Evaluation of the in vitro human skin percutaneous absorption of ketoprofen in topical anhydrous and aqueous gels

BACKGROUND

Ketoprofen is a nonsteroidal anti-inflammatory drug used for the treatment of acute and chronic pain associated with inflammatory conditions. This study aims to evaluate the in vitro percutaneous absorption of ketoprofen 10% formulated in proprietary anhydrous and aqueous gels using the Franz skin finite dose model.

MATERIALS AND METHODS

The anhydrous gel was initially characterized for cytotoxicity using EpiDerm skin tissue model by cell proliferation assay and Western blot analysis. The Ultra Performance Liquid Chromatography method for measuring ketoprofen was validated and the stability of ketoprofen 10% in the anhydrous gel formulation was evaluated at 5°C and 25°C for 181 days. The percutaneous absorption of ketoprofen was determined using donated human skin. The tissue sections were mounted within Franz diffusion cells. A variable finite dose of each ketoprofen formulation in either anhydrous or aqueous gel was applied to the skin sections and receptor solutions were collected at various time points.

RESULTS

Cell proliferation assay showed minimal cell death when EpiDerm skin tissue was exposed to the anhydrous gel for 24 h; the levels of protein markers of cell proliferation were not affected after 17-h exposure. Ketoprofen was stable in the anhydrous gel when stored at 5°C and 25°C. When compounded in the anhydrous and aqueous gels, ketoprofen had mean flux rate of 2.22 and 2.50 μg/cm2 /h, respectively, after 48 h. The drug was distributed to the epidermis and dermis sections of the skin. Both the anhydrous and aqueous gels facilitated the percutaneous absorption of ketoprofen without statistically significant differences.

CONCLUSION

The anhydrous gel can be used as a base to facilitate the transdermal delivery of ketoprofen. Although the anhydrous and aqueous gels can deliver a similar amount of ketoprofen, the anhydrous gel (water activity below 0.6) allows for extended default beyond-use-date of compounding preparations.

Ketoprofen exposure perturbs nitrogen assimilation and ATP synthesis in rice roots: An integrated metabolome and microbiome analysis

Ketoprofen, a commonly used non-steroidal anti-inflammatory drug (NSAID), can enter farmland environments via sewage irrigation and manure application and is toxic to plants. However, there have been relatively few studies on the association of ketoprofen with nitrogen (N) assimilation and metabolic responses in plants. Accordingly, the goal of this study was to investigate the effects of ketoprofen on ATP synthesis and N assimilation in rice roots. The results showed that with increasing ketoprofen concentration, root vitality, respiration rate, ATP content, and H+-ATPase activity decreased and plasma membrane permeability increased. The expressions of OSA9, a family III H+-ATPase gene, and OSA6 and OSA10, family IV genes, were upregulated, indicating a response of the roots to ketoprofen. Nitrate, ammonium, and free amino acids content decreased with increased ketoprofen. The levels of enzymes involved in N metabolism, namely nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthetase, and glutamate dehydrogenase, also decreased under ketoprofen treatment. Principal component analysis revealed that ketoprofen treatment can significantly affect energy synthesis and nitrogen assimilation in rice roots, while these effects can be alleviated by the antioxidant response. Most of the metabolite contents increased, including amino acids, carbohydrates, and secondary metabolites. Key metabolic pathways, namely substance synthesis and energy metabolism, were found to be disrupted. Microbiome analysis showed that community diversity and richness of rice root microorganisms in solution increased with increasing levels of ketoprofen treatment, and the microbial community structure and metabolic pathways significantly changed. The results of this study provides new insights into the response of rice roots to ketoprofen.

Synthesis and Preclinical Evaluation of 18F-Labeled Ketoprofen Methyl Esters for Cyclooxygenase-1 Imaging in Neuroinflammation

Cyclooxygenase (COX) is a rate-limiting enzyme in the synthesis of proinflammatory prostanoids from arachidonic acid. In vivo imaging of COX by PET is a potentially powerful tool for assessing the inflammatory response to injury, infection, and disease. We previously reported on a promising PET probe for COX imaging, ¹¹C-labeled ketoprofen methyl ester, which can detect COX-1 activation in models of neuroinflammation and neurodegenerative disorders. In the current study, we aimed to design a fluorine-substituted benzoyl group of ketoprofen (FKTP) and to evaluate its racemate and enantiomers (¹⁸F-labeled ketoprofen methyl ester, [¹⁸F]FKTP-Me) as PET proradiotracers, potential radiopharmaceuticals for in vivo PET study of COX-1. Methods: We performed nucleophilic aromatic ¹⁸F-fluorination to obtain the desired racemic radiolabeled probe, (RS)-[¹⁸F]FKTP-Me, at a radiochemical yield of 11%-13%. Subsequent high-performance liquid chromatography separation with a chiral column yielded the desired enantiomerically pure (R)- and (S)-[¹⁸F]FKTP-Me. We examined the in vivo properties of (RS)-, (R)-, and (S)-[¹⁸F]FKTP-Me in PET studies using rats in which hemispheric inflammation was induced by intrastriatally injecting a lipopolysaccharide. Results: Racemic (RS)-[¹⁸F]FKTP-Me and enantiomeric (R)- or (S)-[¹⁸F]FKTP-Me were synthesized with radiochemical and chemical purities of more than 99%. The metabolite analysis revealed that the racemic (RS)-[¹⁸F]FKTP-Me crossed the blood-brain barrier and entered the brain, where it was subsequently hydrolyzed to its pharmacologically active acid form. PET images revealed a high accumulation of (R)-, (S)-, and (RS)-[¹⁸F]FKTP in the inflamed regions in rat brain. Moreover, the accumulated radioactivity of (S)-[¹⁸F]FKTP-Me was higher than that of (RS)-[¹⁸F]FKTP-Me and (R)-[¹⁸F]FKTP-Me, which was correlated with the stereospecific inhibitory activity of FKTP against COX-1. Conclusion: From the results of this study, we conclude that racemic (RS)-[¹⁸F]FKTP-Me and its enantiomers could act as proradiotracers of neuroinflammation in rat brain by the association of their hydrolyzed acid forms with COX-1 in inflamed regions. In particular, (S)-[¹⁸F]FKTP-Me demonstrated suitable properties as a COX-1-specific probe in PET imaging of neuroinflammation.

Human Serum Albumin Aggregation/Fibrillation and its Abilities to Drugs Binding

Human serum albumin (HSA) is a protein that transports neutral and acid ligands in the organism. Depending on the environment's pH conditions, HSA can take one of the five isomeric forms that change its conformation. HSA can form aggregates resembling those in vitro formed from amyloid at physiological pH (neutral and acidic). Not surprisingly, the main goal of the research was aggregation/fibrillation of HSA, the study of the physicochemical properties of formed amyloid fibrils using thioflavin T (ThT) and the analysis of ligand binding to aggregated/fibrillated albumin in the presence of dansyl-l-glutamine (dGlu), dansyl-l-proline (dPro), phenylbutazone (Phb) and ketoprofen (Ket). Solutions of human serum albumin, both non-modified and modified, were examined with the use of fluorescence, absorption and circular dichroism (CD) spectroscopy. The experiments conducted allowed observation of changes in the structure of incubated HSA (HSA_INC) in relation to nonmodified HSA (HSA_FR). The formed aggregates/fibrillation differed in structure from HSA monomers and dimers. Based on CD spectroscopy, previously absent βstructural constructs have been registered. Whereas, using fluorescence spectroscopy, the association constants differing for fresh and incubated HSA solutions in the presence of dansyl-amino acids and markers for binding sites were calculated and allowed observation of the conformational changes in HSA molecule.

