buffer (pH 9.3), 25 mM sodium dodecyl sulphate with an extended light path capillary (48.5 cm x 50 micro I.D., 40 cm to detector). Calibration curves were constructed for celecoxib (0.2-0.6 mg/ml) by the internal standard method with 2-nitro aniline as an internal standard (coefficient of correlation greater than 0.999). The intermediate precision (between day precision) of migration times and peak area ratios of celecoxib to internal standard were 1.44 and 1.58% R.S.D., demonstrates good reproducibility of the method. The method was applied to a commercial celecoxib formulation (Revibra, 100 mg) and the percentage recoveries were ranged from 93.0 to 98.4%.

Determination of celecoxib in pharmaceutical formulations using UV spectrophotometry and liquid chromatography

A new UV spectrophotometric method (UV method) and a reversed phase liquid chromatographic method (LC method) for the quantitative estimation of celecoxib, a selective COX-2 inhibitor, in pure form and in solid dosage form were developed in the present study. The linear regression equations obtained by least square regression method, were Abs=4.949 x 10(-2).Conc. (in microg/ml)+1.110 x 10(-2) for the UV method and Area under the curve=5.340 x 10(1).Conc. (in ng/ml)+3.144 x 10(2) for the LC method, respectively. The detection limit, as per the error propagation theory, was found to be 0.26 microg/ml and 25 ng/ml, respectively, for the UV and LC methods. The developed methods were employed with a high degree of precision and accuracy for the estimation of total drug content in three commercial capsule formulations of celecoxib. The results of analysis were treated statistically, as per International Conference on Harmonisation (ICH) guidelines for validation of analytical procedures, and by recovery studies. The results were found to be accurate, reproducible and free from interference and better than the earlier reported methods.

LC determination of rofecoxib in bulk and pharmaceutical formulations

An isocratic reversed phase-liquid chromatographic (RP-LC) method has been developed for the determination and purity evaluation of rofecoxib in bulk and pharmaceutical dosage forms using photodiode array detection set at 225 nm. The method is simple, rapid and selective. The method is capable of detecting all process intermediates and other related compounds, which may be present at trace levels in finished products. Hence the method is very useful for process monitoring during the production of rofecoxib. Chlorophenyl methyl sulphone has been used as internal standard for the quantitative determination of rofecoxib. The method is linear in the range of 125-500 microg. The precision for inter- and intra-day assay variation of rofecoxib is below 1.6% relative standard deviation (R.S.D.). The accuracy determined as relative mean error (R.M.E.) for the intra-day assay is within +/-2.0%. The drug was extracted from tablets (Vioxx) using acetonitrile. The percentage recoveries from dosage forms were ranged from 98.2 to 102.6.

Enhancement of amniotic cyclooxygenase type 2 activity in women with preterm delivery associated with twins or polyhydramnios

OBJECTIVE

We tested the hypothesis that preterm delivery in women with twins or polyhydramnios is associated with enhanced expression and activity of cyclooxygenase type 2 in the amnion.

STUDY DESIGN

We obtained amniotic tissue samples from women undergoing preterm delivery complicated by either twins or polyhydramnios and also from women undergoing preterm cesarean delivery before or after labor. We measured amniotic prostaglandin E2 content and determined cyclooxygenase type 1 and type 2 expressions. We inhibited cyclooxygenase type 1 and type 2 activities with selective inhibitors.

RESULTS

Preterm delivery attributed to twins or polyhydramnios was associated with higher prostaglandin E2 production and enhanced amniotic expression of cyclooxygenase type 2. In contrast, cyclooxygenase type 1 expression was unchanged. Incubation of amniotic samples in vitro with either indomethacin or the selective cyclooxygenase type 2 inhibitor SC-236, but not with the cyclooxygenase type 1 inhibitor SC-560, effectively reduced prostaglandin E2 production.

CONCLUSION

Preterm delivery related to multiple gestation or polyhydramnios was associated with enhanced amniotic expression and activity of cyclooxygenase type 2.

A validated LC method for the quantitative determination of celecoxib in pharmaceutical dosage forms and purity evaluation in bulk drugs

A new reversed-phase, isocratic LC method was developed for the quantitative determination of COX-2 inhibitor celecoxib in bulk drugs and in pharmaceutical dosages. The proposed method is also applicable for the purity evaluation of celecoxib in bulk drugs. 5-Methyl 2-Nitro phenol has been used as internal standard for the quantitative determination of celecoxib. The method has been completely validated and proven to be rugged. The limit of detection (LOD) and limit of quantitation (LOQ) for celecoxib impurities namely, 4-hydrazino benzene sulfonamide (Intermediate I) and 1-(4-methyl phenyl)-4,4.4-trifluro butan-1,3-dione (Intermediate II) were found to be 32.0 and 97 ng. respectively. The active pharmaceutical ingredient was extracted from its finished dosage form (capsule) using methanol. The percentage recoveries ranged from 90.7 to 93.8. The stability studies were performed for celecoxib solution placed on laboratory bench and in refrigerator for hundred days. The samples were found to be stable for the study period.