Mechanisms and quantification of adsorption of three anti-inflammatory pharmaceuticals onto goethite with/without surface-bound organic acids

Nowadays non-steroidal anti-inflammatory drugs (NSAIDs) are often detected in surface water and groundwater. In this study, effects of environmental factors, i.e., solution pH, ionic strength, temperature and surface-bound organic acids, on bonding of three typical NSAIDs (ketoprofen, naproxen and diclofenac) onto goethite were systematically investigated. Column chromatography, batch experiments, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and surface complexation modeling were used to probe the adsorption mechanisms. Bonding of three NSAIDs onto goethite was totally reversible, ionic strength-dependent and endothermic (adsorption enthalpy 2.86-9.75 kJ/mol). These evidences supported H-bonding mechanism, which was further explained by ATR-FTIR observation and a triple planes model. Surface-bound organic acids (phthalic acid, trimellitic acid and pyromellitic acid) by inner-sphere complexation with goethite were hard to be desorbed. Surface-bound phthalic acid increased the uptake of NSAIDs but surface-bound trimellitic acid and pyromellitic acid reduced their adsorption. The reason is that the adsorbed phthalic acid can result in a more hydrophobic surface while adsorbed trimellitic acid and pyromellitic acid increased the surface negative charge and polarity. Finally, adsorption of NSAIDs onto goethite with/without surface-bound organic acids was well described by a free energy model, in which contributions of interactions (e.g., H-bonding and van der Waals) were evaluated.

Long-term exposure of Mytilus galloprovincialis to diclofenac, Ibuprofen and Ketoprofen: Insights into bioavailability, biomarkers and transcriptomic changes

Non-steroidal anti-inflammatory drugs (NSAIDs) represent a growing concern for marine ecosystems due to their ubiquitous occurrence and documented adverse effects on non-target organisms. Despite the remarkable efforts to elucidate bioaccumulation and ecotoxicological potential under short-term conditions, limited and fragmentary information is available for chronic exposures. In this study bioavailability, molecular and cellular effects of diclofenac (DIC), ibuprofen (IBU) and ketoprofen (KET) were investigated in mussels Mytilus galloprovincialis exposed to the realistic environmental concentration of 2.5 μg/L for up to 60 days. Results indicated a significant accumulation of DIC and IBU but without a clear time-dependent trend; on the other hand, KET concentrations were always below the detection limit. Analyses of a large panel of molecular, biochemical and cellular biomarkers highlighted that all investigated NSAIDs caused alterations of immunological parameters, genotoxic effects, modulation of lipid metabolism and changes in cellular turn-over. This study provided the evidence of long-term ecotoxicological potential of NSAIDs, further unraveling the possible hazard for wild marine organisms.

Continuous transformation of chiral pharmaceuticals in enzymatic membrane bioreactors for advanced wastewater treatment

This study demonstrates continuous enantiomeric inversion and further biotransformation of chiral profens including ibuprofen, naproxen and ketoprofen by an enzymatic membrane bioreactor (EMBR) dosed with laccase. The EMBR showed non-enantioselective transformations, with high and consistent transformation of both (R)- and (S)-ibuprofen (93 ± 6%, n = 10), but lower removals of both enantiomers of naproxen (46 ± 16%, n = 10) and ketoprofen (48 ± 17%, n = 10). Enantiomeric analysis revealed a bidirectional but uneven inversion of the profens, for example 14% inversion of (R)- to (S)- compared to 4% from (S)- to (R)-naproxen. With redox-mediator addition, the enzymatic chiral inversion of both (R)- and (S)-profens remained unchanged, although the overall conversion became enantioselective; except for (S)-naproxen, the addition of redox mediator promoted the degradation of (R)-profens only.

Continuous treatment of non-sterile hospital wastewater by Trametes versicolor: How to increase fungal viability by means of operational strategies and pretreatments

Hospital wastewaters have a high load of pharmaceutical active compounds (PhACs). Fungal treatments could be appropriate for source treatment of such effluents but the transition to non-sterile conditions proved to be difficult due to competition with indigenous microorganisms, resulting in very short-duration operations. In this article, coagulation-flocculation and UV-radiation processes were studied as pretreatments to a fungal reactor treating non-sterile hospital wastewater in sequential batch operation and continuous operation modes. The influent was spiked with ibuprofen and ketoprofen, and both compounds were successfully degraded by over 80%. UV pretreatment did not extent the fungal activity after coagulation-flocculation measured as laccase production and pellet integrity. Sequential batch operation did not reduce bacteria competition during fungal treatment. The best strategy was the addition of a coagulation-flocculation pretreatment to a continuous reactor, which led to an operation of 28days without biomass renovation.

Preparation and Characterization of Immobilized Lipase from Pseudomonas Cepacia onto Magnetic Cellulose Nanocrystals

Magnetic cellulose nanocrystals (MCNCs) were prepared and used as an enzyme support for immobilization of Pseudomonas cepacialipase (PCL). PCL was successfully immobilized onto MCNCs (PCL@MCNC) by a precipitation-cross-linking method. The resulting PCL@MCNC with a nanoscale size had high enzyme loading (82.2 mg enzyme/g) and activity recovery (95.9%). Compared with free PCL, PCL@MCNC exhibited significantly enhanced stability and solvent tolerance, due to the increase of enzyme structure rigidity. The observable optimum pH and temperature for PCL@MCNC were higher than those of free PCL. PCL@MCNC manifested relatively higher enzyme-substrate affinity and catalytic efficiency. Moreover, PCL@MCNC was capable of effectively catalyzing asymmetric hydrolysis of ketoprofenethyl ester with high yield of 43.4% and product e.e. of 83.5%. Besides, immobilization allowed PCL@MCNC reuse for at least 6 consecutive cycles retaining over 66% of its initial activity. PCL@MCNC was readily recycled by magnetic forces. Remarkably, the as-prepared nanobiocatalyst PCL@MCNC is promising for biocatalysis.

Effects of non-enzymatic glycation in human serum albumin. Spectroscopic analysis

Human serum albumin (HSA), transporting protein, is exposed during its life to numerous factors that cause its functions become impaired. One of the basic factors --glycation of HSA--occurs in diabetes and may affect HSA-drug binding. Accumulation of advanced glycation end-products (AGEs) leads to diseases e.g. diabetic and non-diabetic cardiovascular diseases, Alzheimer disease, renal disfunction and in normal aging. The aim of the present work was to estimate how non-enzymatic glycation of human serum albumin altered its tertiary structure using fluorescence technique. We compared glycated human serum albumin by glucose (gHSA(GLC)) with HSA glycated by fructose (gHSA(FRC)). We focused on presenting the differences between gHSA(FRC) and nonglycated (HSA) albumin used acrylamide (Ac), potassium iodide (KI) and 2-(p-toluidino)naphthalene-6-sulfonic acid (TNS). Changes of the microenvironment around the tryptophan residue (Trp-214) of non-glycated and glycated proteins was investigated by the red-edge excitation shift method. Effect of glycation on ligand binding was examined by the binding of phenylbutazone (PHB) and ketoprofen (KP), which a primary high affinity binding site in serum albumin is subdomain IIA and IIIA, respectively. At an excitation and an emission wavelength of λex 335nm and λem 420nm, respectively the increase of fluorescence intensity and the blue-shift of maximum fluorescence was observed. It indicates that the glycation products decreases the polarity microenvironment around the fluorophores. Analysis of red-edge excitation shift method showed that the red-shift for gHSA(FRC) is higher than for HSA. Non-enzymatic glycation also caused, that the Trp residue of gHSA(FRC) becomes less accessible for the negatively charged quencher (I(-)), KSV value is smaller for gHSA(FRC) than for HSA. TNS fluorescent measurement demonstrated the decrease of hydrophobicity in the glycated albumin. KSV constants for gHSA-PHB systems are higher than for the unmodified serum albumin, while KSV values for gHSA-KP systems are only slightly lower than that obtained for HSA-KP. The affinity of PHB to the glycated HSA is stronger than to the non-glycated in the first class binding sites within subdomain IIA, in the vicinity of Trp-214. Ketoprofen bound to unmodified human serum albumin stronger than for glycated albumin and one class of binding sites is observed (Scatchard linear plots).

Cysteine amide adduct formation from carboxylic acid drugs via UGT-mediated bioactivation in human liver microsomes

Although chemical trapping has been widely used to evaluate cytochrome P450-mediated drug bioactivation, thus far, only a few in vitro-trapping studies have been performed on UDP-glucuronosyltransferase (UGT)-mediated drug bioactivation. In this study, we used cysteine (Cys) as trapping agent to gain new insights into the UGT-mediated bioactivation involving acyl glucuronides of carboxylic acid drugs. Diclofenac, ketoprofen and ibuprofen were incubated in human liver microsomes with UDPGA and Cys, followed by analysis using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). The N-acyl-Cys amide adduct of diclofenac was characterized by mass analysis and was detectable even in photodiode array analysis. Our data indicated that the formation of such adducts reflects the reactivity of the corresponding acyl glucuronides. In addition, it was suggested that the adduct formation requires an N-terminal Cys moiety with both a free amine and a free thiol group, from the results using various cysteine derivatives. We propose that the S-acyl-Cys thioester adduct can form via transacylation of an acyl glucuronide and can then form to an N-acyl-Cys amide adduct through intramolecular S- to N-acyl rearrangement. This series of the reactions has important implications as a possible bioactivation mechanism for covalent binding of carboxylic acid drugs to macromolecules.

Nanofibers Fabricated Using Triaxial Electrospinning as Zero Order Drug Delivery Systems

A new strategy for creating functional trilayer nanofibers through triaxial electrospinning is demonstrated. Ethyl cellulose (EC) was used as the filament-forming matrix in the outer, middle, and inner working solutions and was combined with varied contents of the model active ingredient ketoprofen (KET) in the three fluids. Triaxial electrospinning was successfully carried out to generate medicated nanofibers. The resultant nanofibers had diameters of 0.74 ± 0.06 μm, linear morphologies, smooth surfaces, and clear trilayer nanostructures. The KET concentration in each layer gradually increased from the outer to the inner layer. In vitro dissolution tests demonstrated that the nanofibers could provide linear release of KET over 20 h. The protocol reported in this study thus provides a facile approach to creating functional nanofibers with sophisticated structural features.

Effect of temperature on removal of trace organic chemicals in managed aquifer recharge systems

This study was undertaken to investigate whether changes in temperature experienced in MAR systems affect attenuation of trace organic chemicals (TOrCs). A set of laboratory-scale soil columns were placed in a temperature-controlled environmental chamber and operated at five different temperature set-points (30, 20, 10, 8 and 4°C) covering the range of typical groundwater temperatures in cold, moderate and arid climate regions. Removal of bulk organic carbon both in the infiltration zone as well as during deeper infiltration was independent of temperature. Of the 22 TOrCs investigated, only six chemicals exhibited changes in attenuation as a function of temperature. Attenuation of four of the compounds (diclofenac, gemfibrozil, ketoprofen and naproxen) decreased as the temperature was reduced from 30°C to 4°C, likely due to decreased microbial activity at lower temperatures. As the temperature was decreased, however, attenuation of oxybenzone and trimethoprim were noted to increase. This increased attenuation was likely due to more efficient sorption at lower temperatures, though possible changes in the microbial composition as the temperature decreased may also have contributed to this change. Changes in rate constants of attenuation (ka) for the biotransformed TOrCs with temperature suggested the existence of a critical temperature at 10°C for three of the four TOrCs, where significant changes to rates of attenuation occurred. Results from this study indicated that for most TOrCs, changes in temperature do not impact their attenuation. Thus, seasonal changes in temperature are not considered to be a major concern for attenuation of most TOrCs in MAR systems.

Ecotoxicity of ketoprofen, diclofenac, atenolol and their photolysis byproducts in zebrafish (Danio rerio)

The occurrence of pharmaceutical compounds in wastewater treatment plants and surface waters has been detected worldwide, constituting a potential risk for aquatic ecosystems. Adult zebrafish, of both sexes, were exposed to three common pharmaceutical compounds (atenolol, ketoprofen and diclofenac) and their UV photolysis by-products over seven days. The results show that diclofenac was removed to concentrations<LOD after 5 min of UV irradiation. The oxidative stress response of zebrafish to pharmaceuticals and their photolysis by-products was evaluated through oxidative stress enzymes (glutathione-S-transferase, catalase, superoxide dismutase) and lipid peroxidation. Results suggest that the photolysis by-products of diclofenac were more toxic than those from the other compounds tested, showing an increase in GST and CAT levels, which are also supported by higher MDA levels. Overall, the toxicity of waters containing atenolol and ketoprofen was reduced after the parent compounds were transformed by photolysis, whereas the toxicity increased significantly from the by-products generated through diclofenac photolysis. Therefore, diclofenac photolysis would possibly necessitate higher irradiation time to ensure that the associated by-products are completely degraded to harmless form(s).

Co-metabolic oxidation of pharmaceutical compounds by a nitrifying bacterial enrichment

The biotransformation of five selected pharmaceuticals ibuprofen (IBP), ketoprofen (KTP), carbamazepine (CBZ), dexamethasone (DXM) and iopromide (IOP) by a stable nitrifying enrichment culture was investigated at concentrations ranging between 25 μg/L and 2mg/L. Complete biotransformation was observed only for IBP and KTP, although, an inverse correlation between transformation rate and concentration was found. The transformation pattern observed is consistent with ammonia monooxygenase (AMO) activity. The metabolic succession of the compounds according to the biotransformation rates was: IBP>KTP>DXM>CBZ>IOP. A linear correlation between the calculated diffusive flux of the model compounds across a bilayer membrane and their biotransformation rates was found. Our results support the concept that augmentation with nitrifying activity can enhance the removal of trace organic pollutants during effluent treatment. Furthermore, ammonia-oxidizing activity appears as a good indicator for estimation of potential of biodegradability of pharmaceuticals, especially at low concentrations.

Preparation and in vitro evaluation of a pluronic lecithin organogel containing ricinoleic acid for transdermal delivery

The present study deals with the preparation and in vitro evaluation of a Pluronic lecithin organogel gel containing ricinoleic acid for transdermal delivery. Blank Pluronic lecithin organogel gels were prepared using ricinoleic acid as the oil phase and characterized for pH, viscosity, gelation temperature, and microscopic structure. The optimized Pluronic lecithin organogel gel formulation was further evaluated using ketoprofen (10%) and dexamethasone (0.5%) as model drugs. The stability and in vitro permeability of ketoprofen and dexamethasone was evaluated and compared with the corresponding control formulation (Pluronic lecithin organogel gel made with isopropyl palmitate as the oil phase). The pH and viscosity of blank Pluronic lecithin organogel gel prepared with ricinoleic acid was comparable with the isopropyl palmitate Pluronic lecithin organogel gel. The thixotropic property of ricinoleic acid Pluronic lecithin organogel gel was found to be better than the control. Drug-loaded Pluronic lecithin organogel gels behaved in a similar manner and all formulations were found to be stable at 25 degrees C, 35 degrees C, and 40 degrees C for up to 35 days. The penetration profile of dexamethasone was similar from both the Pluronic lecithin organogel gels, while the permeability for ketoprofen from Pluronic lecithin organogel gel containing ricinoleic acid was found to be three times higher as compared to the control formulation.

[Biophysical parameters of erythrocyte membranes and mechanisms of interaction with non-opioid analgesics under acute pain syndrome]

Methods of fluorescent probing, spectrophotometry and microcalorimetry were applied to investigate the alterations in biophysical parameters of erythrocytes membranes, and specifically microviscosity, surface charge, molecular organization of lipid bilayer and lipid-protein interactions under conditions of acute pain syndrome produced by experimental chemical lesion. The distinctive features of non-opiod analgesics interactions and binding to the erythrocytes membranes of rats subjected to acute nociceptive pain accompanied with oxidative stress development were investigated. The abilities of analgesics under research, and namely paracetamol, aspirin, phenazone, ketorolac, pyrodazole, ketoprofenum, natrium mefenaminate, indometacin, nimesulide to make up physico-chemical complexes with lipoperoxidation modified erythrocytes surface and protein-lipid bilayer showed marked changes. The significance of oxidative damage of biophase under conditions of acute pain syndrome for analgesics effective pharmacodynamics and pharmacokinetics realization is under consideration.