Gender and pregnancy affect neuropeptide responses of the rabbit Achilles tendon

Tendons such as the Achilles tendon are complex structures that are hypocellular, hypovascular, and hyponeural. The development of pathophysiologic function in this tendon because of overuse is relatively common; however, the mechanisms responsible for the development of paratenonitis and tendinosis remain primarily undefined. To understand better a possible regulatory role for neuropeptides (substance P and calcitonin gene related peptide) known to be present in this tissue, the influence of substance P and calcitonin gene related peptide on messenger ribonucleic acid levels for numerous inflammatory molecules, growth factors, and proteinases and inhibitors have been assessed using a semiquantitative reverse transcription-polymerase chain reaction method and explants of paratenon and Achilles tendon midsubstance tissue from adolescent male and female rabbits and tissue from primigravida females. Most of the significant (p < 0.01) changes observed were at the level of the growth factor transcripts and transcripts for proteinases and inhibitors. Twenty-one significant differences in the responsiveness between tissues from male and female rabbits were observed, and 12 significant differences in responsiveness between virgin females and primigravida rabbits were seen. Differences between paratenon and midsubstance responsiveness to the neuropeptides also were observed within each group of animals. The midsubstance tissue from pregnant animals was hyporesponsive to both neuropeptides. These results indicate that neurotransmitter responsiveness of Achilles tendon tissue differs in a gender specific manner and is influenced by pregnancy associated factors.

An inhibitor of type-1 cyclo-oxygenase in tissues from human pregnancy

BACKGROUND

Previous work has shown that first trimester human decidua contains a protein which directly inhibits the activity of type-1 cyclo-oxygenase (COX-1).

METHODS

Activity assays for cyclo-oxygenase types I and II were developed. Cell cytosol was prepared from a number of different sources: human placenta and decidua (first and third trimester), two placental cell-lines (BeWo and TCL-1), an endometrial stromal cell-line and K562 erythroleukemia cells. The effects of all cytosols on activity of type I cyclo-oxygenase, and of cytosols from BeWo choriocarcinoma and decidual cells on type II enzyme, were tested.

RESULTS

Cytosols from first trimester human placenta, two placental cell-lines, an endometrial stromal cell-line and K562 erythroleukemia cells all inhibited the type I enzyme. The inhibitor protein could not be detected in third trimester human decidual cells after labor, and was present only at very low levels in third trimester decidua prior to the onset of labor. Cytosols from BeWo and decidual cells had no effect on the activity of the type-2 cyclo-oxygenase enzyme.

CONCLUSIONS

The inhibitor of type I cyclo-oxygenase was not specific to pregnancy-related tissues, and may be a general regulator of this enzyme. Lower levels of inhibitor were present at term, but the physiological significance of this is unclear. The cytosolic inhibitor appears to be specific to the type I enzyme.

Improved high-performance liquid chromatographic assay for nimesulide

An improved, validated HPLC assay was developed for the non-steroidal anti-inflammatory agent, nimesulide. In contrast to previous methods, the present assay requires smaller plasma volumes (0.2 ml) and utilizes a commercially available, structurally similar analogue of nimesulide, NS-398. The method involves a liquid-liquid extraction procedure that can be completed within 4 h, followed by reversed-phase HPLC analysis. Briefly, the extraction protocol required toluene extraction of acidified plasma samples, followed by back-extraction of the retained toluene phase with aqueous base. The retained aqueous alkaline phase was concentrated by toluene re-extraction. The retained toluene phase was evaporated to dryness and reconstituted with 100 microl of mobile phase. Extracted samples were injected (50 microl) onto a Shandon Hypersil BDS C18 column (5 microm particle size; 250x4.6 mm) equilibrated with 1.0 ml/min of 68:32 (v/v) methanol-citrate (0.08 M)-phosphate (0.04 M) buffer (pH 3.0) at room temperature, with detection at 240 nm. The chromatographic run time was 12 min with retention times of 5.9 min and 9.1 min for nimesulide and NS-398, respectively. The analytical method was successfully utilized for a pilot pharmacokinetic study.