The role of microbial adaptation and biodegradable dissolved organic carbon on the attenuation of trace organic chemicals during groundwater recharge

It is widely recognized that efficient biological attenuation of bulk organic matter and trace organic chemicals (TOrC) can occur in managed aquifer recharge (MAR) systems receiving reclaimed water. The heterotrophic microbial activity in these subsurface systems is a function of the availability of biodegradable dissolved organic carbon (BDOC) present in reclaimed water. This study examined the influence of environmental factors, such as BDOC-rich (>1.6 mg/L) and BDOC-starving (<1mg/L) conditions and microbial adaptation, on the attenuation of TOrC, including clofibric acid, dichlorprop, gemfibrozil, ibuprofen, ketoprofen, mecoprop, and naproxen, within soil-columns mimicking groundwater recharge. Under conditions that were characterized by a lack of BDOC and a biocommunity that was not yet adapted to these conditions, attenuation of biodegradable TOrC was less than 15%. After a three-month adaptation period, biotransformation increased to more than 80% for the biodegradable TOrC. This suggests that adaptation likely initiates enzyme expressions that eventually results in TOrC transformations even under seemingly less favorable conditions (i.e., lack of biodegradable carbon). For both non-adapted (stressed) and adapted conditions in the presence of higher concentrations of BDOC and travel times of 7 days, the degree of biotransformation was variable across compounds but generally exceeded 25%. This suggests that BDOC above a minimum level (>1.6 mg/L) can provide favorable microbial conditions resulting in TOrC removal, even for non-adapted systems. However, it is noteworthy that adapted MAR systems that were fed with low BDOC levels performed similarly or better with respect to TOrC biotransformation than systems that received BDOC levels above 1.6 mg/L. These findings are important for field-scale applications. They suggest that MAR facilities that are microbiologically active and are fed with highly treated water with effluent concentrations of less than 1 mg/L (i.e., nanofiltration permeate) can still attenuate biodegradable TOrC.

Arginine 485 of human serum albumin interacts with the benzophenone moiety of ketoprofen in the binding pocket of subdomain III A and III B

Arylpropionic acid nonsteroidal anti-inflammatory drusg (NSAIDs) primarily bind to subdomain III A (site II) of human serum albumin (HSA). Ketoprofen (KP), an arylpropionic acid that contains a photoreactive benzophenone moiety, was used to photolabel the binding region of site II. LC/Q-TOF mass spectrometry determination revealed that R485 was the amino acid residue that formed covalent adduct with the benzophenone moiety of KP. Point mutation of arginine 485 to alanine showed a slight decrease in the overall binding percentage of KP when compared to that of native HSA. The induced circular dichroism spectral data of KP with both R485A and native albumin confirmed the photolabeling findings. Interestingly, an increase in the extent of [14C]KP covalent adduct formation with the 11.6 kDa peptide derived from subdomain IIB-IIIA was observed for R485A. In contrast, mutation of arginine 410 caused a significant reduction of binding percentage, confirming the importance of this residue in high affinity binding of arylpropionic acid derivatives. This may indicate that while KP's carboxylate interacts electrostatically with arginine 410, the benzophenone moiety may have swung away from helix 6 in the absence of arginine 485. In this study, photolabeling of native and mutants albumins, R485A and R410C with [14C]KP confirmed that R485 involved in the non-electrostatic interaction with the benzophenone moiety of KP, but not vital to hold KP in the binding pocket of subdomain IIIA.

Biofilm controlled sorption of selected acidic drugs on river sediments characterized by different organic carbon content

The sorption process of selected non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac) on biofilm covered river sediments were investigated in laboratory. In the course of the experiments, the effect of pH of aqueous phase, the effect of TOC (total organic carbon) content of biofilm on the sorption processes were studied. The determination of concentration of drugs was performed by gas chromatography mass spectrometry (GC-MS) both in liquid and solid phases. The pseudo-first-order rate constant of the sorption was found to be 83 min(-1). The effect of pH on the sorption of diclofenac was significantly lower than the obtained values in case of the other three drugs. The calculated K(d) (sorption coefficient) values increased in the sequence of ibuprofen, naproxen, ketoprofen and diclofenac and varied between 0.1-0.4; 0.2-0.7; 0.2-1.2; 0.2-1.4 kg L(-1) respectively, depending on the characteristics of the sediments. The value of K(d)×f(oc) showed a straight line as function of f(oc) (fraction of organic carbon) therefore, instead of the widely distributed normalization process (K(d)/f(oc)), an empirical equation (K(d)=A/f(oc)+B) was suggested for estimation of the K(d) values in case of different TOC content sediments.

Investigation of ketoprofen binding to human serum albumin by spectral methods

The binding of ketoprofen with human serum albumin (HSA) was studied by fluorescence and absorption spectroscopic methods. Quenching of fluorescence of HSA was found to be a static quenching process. At 288.15, 298.15, 308.15 and 318.15 K, the binding constants and binding sites were obtained. The effects of Cu2+, Al3+, Ca2+, Pb2+ and K+ on the binding at 288.15 K were also studied. The thermodynamic parameters, ΔH, ΔG and ΔS were got and the main sort of acting force between ketoprofen and HSA was studied. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r, between the acceptor (ketoprofen) and the donor (HSA) was calculated.

Photoinflammatory responses to UV-irradiated ketoprofen mediated by the induction of ROS generation, enhancement of cyclooxygenase-2 expression, and regulation of multiple signaling pathways

Ketoprofen (KP) is photolabile and undergoes degradation when irradiated by sunlight, causing the development of various skin diseases. In this study, we found that UVB-irradiated KP can lead to inflammatory responses mediated by the induction of COX-2 and production of PGE(2). The ability of cells to repair UVB-induced cyclobutane pyrimidine dimers was impaired by UVB-irradiated KP, which consequently facilitated UVB-induced DNA damage to keratinocytes. The reactive oxygen species (ROS) generated by the photodegradation of KP facilitate UVB-induced inflammation and apoptosis in HaCaT cells. Elevation of the COX-2 levels was inhibited by an NADPH oxidase inhibitor and an NF-kappaB inhibitor but was largely enhanced after glutathione depletion by buthionine sulfoximine. Inhibition of ERK1/2, p38, and PI3K signaling attenuated the induction of COX-2, whereas inhibition of JNK signaling by SP600125 had very little effect. UVB-irradiated KP provoked an appreciable accumulation of pSer(15)-p53/COX-2 complexes, but this nuclear association of complexes was partially inhibited by PD98059. Silencing of COX-2 with siRNA was associated with reduced p53 phosphorylation and enhanced KP-photoinduced loss of mitochondrial membrane potential and cleavage of caspase 3 and PARP. This induction of apoptosis was prevented by N-acetylcysteine. In conclusion, this study highlights the particular inflammatory response to a photooxidative drug and suggests that KP-photoinduced inflammatory responses are predominantly attributable to induction of ROS generation and directly impair DNA repair.

White-rot fungus-mediated degradation of the analgesic ketoprofen and identification of intermediates by HPLC-DAD-MS and NMR

Ketoprofen is a nonsteroidal anti-inflammatory drug that has been detected in the environment in the range of ng L(-1)-microg L(-1) due to its low degradability in some wastewater treatment plants. In this study, the use of the white-rot fungus Trametes versicolor to effectively degrade ketoprofen in a defined liquid medium was assessed. The fungus eliminated ketoprofen to nondetectable levels in 24h when it was added at 10mgL(-1) whereas at low concentration of 40microgL(-1) it was almost completely removed (95%) after 5h. Low extracellular laccase activity was detected in the T. versicolor cultures but the addition of the laccase-mediator system did not lead to ketoprofen oxidation. The cytochrome P-450 inhibitor 1-aminobenzotriazole reduced ketoprofen oxidation. These data suggest that the first oxidation step is cytochrome P450 mediated. During time-course degradation experiments, three intermediates were structurally elucidated and quantified by HPLC-DAD-MS and NMR: 2-[3-(4-hydroxybenzoyl)phenyl]-propanoic acid, 2-[(3-hydroxy(phenyl)methyl)phenyl]-propanoic acid, and 2-(3-benzoyl-4-hydroxyphenyl)-propanoic acid. The latter was reported for the first time in biological systems. After 7 d of incubation, only small amounts of 2-[(3-hydroxy(phenyl)methyl)phenyl]-propanoic acid (0.08mg) remained in the liquid medium in comparison with the initial ketoprofen dose (1.0mg), suggesting possible mineralization of ketoprofen.

Purification and Properties of Lipases/Esterases from aBacillusStrain for Enantioselective Resolution of (S)-Ketoprofen

A Bacillus strain having a certain extent of asymmetric resolution for (S)-ketoprofen was studied for its culture and conversion condition. The distribution and properties of lipases/esterases from its bacterial cell and the change of asymmetric resolution ability were also investigated. After purification by hydrophobic interaction chromatography and gel filtration, the lipase/esterase terase activity of active fraction was 61.7 times higher than the crude enzyme and the purity of 23 kDa protein increased more than 400 times. Hydrolytic activity of lipase/esterase using ketoprofen chloroethyl ester and pNPA as substrate remained essentially constant in the reaction system during the purification procedure. The above result clearly indicated that the application of hydrophobic interaction chromatography-gel filtration was fast, useful and effective when compared to the difficulties in purification of low content crude enzyme prepared directly from bacterial cells. Experimental results also indicated that there are several lipases/esterases in the bacillus cell selective to the optically active ketoprofen and the conversion result was derived from the comprehensive function of all these enzymes. This is a new way to understand the bacterial asymmetric resolution with high conversion rate and low optical purity. The ESI-QUAD-TOF mass spectrum was used to analyze 23 kDa protein. Protein identities were revealed by searching sequence databases (MSDB) with peptide sequence tags. The result showed that 23 kDa protein is a novel protein.

Enhanced transdermal delivery of ketoprofen from bioadhesive gels

The aim of this study was to evaluate and compare the in vitro and in vivo transdermal potential of bioadhesive gels of ketoprofen by using gelling polymers like sodium carboxymethylcellulose, xanthan gum, poloxamer 407 and carbopol 934P as bioadhesive polymer with and without penetration enhancer (oleic acid). The effect of oleic acid as a penetration enhancer was examined when it was added to the bioadhesive formulations. Gels were evaluated for bioadhesive force and viscosity. To study the in vitro potential of these formulations, permeation studies were performed with Franz diffusion cell using excised rat abdominal skin. Carrageenan induced rat paw edema model was used to investigate their in vivo performance. The commercial formulation of ketoprofen was used as a reference formulation. The in vitro permeation studies indicate that ketoprofen bioadhesive gel of poloxamer 407 with penetration enhancer was superior to gels of sodium carboxymethylcellulose and xanthan gum with penetration enhancer (oleic acid). The permeation rate of ketoprofen from poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer was higher (rat abdominal skin flux = 0.421 +/- 0.032 mg/cm(2)/h) than the permeation rate of sodium carboxymethylcellulose and xanthan gum based bioadhesive gel with 15% v/w penetration enhancer. In the paw edema test poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer showed the best permeation and effectiveness. The in vitro and in vivo studies showed that bioadhesive gels of ketoprofen could be used for effective therapy.

Purification, crystallization and preliminary crystallographic analysis of Est25: a ketoprofen-specific hormone-sensitive lipase

Ketoprofen, a nonsteroidal anti-inflammatory drug, inhibits the synthesis of prostaglandin. A novel hydrolase (Est25) with high ketoprofen specificity has previously been identified using a metagenomic library from environmental samples. Recombinant Est25 protein with a histidine tag at the N-terminus was expressed in Escherichia coli and purified in a homogenous form. Est25 was crystallized from 2.4 M sodium malonate pH 7.0 and X-ray diffraction data were collected to 1.49 A using synchrotron radiation. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 197.8, b = 95.2, c = 99.4 A, beta = 97.1 degrees.

Identification and characterization of a novel (S)-ketoprofen-specific esterase

A new (S)-ketoprofen specific esterase (EST-Y29) was identified from a metagenome library from environmental samples, which showed homologies with class C-beta lactamase, penicillin binding protein, and other lipases/esterases. In order to investigate the biochemical and biophysical properties, the recombinant protein was overexpressed, purified to homogeneity, and characterized. This EST-Y29 has high catalytic activity against p-nitrophenyl esters of short fatty acids (C(2) and C(4)) and alpha-naphthyl acetate with activation energy of 30.4 kJ/mol. We have further characterized EST-Y29 using high performance liquid chromatography (HPLC), circular dichroism (CD), dynamic light scattering (DLS) and size exclusion chromatography (SEC).

Stereoselective Characteristics and Mechanisms of Epidermal Carboxylesterase Metabolism Observed in HaCaT Keratinocytes

There is increasing evidence that epidermal carboxylesterase may be involved in the stereoselective hydrolysis of prodrugs in percutaneous absorption. The present study was designed to evaluate the stereoselective characteristics and mechanisms of ketoprofen ethyl ester hydrolysis by epidermal carboxylesterase expressed in HaCaT keratinocytes. Ketoprofen ethyl ester was mainly hydrolyzed to R-ketoprofen by carboxylesterase of human HaCaT keratinocytes. Human carboxylesterase-1 (hCE-1) and human carboxylesterase-2 (hCE-2) were intensively detected in L02 hepatocytes, hCE-2 was also intensively detected in HaCaT keratinocytes, but hCE-1 was not detected in HaCaT keratinocytes. hCE-2 is thus an abundant carboxylesterase in HaCaT keratinocytes which may be responsible for stereoselective hydrolysis of ketoprofen ethyl ester.

Irreversible inhibition of glucose-6-phosphate dehydrogenase by the coenzyme A conjugate of ketoprofen: a key to oxidative stress induced by non-steroidal anti-inflammatory drugs?

Oxidative damage by non-steroidal anti-inflammatory drugs (NSAIDs) has been considered relevant to the occurrence of gastro-intestinal side-effects. In the case of chiral arylpropionate derivatives like ketoprofen (KPF), this mechanism has been evidenced for the R-enantiomer, especially when chiral inversion was observed, and lets us suppose the involvement of CoA conjugates. Glucose-6-phosphate dehydrogenase (G6PD) is the crucial enzyme to regenerate the GSH pool and maintain the intracellular redox potential. This enzyme is known to be down-regulated by palmitoyl-CoA thioester. We hypothesised then that G6PD is the target of carboxylic NSAIDs, via their CoA metabolites. We used molecular docking to localise a putative site in the human G6PD then we chose the Yeast orthologue, as the most suitable species to study experimentally the precise molecular interaction. KPF-CoA was effectively shown to bind covalently to the unique cysteine residue of the yeast enzyme. Binding was found to occur in the same site as palmitoyl-CoA. It was decreased in the presence of an allosteric inhibitor of G6PD, phospho(enol)pyruvate, and was not detected with G6PD of Leuconostoc mesenteroides, which does not possess the allosteric site. This site is distinct from the catalytic site, and probably allosteric, explaining the observed non-competitive inhibition of its activity by KPF-CoA. KPF-CoA was shown to induce the production of reactive oxygen species in Caco-2 cells, where its inhibition of G6PD activity was observed.

The delivery of ketoprofen from a system containing ion-exchange fibers

A postulated model for transdermal delivery using ion-exchange fibers as controlling device was designed, and the main objective of this study was to assess the rationality of the model. The release rates of ketoprofen from the carbopol-based gel vehicles containing ion-exchange fibers to which the ketoprofen had been bound have been determined across 0.22 microm microporous membrane. The fluctuation of the release rate of ketoprofen from the vehicles was much lower compared with that of simple gels, though the cumulative amount of ketoprofen delivery was less. Additional ions could increase the rate and extent of ketoprofen delivery. The iontophoretically assisted transport of ketoprofen across rat skin was also studied and found to be favorable to ketoprofen permeation. According to the tested model, the ion-layer could enhance the ketoprofen delivery and satisfactory results were achieved.

Evaluation of hydroxyimine as cytochrome P450-selective prodrug structure

Hydroxyimine derivatives of ketoprofen (1) and nabumetone (2) were synthesized and evaluated in vitro and in vivo as cytochrome P450-selective intermediate prodrug structures of ketones. 2 released nabumetone in vitro in the presence of isolated rat and human liver microsomes and in different recombinant human CYP isoforms. Bioconversion of 2 to both nabumetone and its active metabolite, 6-methoxy-2-naphthylacetic acid (6-MNA), was further confirmed in rats in vivo. Results indicate that hydroxyimine is a useful intermediate prodrug structure for ketone drugs.