Spectrofluorimetric quantification of malondialdehyde for evaluation of cyclooxygenase-1/thromboxane synthase inhibition

The in vitro assay developed by Hartmann and Ledergerber (1995) utilizing the spectrofluorimetric quantification of malondialdehyde after reaction with thiobarbituric acid was modified and used for further investigations. The human whole blood was replaced by a platelet suspension of pig blood, and calcium ionophore A23187 was used instead of collagen for inducing the arachidonic acid cascade. The modified assay represents a simple, time and cost saving method for the evaluation of cyclooxygenase-1/thromboxane synthase inhibition. The reproducibility and comparability of results is given. Additional experiments allow classification of selective phospholipase A2, cyclooxygenase-1, and thromboxane synthase inhibitors. Further studies of malondialdehyde formation show that the cyclooxygenase and/or the thromboxane synthase are competitively inhibited by reaction products of the cyclooxygenase pathway by a negative feedback mechanism.

Simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor with HPLC and electrochemical detection

A sensitive and selective bioanalytical method for simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor using reversed-phase HPLC and electrochemical detection is described. Chromatographic separation was achieved by using a Regis SPS 100 RP-8 column (5 microns; 150 x 4.6 mm I.D.). This support is coated with a hydrophilic polyoxyethylenepolymer. It allows protein-containing samples to be injected directly onto the column. The electrochemical detector permit a detection limit of 500 pg diclofenac per ml (daily relative standard deviation 6.3%) and 50 ng oxybuprocaine per ml (daily R.S.D. 2.6%), respectively. Results of administered and measured drug-concentrations in time dependent decrease are presented.

Effect of NSAID administration on tissue levels of immunoreactive prostaglandin E2, leukotriene B4, and (S)-flurbiprofen following extraction of impacted third molars

Post-operative pain and inflammation are frequently managed with non-steroidal anti-inflammatory drugs (NSAIDs). Despite the prevalence of their use, however, relatively little is known about in vivo tissue concentrations of inflammatory mediators at the site of tissue injury and their modulation by NSAIDs. This study compares the effect of oral administration of the NSAID flurbiprofen, to placebo, on tissue levels of immunoreactive prostaglandin E2 (iPGE2), leukotriene B4 (iLTB4), and (S)-flurbiprofen within the surgical wound using implanted microdialysis probes in the dental impaction pain model. Twenty-four healthy patients in need of extraction of partial to complete bony mandibular third molars were recruited for this randomized, double-blind, placebo-controlled study. Following pre-operative administration of N2O/O2, midazolam i.v., and regional block anesthesia with 3% mepivacaine, each patient underwent surgical removal of their impacted third molars. Immediately following completion of the surgery, two semi-permeable microdialysis probes (3 kDa molecular weight cut-off) were implanted into each mandibular surgical site. Patients were taken to a recovery room and microdialysis samples and patient pain reports (visual analog scale, VAS) were collected at 30 min intervals for 4 h. Patients randomly received either flurbiprofen (200 mg orally) or placebo at the onset of post-operative pain. Dialysate samples were collected, frozen, and later assayed for iPGE2, iLTB4, and (S)-flurbiprofen levels. Results of this study show that flurbiprofen decreased post-operative pain by approximately 70% compared to placebo-treated patients (P < 0.001). During the 4 h post-operative timecourse of this study, flurbiprofen treatment significantly reduced peak tissue levels of iPGE2 (9.2 +/- 2.6 vs. 0.4 +/- 0.15 nM; P < 0.001), without having a significant effect on peak tissue levels of iLTB4 (2.5 +/- 1.4 vs. 1.49 +/- 0.86 nM) compared to placebo treatment. Levels of (S)-flurbiprofen significantly increased within the surgical wound exceeding therapeutic levels by 60 min after administration. Flurbiprofen is able to significantly suppress the local production of iPGE2 and provide significant analgesic efficacy without altering iLTB4 tissue levels in this model of acute post-operative inflammatory pain. These data indicate that NSAIDs selectively alter eicosanoid levels within surgical wound and evoke analgesia at time points coincident with elevated wound levels of the drug. The combined use of microdialysis probes in awake patients who provide simultaneous pain reports may offer insight into peripheral mechanisms of inflammatory mediator release and pain.

Inhibition of macrophage nitric-oxide production and Ia-expression by docosahexaenoic acid, a constituent of fetal and neonatal serum

PROBLEM

We previously demonstrated profound inhibition of macrophage activation in the murine placenta in vivo. Given the importance of macrophages both in initiating cellular immunity by presenting antigen in the context of Ia to CD4+ T cells, and in killing cellular targets by producing nitric oxide (NO), inhibition of macrophage functions in the placenta may account for the increased susceptibility of the placenta to infection. We have also showed that docosahexaenoic acid (DHA), at concentrations present in the fetal circulation, has a major role in inhibiting macrophage Ia-expression and NO production in the placenta. The concentration of DHA in fetal serum perfusing the placenta is 50x higher than in the adult. DHA has previously been reported to profoundly affect prostanoid production, to be metabolized by lipoxygenases, and to affect lipoxygenases. We now determine if these activities of DHA account for its inhibition of macrophage NO production and Ia-expression.

METHODS

Murine macrophages were cultured in vitro, exposed to IFN gamma endotoxin, DHA, and various eicosanoids, and their ability to produce NO or express Ia determined.

RESULTS

Although the cyclooxygenase inhibitor, indomethacin, did inhibit NO production, DHA inhibited by a different mechanism. DHA further inhibited NO production by macrophages exposed to doses of indomethacin known to maximally inhibit prostanoid production. Stable, biologically active prostanoids did not reverse the inhibitory effect of DHA. Although DHA is metabolized by lipoxygenases, the lipoxygenase inhibitor NDGA did not reverse the inhibition of either NO production nor Ia expression. This indicates that lipoxygenase products of DHA did not mediate inhibition. NDGA itself inhibited NO production and Ia expression. However, DHA did not inhibit by inhibiting lipoxygenase activity because DHA further inhibited macrophages exposed to doses of DHA known to maximally inhibit lipoxygenases. Furthermore, stable biologically active analogs of lipoxygenase products did not reverse DHA inhibition. DHA also did not inhibit by preventing PAF production because PAF did not reverse inhibition of NO production.

CONCLUSION

DHA did not inhibit Ia-expression or NO production via its known effects on eicosanoid or PAF metabolism, nor by being metabolized by lipoxygenases.

Rapid, sensitive and direct chiral high-performance liquid chromatographic method for ketoprofen enantiomers

The stereospecific HPLC assays reported for ketoprofen (KT) mainly utilize indirect approaches. These assays involve the formation of amide diastereomeric derivatives, which are then separated by chromatography. The advantages of indirect methods include versatility, good sensitivity and cost effectiveness; however, lengthy preparation time is often required. Therefore, we have developed a new direct stereospecific HPLC assay for KT enantiomers to improve preparation time and sensitivity. The KT enantiomers and indomethacin, internal standard (I.S.), were resolved using a Chiralpac AD column attached to 5 cm Supelcosil LC-SI at constant temperature (30 degrees C). The mobile phase consisted of hexane-isopropanol-trifluoroacetic acid (90:10:0.1). Under chromatographic conditions employed R-KT, S-KT and I.S. were eluted at 12, 14 and 16 min, respectively. A linear concentration response relationship was found (0.05-5.0 micrograms/ml of enantiomers) which covered normally observed concentrations in plasma after conventional doses of KT. The minimum quantifiable concentration of the assay was found to be 0.025 or 0.25 microgram/ml based on 1 ml of human or 0.1 ml of rat plasma samples, respectively. This direct HPLC method is suitable for pharmacokinetic studies of KT enantiomers and offers the advantages of shorter sample preparation and run time. This method is at least as sensitive as assays currently in use.

[Anti-inflammatory effect of Urtica dioica folia extract in comparison to caffeic malic acid]

Urtica dioica extract is a traditionary used adjuvant therapeutic in rheumatoid arthritis. The antiphlogistic effects of the urtica dioica folia extract IDS 23 (Extractum Urticae dioicae foliorum) and the main phenolic ingredient caffeic malic acid were tested concerning the inhibitory potential on biosynthesis of arachidonic acid metabolites in vitro. The caffeic malic acid was isolated from Urtica folia extract using gel exclusion- and high performance liquid chromatography and identified by mass spectroscopy and nuclear magnetic resonance. Concerning the 5-lipoxygenase products IDS 23 showed a partial inhibitory effect. The isolated phenolic acid inhibited the synthesis of the leukotriene B4 in a concentration dependent manner. The concentration for halfmaximal inhibition (IC50) was 83 microns/ml in the used assay. IDS 23 showed a strong concentration dependent inhibition of the synthesis of cyclooxygenase derived reactions. The IC50 were 92 micrograms/ml for IDS 23 and 38 micrograms/ml for the caffeic malic acid. Calculating the content in IDS 23 the caffeic malic acid is a possible but not the only active ingredient of the plant extract in the tested assay systems. It is demonstrated that the phenolic component showed a different enzymatic target compared with IDS 23. The antiphlogistic effects observed in vitro may give an explanation for the pharmacological and clinical effects of IDS 23 in therapie of rheumatoid diseases.