Oxidation of Arg-410 promotes the elimination of human serum albumin

The effect of the oxidation of amino acid residues on albumin on its in vivo elimination was investigated using mutants and oxidized HSAs. The single-residue mutants (H146A, K199A, W214A, R218H, R410A, Y411A) and oxidized HSAs were produced by the recombinant DNA techniques and incubation with a metal ion-catalyzed oxidation (MCO) system for 12, 24, 48 or 72 h. Pharmacokinetics were evaluated in mice after labeling with 111In. Structural and functional properties were examined by several spectroscopic techniques. Time-dependent increase in carbonyl group content resulted in increase in the liver clearance of oxidized HSAs. Slight decreases in alpha-helical content as the result of oxidation was induced by the increases in accessible hydrophobic areas and the net negative charge on the HSA molecule. No significant change in the pharmacokinetics and structural properties was observed for the W214A, R218H and Y411A mutants, but the properties for the H146A, K199A and R410A mutants were affected (extent of effect: R410A > K199A > H146A). The liver clearance of these proteins is closely correlated to hydrophobicity (r = 0.929, P < 0.01) and the net charge of the proteins (r=0.930, P < 0.01). The rate of elimination of HSA is closely related to the hydrophobicity and net charge of the molecule. Further, the R410A mutants had a short half-life and structure similar to oxidized HSA after oxidation. Therefore, the modification of Arg-410 via oxidative stress may promote the elimination of HSA.

Film drying and complexation effects in the simultaneous skin permeation of ketoprofen and propylene glycol from simple gel formulations

This work investigated the simultaneous permeation of ketoprofen and propylene glycol (PG) across pig ear skin from simple gel formulations administered under simulated in-use conditions. The aims were to quantify rates of permeation of both solvent and active, probe the effects of formulation drying and gain insight into drag/complexation interactions. Simple 3-component gels were formulated using a fixed amount of ketoprofen and hydroxypropyl cellulose thickener with decreasing content of solvent propylene glycol. Multiple finite (5 mg x 15 mg) doses were massaged over 24h into full thickness pig ear skin in vertical Franz-type diffusion cells. The permeation of ketoprofen was inversely proportional to the content of PG, whereas the permeation of PG was directly proportional, although the amount of PG permeated was always greater than ketoprofen, even from the driest gel practically achievable. In this state, the molar ratio of PG/ketoprofen was approximately 12, suggesting that this number of PG molecules constitutes the solvation cage of ketoprofen. Dragging/pulling effect extends throughout the skin and into the receptor compartment and probably the system, in an in vivo situation. Although PG may represent a worse case scenario given its well-documented skin permeation enhancement properties, it is probable that other solvents exert a similar effect on solutes across skin. A drying film will behave in different ways depending on the nature of both the thickener and solvent, where the outcomes are not readily predictable. It is important to account for the fate of all species administered from a topical formulation.

Development and evaluation of an in vitro method for prediction of human drug absorption II. Demonstration of the method suitability

The aim of the present work was to assess the actual suitability and general applicability of a new in vitro permeation method based on an appositely developed artificial membrane to evaluate and predict drug absorption potential. The proposed method was employed to evaluate the apparent permeability of a set of 21 structurally diverse drugs having very different solubility and permeability properties, covering the whole range of fraction absorbed in humans (F(a) from 13 to 100%); 13 of the drugs in this study were part of the list suggested by FDA for validation of in vitro permeation methods. An excellent linear correlation (R(2)=0.957) was obtained between artificial membrane apparent permeability and human absorption data in the whole range of F(a) values examined (including all the drugs belonging to the above FDA list), indicating the good predictive ability of the proposed method not only for highly absorbed hydrophobic compounds but also, differently from other in vitro permeation methods, for poorly or middling permeable drugs. The predictive ability of the new method was greater than those obtained for the same set of drugs with PAMPA and Caco-2 permeability literature data, probably due to the poor sensitivity of these methods towards hydrophilic drugs. The better performance of our artificial membrane was attributed to the hydrophilic nature of the support that, differently from the commonly used hydrophobic supports, offers less resistance to permeation of hydrophilic compounds. A comparison of permeation data of theophylline, ketoprofen, aciclovir and furosemide (selected, respectively, as models of I-IV BCS classes) obtained using a Caco-2 cell based dynamic method and the developed artificial membrane and the corresponding F(a) values in humans further confirmed the suitability of the proposed permeation method as predictor of the oral absorption of passively absorbed drugs.

Influence of low-frequency massage device on transdermal absorption of ionic materials

The influence of a low-frequency massage device on transdermal absorption of sodium benzoate, ketoprofen and diclofenac sodium was investigated in rats. Electrode pads spread with a hydroxypropyl cellulose gel containing the drug model were placed on excised skin in vitro. The transdermal permeation studies were carried out in the treatment group with the pulse applied through electrode pads spread with the gel, the pretreatment group with the gel applied after the application of the pulse and in the control group in which the gel was applied without the pulse. In vivo, transdermal absorption of ketoprofen was examined in the same groups used for the in vitro study. The pharmacokinetics of ketoprofen in plasma after intravenous injection was also studied. The treatment group showed higher cumulative permeated amounts of the drug models than the control in vitro. However, the enhancing effect was not observed in the pretreatment group. In vivo, the plasma ketoprofen level increased temporarily after the pulse was applied and then increased gradually as compared with the control. Since the distribution of ketoprofen from the central to the peripheral compartment was enhanced by the pulse in the injection study, enhancement of the biodistribution of ketoprofen by the low-frequency pulse was suggested.

Pathways and metabolites of microbial degradation of selected acidic pharmaceutical and their occurrence in municipal wastewater treated by a membrane bioreactor

Laboratory degradation tests with five acidic pharmaceuticals using activated sludge as inocculum under aerobic conditions were performed and microbial metabolites were analysed by liquid chromatography-mass spectrometry (LC-MS). Ketoprofen was partly mineralized as a sole source of carbon and energy and the metabolites determined by LC-MS suggest microbial ketoprofen degradation to proceed along the pathway known for biphenyls and related compounds. Bezafibrate, naproxen and ibuprofen were degraded only cometabolically whereas no transformation was obtained for diclofenac. Some biodegradation intermediates in these batch tests could be tentatively identified by means of LC-MS. The first step in microbial bezafibrate degradation appears to be the hydrolytic cleavage of the amide bond, generating well degradable 4-chlorobenzoic acid as one of the hydrolysis products. As previously found for mammals, ether cleavage and formation of desmethylnaproxen was the initial step in microbial degradation of naproxen. Two isomers of hydroxy-ibuprofen were detected as intermediates in the mineralization of ibuprofen. Laboratory studies suggest that naproxen and ibuprofen can be fully mineralized whereas more stable metabolites occur in microbial ketoprofen and bezafibrate transformation, that may deserve further attention. A LC-MS method for the trace analysis of these metabolites in water was developed and applied to municipal wastewater. Municipal wastewater treatment by a membrane bioreactor may gradually improve the removal of these pharmaceuticals.

Regioselective Enzymatic Synthesis of Non-Steroidal Anti-Inflammatory Drugs Containing Glucose in Organic Media

Enzymatic transesterification of glucose with the vinyl ester of non-steroidal anti-inflammatory drugs (NSAIDs) was in organic media performed for synthesis of novel NSAIDs-glucose conjugates. Glucose was regioselectively acylated at the 6-hydroxyl group. The indomethacin-glucose conjugate and ketoprofen-glucose conjugate were produced by the catalysis of alkaline protease from Bacillus subtilis in the respective yields of 42% (over 48 h) and 63% (over 40 h). The etodolac-glucose conjugate was obtained in 26% yield (over 144 h) by lipase from Candida antarctica.

FUNCTIONAL INVOLVEMENT OF RAT ORGANIC ANION TRANSPORTER 2 (SLC22A7) IN THE HEPATIC UPTAKE OF THE NONSTEROIDAL ANTI-INFLAMMATORY DRUG KETOPROFEN

Rat organic anion transporter 2 (rOat2, Slc22a7) is a sinusoidal multispecific organic anion transporter in the liver. The role of rOat2 in the hepatic uptake of drugs has not been thoroughly investigated yet. rOat2 substrates include nonsteroidal anti-inflammatory drugs, such as ketoprofen, indomethacin, and salicylate. In the present study, the uptake of ketoprofen, indomethacin, and salicylate by freshly isolated rat hepatocytes was characterized. The uptake of ketoprofen, indomethacin, and salicylate by hepatocytes was sodium-independent, and the rank order of their uptake activities was indomethacin > ketoprofen > salicylate. Kinetic analysis based on Akaike's Information Criterion suggested that the uptake of ketoprofen and indomethacin by hepatocytes consists of two saturable components and one nonsaturable one. The K(m) and V(max) values for the high- and low-affinity components for ketoprofen uptake were 0.84 and 97 microM and 35 and 1800 pmol/min/mg protein, respectively, whereas those for indomethacin were 1.1 and 140 microM and 130 and 16,000 pmol/min/mg protein, respectively. The K(m) values of the high-affinity component were similar to those for rOat2 (3.3 and 0.37 microM for ketoprofen and indomethacin, respectively). The uptake of ketoprofen by hepatocytes was significantly inhibited by probenecid and rOat2 inhibitors (indocyanine green, indomethacin, glibenclamide, and salicylate). Other inhibitors of rOatps (taurocholate and pravastatin) and rOat3 (pravastatin and p-aminohippurate) had a slight effect, but digoxin had no effect. These results suggest that rOat2 accounts partly for the hepatic uptake of ketoprofen and, presumably, indomethacin as a high-affinity site and that other transporters, such as rOatps, but not rOatp2, and rOat3, are also involved.

[Stereoselectivity of skin carboxylesterase metabolism]

AIM

To study the stereoselectivity of skin carboxylesterase metabolism and its molecular biological foundation for improving drug percutaneous absorption.

METHODS

Ketoprofen ethyl ester was used as a model drug, and skin homogenate was applied for studying the stereoselectivity of carboxylesterase metabolism. Human liver L02 cell was used as control of carboxylesterase expression, and RT-PCR was used for studying the expression of carboxylesterase.

RESULTS

The main metabolite of ketoprofen ethyl ester in human skin homogenate was R-ketoprofen. Human carboxylesterase-2 was highly expressed in skin and its cells. However, the expression of human carboxylesterase-1 was very weak or not detectable.

CONCLUSION

Human carboxylesterase-2 is the main hydrolytic enzyme of prodrugs in percutaneous absorption, and shows metabolic stereoselectivity to prodrugs with chiral esters.

Kinetic resolution of ketoprofen ester catalyzed by lipase from a mutant of CBS 5791

A biotransformation process was developed for the production of (S)-ketoprofen by enantioselective hydrolysis of racemic ketoprofen ester using the mutant Trichosporon laibacchii strain CBS 5791. A satisfactory result was obtained, in which the E was 82.5, with an ee of 0.94 and a conversion of 0.47 under the optimum hydrolysis conditions [E is enantiomeric ratio, E=ln[1-X(1+ee)]/ln[1-X(1-ee)]; ee is enantiomeric excess, ee=(CS-CR)/(CS+CR): temperature of hydrolysis was 23 degrees C]. The medium used in biotransformation was a mixture of growth broth and biotransformation broth at a ratio of 1:9, the concentration of Tween 80 was 15 g/l, the time of hydrolysis, 72 h. These results are promising for further scale-up. Tween 80 significantly improved lipase enantioselectivity and activity at the optimum concentration.

Simultaneous HPLC determination of ketoprofen and its degradation products in the presence of preservatives in pharmaceuticals

A novel and quick high-performance liquid chromatography (HPLC) method with UV spectrophotometric detection was developed and validated for the determination of five compounds in topical gel. The described method is suitable for simultaneous determination of active component ketoprofen, two preservatives methylparaben and propylparaben and two degradation products of ketoprofen--3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid--in a topical cream after long-term stability tests using ethylparaben as an internal standard. The chromatographic separation was performed on a 5microm Supelco Discovery C18 column (125mm x 4mm i.d., Sigma-Aldrich); the optimal mobile phase for separation of ketoprofen, methylparaben, propylparaben, degradation products 3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid and ethylparaben as internal standard consists of a mixture of acetonitril, water and phosphate buffer pH 3.5 (40:58:2, v/v/v). At a flow rate of 1.0ml min(-1) and detection at 233nm, the total time of analysis was less than 10min. The method was applied for routine analysis (batch analysis and stability tests) of these compounds in topical pharmaceutical product.

Carboxyl nonsteroidal anti-inflammatory drugs are efficiently glucuronidated by microsomes of the human gastrointestinal tract

Limited studies have been carried out on the biotransformation of carboxyl nonsteroidal anti-inflammatory drugs (NSAIDs) in the liver. However, the role of the intestine in NSAID metabolism has not been investigated. In this report, the contribution of UDP-glucuronosyltransferases (UGTs) in the human gastrointestinal (GI) tract from five donors to the glucuronidation of the NSAIDs, RS-ketoprofen, S-naproxen, RS- and S-etodolac, was investigated. UGT activity and, for some donors, mRNA levels were evaluated. All NSAIDs were glucuronidated throughout the GI tract; however, glucuronidation was low in stomach and duodenum as compared to the remainder of the intestine. RT-PCR analysis demonstrated that the UGT1A isoforms, UGT1A3, 1A8, and 1A10, and UGT2B7 were expressed in the GI tract. Human recombinant UGT1A3, 1A9, 1A10 and 2B7 were actively involved in the glucuronidation of all NSAIDs while UGT1A7 and the intestine-specific UGT1A8 had no glucuronidating activity towards those compounds. Despite interindividual variations in both the levels of mRNA and the distribution of activity through the intestine, UGTs in the GI tract may contribute significantly to the first pass metabolism of orally administered NSAIDs.

Integration of purification with immobilization of Candida rugosa lipase for kinetic resolution of racemic ketoprofen

The two processes for the partial purification and for the immobilization of a crude lipase preparation (Candida rugosa Lipase OF) have been successfully integrated into one by simple adsorption of the enzyme onto a cation ion exchanger resin (SP-Sephadex C-50) at pH 3.5. Due to selective removal of the unfavorable lipase isoenzyme (L1), the enzyme components (mainly L2 and L3) that are tightly fixed on the resin displayed a significantly improved enantioselectivity (E value: 50 versus 13 with addition of Tween-80) in the biocatalytic hydrolysis of 2-chloroethyl ester of rac-ketoprofen. The activity yields of the immobilized lipase were 48 and 70%, respectively when emulsified and non-emulsified substrates were employed for enzyme assay. Moreover, the concentration of Tween-80 was found to be a factor affecting the lipase enantioselectivity. By using such an immobilized enzyme as biocatalyst, the process for preparing enantiopure (S)-ketoprofen becomes simpler and more practical as compared with the previously reported procedures and the product was obtained with >94% ee at 22.3% conversion in the presence of an optimal concentration (0.5 mg/ml) of Tween-80 at pH 3.5. Furthermore, the operational stability of the immobilized biocatalyst was examined in different types of reactors. In an air-bubbled column reactor, the productivity was much higher than that in a packed-bed column reactor, in spite of a slightly lower stability. Under optimal conditions, the air-bubbled column reactor could be operated smoothly for at least 350 h, remaining nearly 50% activity.

[Establishment and application of in situ perfused pig ear model for percutaneous absorption]

AIM

To establish an in situ perfused pig ear model for percutaneous absorption.

METHODS

The in situ perfused pig ear model for percutaneous absorption consisted of artificial gas, sample chamber, constant flow pump, constant temperature system, polytetrafluorethylene connective tube, porcine ear vein, porcine ear skin and special laminar flow apparatus. The perfused system viability was assessed by glucose utilization and lactate production. Ketoprofen isopropyl ester and methyl salicylate was used for validating this model. The concentrations of perfused sample were measured by HPLC.

RESULTS

Glucose utilization and lactate production showed that this model was viable till 7 h. Ketoprofen isopropyl ester was completely metabolized to ketoprofen in situ in perfused pig ear model. The steady cumulative amount (Q) of ketoprofen from permeation and metabolism was linear with time (t), the equation of ketoprofen formation was Q = -0.024 + 0.120t, the rate of ketoprofen formation was 0.120 microgram.cm-2.h-1. Methyl salicylate was partially metabolized to salicylic acid. The steady cumulative amount (Q) of methyl salicylate from permeation was linear with time (t), the permeation equation of methyl salicylate was Q = -3.809 + 6.129t, the permeation rate of metyl salicylate was 6.129 micrograms.cm-2.h-1. The steady cumulative amount (Q) of salicylic acid from metabolism was also linear with time (t), the formation equation of salicylic acid was Q = -1.785 + 0.879t, the formation rate of salicylic acid was 0.879 microgram.cm-2.h-1.

CONCLUSION

The in situ pig ear vein perfused model is a novel easy-handing and cost-efficient technique for percutaneous absorption and skin metabolism.

Improved production of ( S)-ketoprofen ester hydrolase by a mutant of Trichosporon brassicae CGMCC 0574

An efficient screening method following UV mutagenesis yielded a high frequency of improved mutants of Trichosporon brassicae CGMCC 0574, a wild-type esterase-producer capable of enantioselectively hydrolyzing the ethyl ester of ketoprofen [2-(3-benzoylphenyl) propionic acid]. The mutant had an activity 1.8-fold higher than the wild type and was stable in its enzyme production for ten serial transfers. As the best single carbon source, isopropanol improved the specific activity of the enzyme 5-fold; and this did not result from the effect of cell permeabilization. An 18-h culture grown on a medium containing 0.5% glucose plus 0.5% isopropanol produced 3-fold as much esterase as a culture grown on 1% glucose.

Synthesis of acylglucuronides of drugs using immobilized dog liver microsomes octadecylsilica particles coated with phospholipid

Immobilized dog liver microsome octadecylsilica (ODS) particles coated with phospholipid were developed for the synthesis of acylglucuronides of drugs. The phospholipid-coated ODS particles were readily prepared by stirring a solution containing L-alpha-dipalmitoylphosphatidylcholine with the ODS particles, in which the phospholipid was absorbed on the ODS surfaces by hydrophobic interaction between the acyl group of phospholipid and the otcadecyl group of the ODS particles. Similarly, the microsome-immobilized particles were readily prepared by stirring a buffer solution containing dog liver microsomes with the phospholipid-coated ODS particles, in which the microsomes were immobilized on the phospholipid-coated ODS particles by hydrophobic binding. The microsome-immobilized particles exhibited UDP-glucuronosyltransferase activity which catalyzed the glucuronidation of ketoprofen and a nonpeptide endothelin receptor antagonist, S-1255 ([R]-[+]-2-[benzo(1,3)dioxol-5-yl]-6-isopropyl-4-[4-methoxyphenyl]-2H-chromene-3-carboxylic acid), to the corresponding acylglucuronide in the presence of uridine 5(')-diphosphate (UDP)-glucuronic acid, and two acylglucuronides of ketoprofen and S-1255 were synthesized using the microsome-immobilized particles. These acylglucuronides were synthesized by simply shaking the microsome-immobilized particles adsorbed on the substrate in a buffer solution containing UDP-glucuronic acid with a thermostated mixer. The molecular weights and chemical structures of the synthesized acylglucuronides were identified by mass spectrometry and nuclear magnetic resonance, respectively. The productivity of S-1255 acylglucuronide using microsome-immobilized particles was approximately threefold higher than that observed with free microsomes, whereas the ketoprofen acylglucuronide productivity was slightly lower than that observed with free microsomes. The present method should be very useful for the synthesis of acylglucuronides of drugs, which are slightly soluble aqueous solutions in the drug development stage.

A systematic approach for yielding a potential pool of enzymes: practical case for chiral resolution of (R,S)-ketoprofen ethyl ester

A systematic approach for the selection of potential biocatalysts from a natural source was developed and then a practical application was addressed. The approach that involves systematically combined conventional screening methods and current tools comprises the following consecutive steps: strain enrichment for activity screening, identification of positive strains, choosing whole genome-sequenced strains as candidates, gathering information about responsible enzymes, bioinformatic analyses and gene mining, probing genetic molecules and then functional expression. The target compound (R,S)-ketoprofen ethyl ester was to be resolved into an enantiomer, and a potential esterase from Pseudomonas fluorescens KCTC 1767 was prepared by the proposed procedure. The enzyme had a high activity and also strict selectivity for the enantiomer (S)-ketoprofen and was suitable therefore as a biocatalyst for practical use. The result achieved by the combined approach could not easily be obtained using other approaches with typical procedures. Hence the approach proposed here should be of considerable use for the screening of potential enzymes, particularly for enzymes with desired activity to unnatural substrates, from conditionally expressed and/or repressed proteins that are distributed widely in natural pools under normal conditions.

Study on the protein binding of ketoprofen using capillary electrophoresis frontal analysis compared with liquid chromatography frontal analysis

A method of capillary electrophoresis frontal analysis (CEFA) is developed for the first time to study the binding of ketoprofen to human serum albumin (HSA) and compared with high-performance liquid chromatography frontal analysis (LCFA). The separation is performed in an uncoated fused-silica capillary (60-cm x 75- micro m i.d., 50-cm effective length) with a phosphate buffer (pH 7.4, ionic strength of 0.17M) as the running buffer. The applied voltage is 13 kV and the detection is set at 254 nm. A trapezoidal peak of the unbound ketoprofen appears after HSA elution in the electropherogram. The plateau height of the peak is employed to determine the unbound concentration of ketoprofen in the HSA equilibrated sample solution. The CEFA method provides the advantages of small sample injection volume and rapidity and the disadvantage of low sensitivity compared with LCFA. CEFA is applicable to the binding parameter estimation of ketoprofen to the secondary binding site; an association constant (K(2)) of 0.24 x 10(6)M(-1) and the number for the binding site per molecule HSA of 2.54 is estimated. In contrast, LCFA measures parameters for both primary and secondary sites, which are 1.05 x 10(6)M(-1) and 0.94 for K(1) and n(1), respectively, and 0.12 x 10(6)M(-1) and 3.16 for K(2) and n(2), respectively. It is found that ketoprofen binds mainly at the primary site at a molecular ratio of ketoprofen versus HSA lower than 0.75, and the binding at the secondary site occurs at a higher ratio.

Stereospecific pH-dependent degradation kinetics of R- and S-naproxen-beta-l-O-acyl-glucuronide

The hydrolysis and acyl migration of biosynthetic S-naproxen-beta-l-O-acyl glucuronide (I) and R-naproxen-beta-l-O-acyl glucuronide (II) was followed by HPLC. Nine first-order kinetic rate constants for the hydrolysis and acyl migration between the beta-l-O-acyl glucuronide, its alpha/beta-2, alpha/beta-3-, alpha/beta-4-, and alpha-1-O-acyl isomers and naproxen aglycone were determined for I and II at pH 7.00, 7.40 and 8.00 at 37 degrees C by kinetic simulation. For I the 3-O-acyl isomer was the most stable isomer as the pseudo-equilibrium ratio for the major acyl-migrated isomers was 1:1.5:0.9 (2-O-acyl isomer:3-O-acyl isomer:4-O-acyl isomer). The 3- and 4-O-acyl isomers of II were equally stable as the pseudo-equilibrium ratio for the major acyl-migrated isomers was 1:1.4:1.4 (2-O-acyl isomer:3-O-acyl isomer:4-O-acyl isomer). For both I and II, the pseudo-equilibrium ratio between the major 2-O-acyl isomer and the minor alpha-l-O-acyl isomer was 10:1 (2-O-acyl isomer:alpha-l-O-acyl isomer). The pseudo-equilibrium found for the major acyl-migrated isomers of I and II in the present study corresponds with the pattern previously published for R- and S-ketoprofen-beta-l-O-acyl glucuronide acyl-migrated isomers, suggesting that these findings may be general for acyl-migrated beta-l-O-acyl glucuronides of enantiomeric 2-arylpropionic acids.